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Abdu MA, Brum CG, Batista PP, Gurubaran S, Pancheva D, Bageston JV, Batista IS and Takahashi H (2015), "Fast and ultrafast Kelvin wave modulations of the equatorial evening F region vertical drift and spread F development", Earth, Planets and Space., Jan, 2015. Vol. 67(1)
Abstract: In this paper, we investigate the role of eastward and upward propagating fast (FK) and ultrafast Kelvin (UFK) waves in the day-to-day variability of equatorial evening prereversal vertical drift and post sunset generation of spread F/plasma bubble irregularities. Meteor wind data from Cariri and Cachoeira Paulista (Brazil) and medium frequency (MF) radar wind data from Tirunelveli (India) are analyzed together with Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) temperature in the 40- to 100-km region to characterize the zonal and vertical propagations of these waves. Also analyzed are the F region evening vertical drift and spread F (ESF) development features as diagnosed by Digisonde (Lowell Digisonde International, LLC, Lowell, MA, USA) operated at Fortaleza and Sao Luis in Brazil. The SABER temperature data permitted determination of the upward propagation characteristics of the FK (E1) waves with propagation speed in the range of 4 km/day. The radar mesosphere and lower thermosphere (MLT) winds in the widely separated longitude sectors have yielded the eastward phase velocity of both the FK and UFK waves. The vertical propagation of these waves cause strong oscillation in the F region evening prereversal vertical drift, observed for the first time at both FK and UFK periodicities. A delay of a few (approximately 10) days is observed in the F region vertical drift perturbation with respect to the corresponding FK/UFK zonal wind oscillations, or temperature oscillations in the MLT region, which has permitted a direct identification of the sunset electrodynamic coupling process as being responsible for the generation of the FK/UFK-induced vertical drift oscillation. The vertical drift oscillations are found to cause significant modulation in the spread F/plasma bubble irregularity development. The overall results highlight the role of FK/UFK waves in the day-to-day variability of the ESF in its occurrence season.
BibTeX:
@article{Abdu2015,
  author = {Abdu, Mangalathayil A and Brum, Christiano GM and Batista, Paulo P and Gurubaran, Subramanian and Pancheva, Dora and Bageston, Jose V and Batista, Inez S and Takahashi, Hisao},
  title = {Fast and ultrafast Kelvin wave modulations of the equatorial evening F region vertical drift and spread F development},
  journal = {Earth, Planets and Space},
  year = {2015},
  volume = {67},
  number = {1},
  url = {http://dx.doi.org/10.1186/s40623-014-0143-5},
  doi = {10.1186/s40623-014-0143-5}
}
Park J, Stolle C, Xiong C, LÝhr H, Pfaff RF, Buchert S and Martinis CR (2015), "A dayside plasma depletion observed at midlatitudes during quiet geomagnetic conditions", Geophysical Research Letters. Vol. 42(4), pp. 967-974.
Abstract: In this study we investigate a dayside, midlatitude plasma depletion (DMLPD) encountered on 22 May 2014 by the Swarm and GRACE satellites, as well as ground-based instruments. The DMLPD was observed near Puerto Rico by Swarm near 10 LT under quiet geomagnetic conditions at altitudes of 475–520?km and magnetic latitudes of ?25°–30°. The DMLPD was also revealed in total electron content observations by the Saint Croix station and by the GRACE satellites (430?km) near 16?LT and near the same geographic location. The unique Swarm constellation enables the horizontal tilt of the DMLPD to be measured (35° clockwise from the geomagnetic east-west direction). Ground-based airglow images at Arecibo showed no evidence for plasma density depletions during the night prior to this dayside event. The C/NOFS equatorial satellite showed evidence for very modest plasma density depletions that had rotated into the morningside from nightside. However, the equatorial depletions do not appear related to the DMLPD, for which the magnetic apex height is about 2500?km. The origins of the DMLPD are unknown, but may be related to gravity waves.
BibTeX:
@article{GRL:GRL52558,
  author = {Park, Jaeheung and Stolle, Claudia and Xiong, Chao and LÝhr, Hermann and Pfaff, Robert F. and Buchert, Stephan and Martinis, Carlos R.},
  title = {A dayside plasma depletion observed at midlatitudes during quiet geomagnetic conditions},
  journal = {Geophysical Research Letters},
  year = {2015},
  volume = {42},
  number = {4},
  pages = {967--974},
  url = {http://dx.doi.org/10.1002/2014GL062655},
  doi = {10.1002/2014GL062655}
}
Sarkhel S, Mathews J, Raizada S, Sekar R, Chakrabarty D, Guharay A, Jee G, Kim J-H, Kerr R, Ramkumar G, Sridharan S, Wu Q, Mlynczak M and Russell JamesM I (2015), "A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India", Earth, Planets and Space. Vol. 67(1) Springer Berlin Heidelberg.
Abstract: The height-time-concentration map of neutral sodium (Na) atoms measured by a Na lidar during the night of 18 to 19 March 2007 over Gadanki, India (13.5° N, 79.2° E) reveals an unusual structure in the Na layer for around 30 min in the altitude range of 92 to 98 km which is similar to the usual ‘C’ type structures observed at other locations. In order to understand the physical mechanism behind the generation of this unusual event, an investigation is carried out combining the data from multiple instruments that include the meteor wind radar over Thiruvananthapuram, India (8.5° N, 77° E) and the SABER instrument onboard the TIMED satellite. The temperature and wind profiles from the data set provided by these instruments allow us to infer the Richardson number which is found to be noticeably less than the canonical threshold of 0.25 above 92 km over Thiruvananthapuram suggesting the plausible generation of Kelvin-Helmholtz (KH) billows over southwestern part of the Indian subcontinent. Based on the average wind speed and direction over Thiruvananthapuram, it is proposed that the KH-billow structure was modified due to the background wind and was advected with it in nearly ‘frozen-in’ condition (without significant decay) in the northeastward direction reaching the Na lidar location (Gadanki). This case study, therefore, presents a scenario wherein the initially deformed KH-billow structure survived for a few hours (instead of a few minutes or tens of minutes as reported in earlier works) in an apparently ‘frozen-in’ condition under favorable background conditions. In this communication, we suggest a hypothesis where this deformed KH-billow structure plays crucial role in creating the abovementioned unusual structure observed in the Na layer over Gadanki.
BibTeX:
@article{raey,
  author = {Sarkhel, Sumanta and Mathews, JohnD and Raizada, Shikha and Sekar, Ramanathan and Chakrabarty, Dibyendu and Guharay, Amitava and Jee, Geonhwa and Kim, Jeong-Han and Kerr, RobertB and Ramkumar, Geetha and Sridharan, Sundararajan and Wu, Qian and Mlynczak, MartinG and Russell, JamesM, III},
  title = {A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India},
  journal = {Earth, Planets and Space},
  publisher = {Springer Berlin Heidelberg},
  year = {2015},
  volume = {67},
  number = {1},
  url = {http://dx.doi.org/10.1186/s40623-015-0183-5},
  doi = {10.1186/s40623-015-0183-5}
}
Xiong C, LÝhr H, Ma S and Schlegel K (2015), "Validation of GRACE electron densities by incoherent scatter radar data and estimation of plasma scale height in the topside ionosphere", Advances in Space Research., August, 2015. Vol. 119(0), pp. 2048-2057.
Abstract: Abstract This paper presents an effort of using incoherent scatter radar data for validating electron density (Ne) measurements performed by the GRACE satellites from year 2002 to 2012. For adjusting the bias of GRACE Ne data, the observations at high latitudes from EISCAT at TromsÜ and Svalbard, as well as two incoherent scatter radars (ISR) at mid- and low latitudes, Millstone Hill and Arecibo, are used. The adjusted GRACE Ne data are further compared with the observations from the four ISRs. For EISCAT observations at TromsÜ and Svalbard the comparison results are quite consistent, yielding correlation coefficients as high as 0.92, and an average bias value of about 3e10 m?3 is obtained. For the radars at Millstone Hill and Arecibo the results show excellent agreement, yielding correlation coefficients as high as 0.97 and an average bias of 1e10 m?3. The scale factor of adjusted GRACE Ne data is lower by 1% and 5% compared to Millstone Hill and Arecibo readings, respectively. We consider these differences as within the uncertainty of radar measurements. Using the adjusted GRACE Ne as well as CHAMP observations during four periods of coplanar orbits between 2003 and 2008, the plasma scale heights of the topside ionosphere are determined and further compared with IRI model predictions. We find significantly larger scale heights in particular at middle and high latitudes than expected from IRI. Outstanding are the regions of the mid-latitude electron density trough.
BibTeX:
@article{Xiong2014,
  author = {Chao Xiong and Hermann LÝhr and ShuYing Ma and Kristian Schlegel},
  title = {Validation of GRACE electron densities by incoherent scatter radar data and estimation of plasma scale height in the topside ionosphere},
  journal = {Advances in Space Research},
  year = {2015},
  volume = {119},
  number = {0},
  pages = {2048-2057},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117714004785},
  doi = {10.1016/j.asr.2014.07.022}
}
BÆsinger T, Demekhov AG, Ermakova EN, Haldoupis C and Zhou Q (2014), "Pulsating nighttime magnetic background noise in the upper ULF band at low latitudes", Journal of Geophysical Research: Space Physics., May, 2014. Vol. 119(5), pp. 4109-4119.
Abstract: We model long-period (~2?h) irregular pulsations in the ellipticity of magnetic background noise (MBN) in the upper ULF band which were frequently observed during nighttime at a low-latitude site on the Island of Crete. It is shown that such pulsations cannot be reproduced in the calculations when using the ionosphere parameters from the statistical IRI (International Reference Ionosphere) model, while regular diurnal signatures of the ellipticity spectrum at sunset and sunrise are successfully reproduced. We apply the same approach to the location of the Arecibo incoherent scatter radar and show that using actually measured ionosphere profiles (up to a height of 400?km) instead of IRI profiles produces the ellipticity pulsations very similar to those observed at Crete. Comparison of model results with the calculated behavior of AlfvÈn mode refractive index allows us to conclude that the observed nighttime long-period irregular pulsations in the MBN ellipticity are caused by dynamic processes at the upper boundary of the ionospheric E-F valley which serves as a subionospheric AlfvÈn resonator. Irregular widening, shrinking, and/or deepening of the valley with time scales of 1 to 4?h affect the electrodynamical properties of this resonator and manifest themselves in the magnetic background noise properties.
BibTeX:
@article{Boesinger2014,
  author = {BÆsinger, T. and Demekhov, A. G. and Ermakova, E. N. and Haldoupis, C. and Zhou, Q.},
  title = {Pulsating nighttime magnetic background noise in the upper ULF band at low latitudes},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {5},
  pages = {4109--4119},
  url = {http://dx.doi.org/10.1002/2014JA019906},
  doi = {10.1002/2014JA019906}
}
Dawkins ECM, Plane JMC, Chipperfield MP, Feng W, Gumbel J, Hedin J, HÆffner J and Friedman JS (2014), "First global observations of the mesospheric potassium layer", Geophysical Research Letters., August, 2014. Vol. 41(15), pp. 5653-5661.
Abstract: Metal species, produced by meteoric ablation, act as useful tracers of upper atmosphere dynamics and chemistry. Of these meteoric metals, K is an enigma: at extratropical latitudes, limited available lidar data show that the K layer displays a semiannual seasonal variability, rather than the annual pattern seen in other metals such as Na and Fe. Here we present the first near-global K retrieval, where K atom number density profiles are derived from dayglow measurements made by the Optical Spectrograph and Infrared Imager System spectrometer on board the Odin satellite. This robust retrieval produces density profiles with typical layer peak errors of ±15% and a 2?km vertical grid resolution. We demonstrate that these retrieved profiles compare well with available lidar data and show for the first time that the unusual semiannual behavior is near-global in extent. This new data set has wider applications for improving understanding of the K chemistry and of related upper atmosphere processes.
BibTeX:
@article{Dawkins2014a,
  author = {Dawkins, E. C. M. and Plane, J. M. C. and Chipperfield, M. P. and Feng, W. and Gumbel, J. and Hedin, J. and HÆffner, J. and Friedman, J. S.},
  title = {First global observations of the mesospheric potassium layer},
  journal = {Geophysical Research Letters},
  year = {2014},
  volume = {41},
  number = {15},
  pages = {5653--5661},
  url = {http://dx.doi.org/10.1002/2014GL060801},
  doi = {10.1002/2014GL060801}
}
Deng Y, Huang Y, Wu Q, Noto J, Drob D and Kerr RB (2014), "Comparison of the neutral wind seasonal variation from midlatitude conjugate observations", Journal of Geophysical Research: Space Physics., April, 2014. Vol. 119(4), pp. 3029-3035.
Abstract: The seasonal variation of F region neutral wind from the midlatitude conjugate Fabry-Perot interferometer observations has been studied. The meridional wind at Palmer station (64°S,64°W) has a significant local time dependence with strong equatorward wind at midnight and polarward wind at dawn and dusk. The zonal wind switches from eastward to westward in the early morning section. From the June solstice (austral winter) to equinox, the maximum meridional wind increases from 90?m/s to 130?m/s, and the zonal wind switches direction at an earlier local time. The neutral winds from Palmer have been compared with those from the geomagnetic conjugate location, Millstone Hill (MH). At equinox, the local time variation of neutral wind shows a very good conjugacy between these two locations. But at June solstice, the similarity in the zonal wind becomes less clear. This seasonal dependence can be attributed to the seasonal variation of solar and geomagnetic forcings. The annual variation of daily average neutral wind from Palmer and MH has also been compared. The meridional wind shows a clear offset of season, and the magnitude at Palmer is averagely 40?m/s more equatorward than that at MH. The zonal wind is dominantly westward at Palmer and eastward at MH. The annual variation of neutral wind, especially the zonal component, is much less symmetric between the two sites than the local time variation. The empirical horizontal wind model shows a good agreement with the observations in both local time and annual variations.
BibTeX:
@article{Deng2014,
  author = {Deng, Yue and Huang, Yanshi and Wu, Qian and Noto, John and Drob, Douglas and Kerr, Robert B.},
  title = {Comparison of the neutral wind seasonal variation from midlatitude conjugate observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {4},
  pages = {3029--3035},
  url = {http://dx.doi.org/10.1002/2013JA019716},
  doi = {10.1002/2013JA019716}
}
Hysell DL, Larsen MF and Sulzer MP (2014), "High time- and height-resolution neutral wind profile measurements across the mesosphere/lower thermosphere region using the Arecibo incoherent scatter radar", Journal of Geophysical Research: Space Physics., March, 2014. Vol. 119, pp. 2345-2358.
Abstract: A method for estimating the vector neutral wind profiles in the mesosphere and lower thermosphere (MLT) region of the upper atmosphere from Arecibo dual-beam incoherent scatter radar data is presented. The method yields continuous estimates of both the altitude-averaged F-region plasma drifts and all three components of the altitude-resolved neutral wind profiles in the MLT using data taken while the Arecibo feed system swings in azimuth. The problem is mixed determined, and its solution is not inherently unique. Second order Tikhonov regularization is used to find solutions consistent with the available data while being minimally structured, additional structure being unsupported by the data. The solution is found using the method of conjugate gradient least squares and sparse matrix mathematics. Example data acquired during an interval of midlatitude spread F are used to illustrate the method. The estimated wind profiles exhibit characteristics broadly consistent with gravity waves but are impulsive, with features that generally persist for less than one and a half wave periods.
BibTeX:
@article{Hysell2014,
  author = {Hysell, D. L. and Larsen, M. F. and Sulzer, M. P.},
  title = {High time- and height-resolution neutral wind profile measurements across the mesosphere/lower thermosphere region using the Arecibo incoherent scatter radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  pages = {2345-2358},
  url = {http://dx.doi.org/10.1002/2013JA019621},
  doi = {10.1002/2013JA019621}
}
Hickey DA, Martinis CR, Erickson PJ, Goncharenko LP, Meriwether JW, Mesquita R, Oliver WL and Wright A (2014), "New radar observations of temporal and spatial dynamics of the midnight temperature maximum at low latitude and midlatitude", Journal of Geophysical Research: Space Physics. Vol. 119(12), pp. 10,499-10,506.
Abstract: Presented here are several cases of midnight temperature maximum (MTM) observations using the Millstone Hill incoherent scatter radar (ISR) and Arecibo ISR. The MTM, a temperature enhancement in the upper atmosphere (at ~300?km altitude), is a poorly understood phenomenon as observations are sparse. An upward propagating terdiurnal tide and coupling between atmospheric regions may play a large part in the generation of the MTM, yet this phenomenon and its implications are not fully understood. Two nights (6 March 1989 and 12 July 1988) show clear cases of the MTM occurring between 30 and 34°N with amplitudes of ~100?K and at ~18°N with amplitudes of ~40?K. The MTMs occurred later at the higher latitude. Experiments in 2013 also show a clear MTM at 34° and 36°N from 250 to 350?km altitude. The ionospheric measurements presented here demonstrate a new application of a well-established technique to study atmospheric parameters and allow us to study the latitudinal extent of the MTM. The results provide evidence of the phenomenon occurring at latitudes and altitudes not previously sampled by radar techniques, showing that the MTM is not just an equatorial process, but one that can easily reach midlatitudes. Simultaneous measurements with a Fabry-Perot interferometer allow us to compare the neutral temperatures with the ion temperature. Overall, these are key observations that point to large-scale effects that can help constrain model outputs at different heights and latitudes.
BibTeX:
@article{JGRA:JGRA51497,
  author = {Hickey, Dustin A. and Martinis, Carlos R. and Erickson, Philip J. and Goncharenko, Larisa P. and Meriwether, John W. and Mesquita, Rafael and Oliver, William L. and Wright, Ashley},
  title = {New radar observations of temporal and spatial dynamics of the midnight temperature maximum at low latitude and midlatitude},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {12},
  pages = {10,499--10,506},
  url = {http://dx.doi.org/10.1002/2014JA020719},
  doi = {10.1002/2014JA020719}
}
Liu X, Xu J, Zhang S, Jiang G, Zhou Q, Yuan W, Noto J and Kerr R (2014), "Thermospheric planetary wave-type oscillations observed by FPIs over Xinglong and Millstone Hill", Journal of Geophysical Research: Space Physics., August, 2014. Vol. 119(8), pp. 6891-6901.
Abstract: Three-year (2010–2013) observations of thermospheric winds (at ~250?km) by Fabry-Perot interferometers at Xinglong (XL, 40.2°N, 117.4°E) and Millstone Hill (MH, 42.6°N, 71.5°W) are used to study the climatology of atmospheric planetary wave-type oscillations (PWTOs) with periods of 4–19?days. We find that (1) these PWTOs occur more frequently in the months from May to October. They are consistent with the summertime preference of middle-latitude ionospheric electron density oscillations noted in other studies. (2) The month-to-month variations in PWTOs show phase changes between MH and XL, switching from antiphase to in phase when PWTO periods vary from short to long. (3) Typical PWTOs show annual and semiannual variations. The relative intensity of annual over semiannual components for PWTOs is different between XL and MH. (4) Magnetic storms and substorms have little influences on the annual and semiannual variations of the typical PWTO amplitudes. (5) Meridional wind PWTOs with typical periodicity bands around 5, 8, and 16?days appear to be correlated to both solar wind speed and Kp oscillations, suggesting a possible influence of the solar wind corotating interaction regions on neutral wind dynamics.
BibTeX:
@article{Liu2014,
  author = {Liu, Xiao and Xu, Jiyao and Zhang, Shunrong and Jiang, Guoying and Zhou, Qihou and Yuan, Wei and Noto, John and Kerr, Robert},
  title = {Thermospheric planetary wave-type oscillations observed by FPIs over Xinglong and Millstone Hill},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {8},
  pages = {6891--6901},
  url = {http://dx.doi.org/10.1002/2014JA020043},
  doi = {10.1002/2014JA020043}
}
Nicolls MJ, Vadas SL, Aponte N and Sulzer MP (2014), "Horizontal parameters of daytime thermospheric gravity waves and E region neutral winds over Puerto Rico", Journal of Geophysical Research: Space Physics. Vol. 119(1), pp. 575-600.
Abstract: We report on the electron density perturbation amplitudes, periods (up to 60 min), horizontal and vertical wavelengths, phase speeds, and propagation directions of daytime traveling ionospheric disturbances (TIDs) from 115 to 300 km altitude using dual-beam experiments at the Arecibo Observatory (AO), Puerto Rico. As in previous studies, we find a near continuum of waves above the AO. While the TIDs propagate in nearly all directions except purely westward, we find that most propagate southward southeastward. We find that TID amplitudes increase nearly exponentially with increasing period, although with a much smaller slope for periods >30 min. TID amplitudes peak on the bottomside of the F region. Typical vertical wavelengths increase from less than 50 km at low altitudes to ~100–300 km. Horizontal wavelengths increase from ?70–100?km to ?150–500 km over the same altitude range. Median vertical wavelengths, horizontal wavelengths, and periods increase with altitude up to z~<225 km and are approximately constant at higher altitudes. Horizontal phase speeds are >100–150?m/s. We also measure the E region horizontal neutral winds and find that they peak at ?150 m/s near z?105?km in the middle of the day. Wave phase speeds are in general greater than these ambient winds. In addition, by tracing individual wave packets vertically in altitude, we find that a packet's vertical wavelength generally peaks near the altitude where its inferred ion velocity amplitude is maximum. The vertical wavelength generally decreases above this altitude, an observation that is consistent with gravity wave packet theory.
BibTeX:
@article{Nicolls2014,
  author = {Nicolls, Michael J. and Vadas, Sharon L. and Aponte, Nestor and Sulzer, Michael P.},
  title = {Horizontal parameters of daytime thermospheric gravity waves and E region neutral winds over Puerto Rico},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {1},
  pages = {575--600},
  url = {http://dx.doi.org/10.1002/2013JA018988},
  doi = {10.1002/2013JA018988}
}
Sojka JJ, Jensen JB, David M, Schunk RW, Woods T, Eparvier F, Sulzer MP, Gonzalez SA and Eccles JV (2014), " Ionospheric model-observation comparisons: E layer at Arecibo Incorporation of SDO-EVE solar irradiances ", Journal of Geophysical Research: Space Physics., May, 2014. Vol. 119(5), pp. 3844-3856. Wiley-Blackwell.
Abstract: This study evaluates how the new irradiance observations from the NASA Solar Dynamics Observatory (SDO) Extreme Ultraviolet Variability Experiment (EVE) can, with its high spectral resolution and 10?s cadence, improve the modeling of the E region. To demonstrate this a campaign combining EVE observations with that of the NSF Arecibo incoherent scatter radar (ISR) was conducted. The ISR provides E region electron density observations with high-altitude resolution, 300?m, and absolute densities using the plasma line technique. Two independent ionospheric models were used, the Utah State University Time-Dependent Ionospheric Model (TDIM) and Space Environment Corporation's Data-Driven D Region (DDDR) model. Each used the same EVE irradiance spectrum binned at 1?nm resolution from 0.1 to 106?nm. At the E region peak the modeled TDIM density is 20% lower and that of the DDDR is 6% higher than observed. These differences could correspond to a 36% lower (TDIM) and 12% higher (DDDR) production rate if the differences were entirely attributed to the solar irradiance source. The detailed profile shapes that included the E region altitude and that of the valley region were only qualitatively similar to observations. Differences on the order of a neutral-scale height were present. Neither model captured a distinct dawn to dusk tilt in the E region peak altitude. A model sensitivity study demonstrated how future improved spectral resolution of the 0.1 to 7?nm irradiance could account for some of these model shortcomings although other relevant processes are also poorly modeled.
BibTeX:
@article{Sojka2014a,
  author = {Sojka, Jan J. and Jensen, Joseph B. and David, Michael and Schunk, Robert W. and Woods, Tom and Eparvier, Frank and Sulzer, Michael P. and Gonzalez, Sixto A. and Eccles, J. Vincent},
  title = { Ionospheric model-observation comparisons: E layer at Arecibo Incorporation of SDO-EVE solar irradiances },
  journal = {Journal of Geophysical Research: Space Physics},
  publisher = {Wiley-Blackwell},
  year = {2014},
  volume = {119},
  number = {5},
  pages = {3844-3856},
  url = {http://dx.doi.org/10.1002/2013JA019528},
  doi = {10.1002/2013ja019528}
}
Venkatesh K, Rao PR and Fagundes PR (2014), "The role of altitudinal variation of scale height in determining the topside electron density profile over equatorial and low latitude sectors", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 121, Part A(0), pp. 72 - 82.
Abstract: Abstract Studies on the topside electron density profile variations have gained significant importance in the recent past in view of the trans-ionospheric communication and navigation applications particularly over the equatorial and low latitude sectors. The determination of scale height to be used in analytical functions has become more important in estimating the vertical electron density profile in the topside ionosphere. The incoherent scatter radar data over an equatorial station Jicamarca and a low latitude station Arecibo during the high solar activity years 2001 and 2002 are used to estimate the altitudinal dependence of topside ionospheric scale height. These scale height values at different altitudes are used to reconstruct the topside electron density profiles to study the changes in the shape of the topside profile due to the varying scale height values. It has been observed that a closer estimates of the electron density profiles in the topside ionosphere can be derived by using scale height values around 550&#xa0;km over Jicamarca and around 500&#xa0;km over Arecibo. The IRI-2012 modeled electron density profiles have been derived by giving F-layer peak density and height as inputs and those modeled profiles are compared with ISR measured and reconstructed profiles. Further, the scale height values in the topside ionosphere are computed using the IRI-2012 modeled electron and ion temperatures around 550&#xa0;km altitudes over Jicamarca and around 500&#xa0;km altitude over Arecibo. The scale height values thus derived have been used to reconstruct the topside electron density profiles over Jicamarca and Arecibo, the results of which have also been discussed in this paper.
BibTeX:
@article{Venkatesh201472,
  author = {K. Venkatesh and P.V.S. Rama Rao and Paulo R. Fagundes},
  title = {The role of altitudinal variation of scale height in determining the topside electron density profile over equatorial and low latitude sectors},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2014},
  volume = {121, Part A},
  number = {0},
  pages = {72 - 82},
  url = {http://www.sciencedirect.com/science/article/pii/S136468261400234X},
  doi = {10.1016/j.jastp.2014.10.006}
}
Wu Q, Noto J, Kerr R, Kapali S, Riccobono J, Wang W and Talaat ER (2014), "First Palmer and Millstone Hill midlatitude conjugate observation of thermospheric winds", Journal of Geophysical Research: Space Physics., April, 2014. Vol. 119(4), pp. 3016-3028.
Abstract: The first midlatitude conjugate thermospheric wind observations in the American sector showed various degrees of conjugacy between Palmer (64°S, 64°W, magnetic latitude (MLAT) 50°S) and Millstone Hill (42.82°N, 71.5°W, MLAT 53°N) under three different geomagnetic conditions (recovery after a substorm, moderately active, and quiet). The agreement with the National Center for Atmospheric Research's Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations also varies with the geomagnetic activity level. During substorm recovery, the observations at Palmer (PA) and Millstone Hill (MH) both showed strong westward zonal winds, which the standard TIEGCM greatly underestimated. Inadequate ion convection pattern size and lack of effect from Subauroral Polarization Streams (SAPS) may be the cause of the large discrepancy. The TIEGCM with a SAPS model produced stronger westward zonal winds near PA but did not change the zonal wind near MH. The empirical SAPS model needs further refinements. In general, there is better conjugacy with moderate geomagnetic activity levels. The TIEGCM also agrees better with the observations. Under geomagnetically quiet conditions, the meridional winds appear to be less conjugate. The agreement between the observations and model is reasonable. Optical conjugate observations are severely limited by the seasons and weather conditions in the two hemispheres. Yet they are necessary to understanding the thermospheric dynamics in the subauroral region and its relationship with geomagnetic activity levels. The comparisons with TIEGCM are necessary for future model improvements.
BibTeX:
@article{Wu2014,
  author = {Wu, Qian and Noto, John and Kerr, Robert and Kapali, Sudha and Riccobono, Juanita and Wang, Wenbin and Talaat, Elsayed R.},
  title = {First Palmer and Millstone Hill midlatitude conjugate observation of thermospheric winds},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2014},
  volume = {119},
  number = {4},
  pages = {3016--3028},
  url = {http://dx.doi.org/10.1002/2013JA019062},
  doi = {10.1002/2013JA019062}
}
Aponte N, Brum CGM, Sulzer MP and Gonzalez SA (2013), "Measurements of the O+ to H+ transition height and ion temperatures in the lower topside ionosphere over Arecibo for equinox conditions during the 2008-2009 extreme Solar Minimum", Journal of Geophysical Research: Space Physics., July, 2013. Vol. 118, pp. 4465-4470.
Abstract: We present incoherent scatter radar measurements of electron density, electron and ion temperatures and ion composition made at Arecibo Observatory (18.35oN; 66.75oW), which is at a latitude 30oN geomagnetic (or 46.7o dip latitude) during the recent extreme solar minimum of 2007-2009 and find agreement between our data and recent reports of corresponding satellite observations. Both the in situ spacecraft measurements and our ground based radar profiles exhibit unusually low electron densities and cold temperatures. These 2 factors result in an extraordinarily contracted ionosphere and thermosphere. This contraction in the ionosphere in turn causes the O+/H+ transition height to descend, thus the base of the low latitude plasmasphere, or protonosphere, is found at extraordinary low altitudes. We show that during the geomagnetically quiet period of October 2009, the transition height ht, where [O+]=[H+]+[He+], was observed at altitudes as low as 800-820 km during the daytime, and descended as low as 450 km during the night. At night, when Te= Ti=Tn, temperatures below 675 K were measured at 03:00 Atlantic Standard Time (AST). These values are about 100K lower than corresponding temperatures observed by the Arecibo incoherent scatter radar during the previous solar minimum period (1995-1997).
BibTeX:
@article{Aponte2013,
  author = {Aponte, NÈstor and Brum, Christiano G. M. and Sulzer, Michael P. and Gonzalez, Sixto A.},
  title = {Measurements of the O+ to H+ transition height and ion temperatures in the lower topside ionosphere over Arecibo for equinox conditions during the 2008-2009 extreme Solar Minimum},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  pages = {4465-4470},
  url = {http://dx.doi.org/10.1002/jgra.50416},
  doi = {10.1002/jgra.50416}
}
Chen T-J, Wu L-L, Liang J and Zhou QH (2013), "Research and Analysis on Ionospheric Composition Based on Particle Swarm Optimization", Intelligent Computing Theories and Technology - Lecture Notes in Computer Science. , pp. 596-604.
Abstract: A new analysis method for the molecular ion composition is proposed in this paper. The ionospheric data is measured by incoherent scattering radars (ISR). Contrast to the least square method fit (LSF), which is commonly used on ionospheric composition analyses, the particle swarm optimizer (PSO) is introduced to manipulate the data from ISR. The temperature-composition (TC) dependence problem by the LSF is revisited. The parameters of the Standard Particle Swarm Optimization algorithm (SPSO) for ionospheric composition analyses are determined. Experimental results show that PSO presents a better performance comparing with LSF and can be considered as a potential solution to solve ionospheric composition analysis problem.
BibTeX:
@article{Chen2013,
  author = {Tie-Jun Chen and Li-Li Wu and J.J. Liang and Qihou H. Zhou},
  title = {Research and Analysis on Ionospheric Composition Based on Particle Swarm Optimization},
  journal = {Intelligent Computing Theories and Technology - Lecture Notes in Computer Science},
  year = {2013},
  pages = {596-604},
  url = {http://dx.doi.org/10.1007/978-3-642-39482-9_69},
  doi = {10.1007/978-3-642-39482-9_69}
}
Friedman JS, Chu X, Brum CGM and Lu X (2013), "Observation of a thermospheric descending layer of neutral K over Arecibo", Journal of Atmospheric and Solar-Terrestrial Physics., September, 2013. Vol. 104, pp. 253-259.
Abstract: We report on the first observation of a descending layer of atomic potassium (K) in the thermosphere. This observation was made with the K Doppler lidar at the Arecibo Observatory in Puerto Rico (18.35N; 66.75W) on 12 March 2005. The layer was first observed before 08:00 UT(04:00 AST) centered near 145km with the vertical extent up to about 155km, and then it descended to near 126km just over 2h later at dawn. The descent rate of 2.56+-0.38m/s matches the vertical phase speed of the GSWM09-computed semidiurnal tide between 120 and 150km. This also matches the descent rates of the thermospheric semidiurnal tides measured at Arecibo. Although the K density above 120km remains less than 1cm-3, its presence is unequivocal and has strong similarities to the neutral iron (Fe) layers in the thermosphere over 155km recently discovered by lidar observations at McMurdo, Antarctica. The thermospheric K layer is plausibly explained by radiative electron recombination with K+ within a tidal ion layer, which descends with the downward phase progression of the semidiurnal tide. Based on the production rate of K atoms and using current knowledge of tidal ion layer composition, we calculate an electron density of near 5â1e4cm-3 and K+ concentration of 650cm-3 at 135km immediately prior to the layer formation. This discovery of a thermospheric K layer, coupled with the McMurdo discovery of similar Fe layers, may lead to a new approach to studying the thermosphere in the altitude range of about 100-150km with resonance fluorescence lidars.
BibTeX:
@article{Friedman2013,
  author = {Jonathan S. Friedman and Xinzhao Chu and Christiano Garnett Marques Brum and Xian Lu},
  title = {Observation of a thermospheric descending layer of neutral K over Arecibo},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2013},
  volume = {104},
  pages = {253-259},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682613000783},
  doi = {10.1016/j.jastp.2013.03.002}
}
Friedrich M and Fankhauser M (2013), "Time constants in the ionosphere from neural network models", Advances in Space Research. Vol. 51(4), pp. 691-695.
Abstract: Neural network (NN) models for the low latitude and the polar ionosphere from the D- to the F-region were developed which are based on incoherent scatter radar data from Arecibo and EISCAT Svalbard, respectively. The various geophysical input parameters defining the NN are not only the ones that represent the time one wants to predict, but also the geophysical conditions prior to the time of the prediction. The optimum length of these preceding periods are derived for the two models are different, but a period of 60 days is a compromise acceptable for both latitudes. Furthermore from the Arecibo data time constants of electron density decay after sundown are derived which – arguably – are also relevant elsewhere, including the polar latitudes. Whereas at all altitudes the electron densities decay exponentially after sundown, below 300 km there is an additional variation with solar zenith angle.
BibTeX:
@article{Friedrich2013,
  author = {Martin Friedrich and Martin Fankhauser},
  title = {Time constants in the ionosphere from neural network models},
  journal = {Advances in Space Research},
  year = {2013},
  volume = {51},
  number = {4},
  pages = {691-695},
  url = {http://dx.doi.org/10.1016/j.asr.2011.09.020},
  doi = {10.1016/j.asr.2011.09.020}
}
Goncharenko LP, Hsu VW, Brum CGM, Zhang S-R and Fentzke JT (2013), "Wave signatures in the midlatitude ionosphere during a sudden stratospheric warming of January 2010", Journal of Geophysical Research: Space Physics. Vol. 118(1), pp. 472-487.
Abstract: This paper presents a case study of the day-to-day variability in the midlatitude upper atmospheric ion temperature (around 200-400km) with a focus on variability resulting from meteorological forcing. The data are obtained by the Millstone Hill incoherent scatter radar (42.6N, 288.5E) on 18-31 January 2010, in coincidence with a major sudden stratospheric warming. We elucidate oscillations in ion temperature with both tidal periods (8h and 12h) and non-tidal periods (>24h) by analyzing residuals between the observed temperatures and those expected from an empirical model. We present the spatial-temporal development of periodicities in ion temperature and discuss to what degree these periodicities might be related to the sudden stratospheric warming event. The spectral location and temporal evolution of periodicities with 9.9-12.9h and 6.2-7.9h suggest that they are related to the semidiurnal (12h) and terdiurnal (8h) tides that are enhanced during the sudden stratospheric warming. Periodicities with 3-4d and 10-13d are likely related to Rossby waves with 4d and 10d periods, while the strong periodicity observed at 16-17h could result from the nonlinear interaction of the quasi 2d wave with the semidiurnal tide. As planetary waves are not expected to propagate to altitudes of 200–250km, these experimental results raise questions about the potential mechanisms of coupling between the lower and upper atmosphere.
BibTeX:
@article{Goncharenko2013,
  author = {Goncharenko, Larisa P. and Hsu, Vicki W. and Brum, Christiano Garnett Marques and Zhang, Shun-Rong and Fentzke, Jonathan T.},
  title = {Wave signatures in the midlatitude ionosphere during a sudden stratospheric warming of January 2010},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  number = {1},
  pages = {472-487},
  note = {Arecibo author},
  url = {http://dx.doi.org/10.1029/2012JA018251},
  doi = {10.1029/2012JA018251}
}
Gong Y, Zhou Q, Zhang SD, Aponte N, Sulzer M and GonzÀlez SA (2013), "The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 118(8), pp. 5177-5183.
Abstract: We analyze the data derived from the Arecibo incoherent scatter radar measurements to investigate the response of the F region and topside ionosphere to a strong geomagnetic storm that occurred during the period of 5–6 August 2011. The meridional wind was extremely enhanced at the early stage of the storm. The peak velocity reached approximately 300?m/s at an altitude of 340?km, which is seldom seen at the Arecibo latitude. During the storm, the vertical ion drift caused by the meridional wind was positively correlated with that caused by the electric field, which is opposite to the quiet time relationship. The disturbed vertical ion drifts resulted in large ionospheric perturbations in the F and topside regions. Several collapses were observed in hmF2 during the storm night. NmF2 rapidly increased after the storm and then decreased around midnight. At an altitude of 610?km, the concentration of H+ and O+, and the ratio of H+ over electron density all exhibited large variations. The ratio of H+ over electron density changed from less than 10% to more than 80% in a matter of 2?hours in the morning of 6 August. One explanation for such a behavior is that vertical transport dominates over charge exchange late at night due to the lower concentration of O+.
BibTeX:
@article{Gong2013,
  author = {Gong, Yun and Zhou, Qihou and Zhang, Shao Dong and Aponte, NÈstor and Sulzer, Michael and GonzÀlez, Sixto A.},
  title = {The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  number = {8},
  pages = {5177--5183},
  url = {http://dx.doi.org/10.1002/jgra.50502},
  doi = {10.1002/jgra.50502}
}
Gong Y, Zhou Q and Zhang S (2013), "Atmospheric tides in the low-latitude E and F regions and their responses to a sudden stratospheric warming event in January 2010", Journal of Geophysical Research: Space Physics. Vol. 118(12), pp. 7913-7927.
Abstract: An extensive analysis of atmospheric tides in the low-latitude thermosphere and their responses to a major sudden stratospheric warming (SSW) event (18–23 January 2010) is presented. The analysis is based on observational data from the Arecibo dual-beam incoherent scatter radar. Important findings of the present study are as follows. (1) The diurnal tide with an evanescent phase structure dominates the F region meridional wind field. The diurnal tide has a peak amplitude of 45 m/s occurring at about 245 km, and it is very stable throughout the nine consecutive days' observation. Below 114 km, the vertical structures of the diurnal tide in the meridional and zonal components are consistent, which resemble the classical solar S1, 1 tidal mode. (2) The F region semidiurnal tide is much weaker and has larger day-to-day variability than the diurnal tide. In the E region, the semidiurnal amplitudes in the meridional and zonal components grow continuously in the altitude ranges from 106 to 121 km and from 100 to 115 km, respectively. The vertical wavelength of the zonal component is estimated to be 45 km above 100 km, which is close to the solar S2, 4 and S2, 5 tidal modes. (3) The semidiurnal and terdiurnal tides respond strongly to the SSW while the impact that the SSW has on the diurnal tide in the meridional wind is limited. During the SSW event, the amplitudes of the semidiurnal and terdiurnal tides are enhanced in the F region but reduced in the upper E region.
BibTeX:
@article{Gong2013b,
  author = {Gong, Yun and Zhou, Qihou and Zhang, Shaodong},
  title = {Atmospheric tides in the low-latitude E and F regions and their responses to a sudden stratospheric warming event in January 2010},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  number = {12},
  pages = {7913--7927},
  url = {http://dx.doi.org/10.1002/2013JA019248},
  doi = {10.1002/2013JA019248}
}
Hysell D, Nossa E, Aveiro H, Larsen M, Munro J, Sulzer M and Gonzalez S (2013), "Fine structure in midlatitude sporadic E layers", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 103(0), pp. 16-23.
Abstract: Fine structure in midlatitude sporadic E layer patches or “clouds” is apparent in incoherent scatter observations from the Arecibo Radio Telescope. The fine structure is wavelike with predominant horizontal wavelengths as large as about 2–3 km. We attribute the structure to a drift wave instability operating in the collisional regime. A linear, local dispersion relation for the waves is described which predicts growth driven by polarization electric fields in the cloud. A numerical simulation produces wave growth and other features consistent with the dispersion relation, including finite parallel wavenumbers. The kilometric irregularities are thought to be the primary waves from which secondary, meter-scale waves in the layers can form.
BibTeX:
@article{Hysell2013,
  author = {D.L. Hysell and E. Nossa and H.C. Aveiro and M.F. Larsen and J. Munro and M.P. Sulzer and S.A. Gonzalez},
  title = {Fine structure in midlatitude sporadic E layers},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2013},
  volume = {103},
  number = {0},
  pages = {16-23},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682612003033},
  doi = {10.1016/j.jastp.2012.12.005}
}
Laštovi?ka J (2013), "Trends in the upper atmosphere and ionosphere: Recent progress", Journal of Geophysical Research: Space Physics. Vol. 118(6), pp. 3924-3935.
Abstract: The upper atmosphere and embedded ionosphere respond to increasing concentration of greenhouse gases and other drivers of long-term changes and trends. In this paper, the progress reached in investigations of long-term trends in the upper atmosphere and mesosphere in the last 2?years is briefly summarized. First information appeared about trends in electron temperature (positive trend), thermospheric neutral wind (complex pattern), and total electron content (nonnegative trend). Some new information created partial apparent discrepancies, particularly in the case of ion temperature trends. The quantitative discrepancy between observation-based and model-based trends in mesospheric temperatures and in polar mesospheric clouds has largely been removed. The first observations of trends in CO2 concentration in the lower thermosphere suggest a way how to reduce the observation-model difference in the thermosphere and ionosphere. The scenario of trends in the upper atmosphere and ionosphere is now more complete than it was 2?years ago, but still some gaps and discrepancies occur for further investigations.
BibTeX:
@article{Lastovicka2013,
  author = {Laštovi?ka, Jan},
  title = {Trends in the upper atmosphere and ionosphere: Recent progress},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  number = {6},
  pages = {3924--3935},
  url = {http://dx.doi.org/10.1002/jgra.50341},
  doi = {10.1002/jgra.50341}
}
Marinov P, Zhang S and Kutiev I (2013), "Comparison of topside ionosphere scale height modeled by the Topside Sounder Model and incoherent scatter radar ionospheric model", Advances in Space Research., November, 2013. Vol. 52(0), pp. 1717-1725.
Abstract: Abstract The topside ionosphere scale height extracted from two empirical models are compared in the paper. The Topside Sounder Model (TSM) provides directly the scale height (HT), while the incoherent scatter radar ionospheric model (ISRIM) provides electron density profiles and its scale height (HR) is determined by the lowest gradient in the topside part of the profile. HT and HR are presented for 7 ISR locations along with their dependences on season, local time, solar flux F10.7, and geomagnetic index ap. Comparison reveals that HT values are systematically lower than respective HR values as the average offset for all 7 stations is 55&#xa0;km. For the midlatitude stations Arecibo, Shigaraki, and Millstone Hill this difference is reduced to 43&#xa0;km. The range of variations of HR is much larger than that of HT, as the HT range overlaps the lower part of the HR range. Dependences on ap, DoY and LT are much stronger in the ISRIM than in TSM. This results in much larger values of HR at higher ap. Diurnal amplitude of HR is much larger than that of HT, with large maximum of HR at night. The present comparison yields the conclusion that the ISR measurements provide steeper topside Ne profiles than that provided by the topside sounders.
BibTeX:
@article{Marinov2013a,
  author = {Pencho Marinov and Shunrong Zhang and Ivan Kutiev},
  title = {Comparison of topside ionosphere scale height modeled by the Topside Sounder Model and incoherent scatter radar ionospheric model},
  journal = {Advances in Space Research},
  year = {2013},
  volume = {52},
  number = {0},
  pages = {1717-1725},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117713001440},
  doi = {10.1016/j.asr.2013.03.008}
}
Martinis C, Hickey D, Oliver W, Aponte N, Brum CGM, Akmaev R, Wright A and Miller C (2013), "The midnight temperature maximum from Arecibo incoherent scatter radar ion temperature measurements", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. n/a-n/a(0), pp. n/a-n/a.
Abstract: Abstract The midnight temperature maximum (MTM) is studied using ion temperature data from the incoherent scatter radar at the Arecibo Observatory (18.3N, 66.2W). The MTM is characterized by fitting the radar data with a function that takes into account diurnal, semidiurnal and terdiurnal components. Under the hypothesis that the MTM is related to the amplification of the terdiurnal wave, a Gaussian amplification window is included in the fitting to automatically determine the time of occurrence, temporal duration, and amplitude of the MTM observed. This study focused initially on altitudes near 300km, the typical height of MTM observations from Fabry Perot Interferometers (FPIs). Out of the 491 days available between 1967 and 2010 only 82 showed reliable temperature determination throughout the night at this typically bottomside altitude of often low density and sharp density gradient. The analysis was expanded to include 229 usable nights at heights close to 330km and 367km, where better conditions for temperature determination exist. Most of these nights showed an MTM with amplitudes between 20 and 150K and peak occurrence times during local summer months. The seasonal dependence of MTM parameters is also investigated and compared with previous experimental and modeling studies.
BibTeX:
@article{Martinis2013,
  author = {C. Martinis and D. Hickey and W. Oliver and N. Aponte and C. G. M. Brum and R. Akmaev and A. Wright and C. Miller},
  title = {The midnight temperature maximum from Arecibo incoherent scatter radar ion temperature measurements},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2013},
  volume = {n/a-n/a},
  number = {0},
  pages = {n/a-n/a},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682613001442},
  doi = {10.1016/j.jastp.2013.04.014}
}
Mathews JD (2013), "A short history of geophysical radar at Arecibo Observatory", History of Geo- and Space Sciences. Vol. 4(1), pp. 19-33.
Abstract: As Arecibo Observatory (AO) approaches its 50th anniversary, it is appropriate to review the many radars and ionospheric heaters that have been deployed on or near the 305 m dish and to summarize some of the innovative radar-based geophysical research that has resulted. The reasons William E. (Bill) Gordon developed the 305 m Arecibo dish are well known but are briefly reviewed. The early and then more recent radar/feed designs are reviewed as geophysical uses of Arecibo have evolved and as the full potential of the dish and nearby facilities was and is being realized from HF through S-band frequencies. This history surely has some gaps and there are a few mysteries. The community is encouraged to fill these gaps and to help complete the history.
BibTeX:
@article{Mathews2013,
  author = {Mathews, J. D.},
  title = {A short history of geophysical radar at Arecibo Observatory},
  journal = {History of Geo- and Space Sciences},
  year = {2013},
  volume = {4},
  number = {1},
  pages = {19--33},
  url = {http://www.hist-geo-space-sci.net/4/19/2013/},
  doi = {10.5194/hgss-4-19-2013}
}
Pradipta R, Rooker L, Whitehurst L, Lee M, Ross L, Sulzer M, Gonzalez S, Tepley C, Aponte N, See B and Hu K (2013), "Whistler wave-induced ionospheric plasma turbulence: Source mechanisms and remote sensing ", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 103(0), pp. 169 - 175.
Abstract: Abstract We report a series of experiments conducted at Arecibo Observatory in the past, aimed at the investigation of 40.75&#xa0;kHz whistler wave interactions with ionospheric plasmas and the inner radiation belts at L=1.35. The whistler waves are launched from a Naval transmitter (code-named NAU) operating in Aguadilla, Puerto Rico at the frequency and power of 40.75&#xa0;kHz and 100&#xa0;kW, respectively. Arecibo radar, CADI, and optical instruments were used to monitor the background ionospheric conditions and detect the induced ionospheric plasma effects. Four-wave interaction processes produced by whistler waves in the ionosphere can excite lower hybrid waves, which can accelerate ionospheric electrons. Furthermore, whistler waves propagating into the magnetosphere can trigger precipitation of energetic electrons from the radiation belts. Radar and optical measurements can distinguish wave–wave and wave–particle interaction processes occurring at different altitudes. Electron acceleration by different mechanisms can be verified from the radar measurements of plasma lines. To facilitate the coupling of NAU-launched 40.75&#xa0;kHz whistler waves into the ionosphere, we can rely on naturally occurring spread F irregularities to serve as ionospheric ducts. We can also use HF wave-created ducts/artificial waveguides, as demonstrated in our earlier Arecibo experiments and recent Gakona experiments at HAARP. The newly constructed Arecibo HF heater will be employed in our future experiments, which can extend the study of whistler wave interactions with the ionosphere and the magnetosphere/radiation belts as well as the whistler wave conjugate propagation between Arecibo and Puerto Madryn, Argentina.
BibTeX:
@article{Pradipta2013169,
  author = {R. Pradipta and L.A. Rooker and L.N. Whitehurst and M.C. Lee and L.M. Ross and M.P. Sulzer and S. Gonzalez and C. Tepley and N. Aponte and B.Z. See and K.P. Hu},
  title = {Whistler wave-induced ionospheric plasma turbulence: Source mechanisms and remote sensing },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2013},
  volume = {103},
  number = {0},
  pages = {169 - 175},
  note = {Recent Advances in Equatorial, Low- and Mid-latitude Aeronomy },
  url = {http://www.sciencedirect.com/science/article/pii/S1364682613001405},
  doi = {10.1016/j.jastp.2013.04.010}
}
Rapp M, Strelnikova I, Li Q, Engler N and Teiser G (2013), "Charged Aerosol Effects on the Scattering of Radar Waves from the D-Region", Climate and Weather of the Sun-Earth System (CAWSES). Vol. 19, pp. 339-363.
Abstract: Charged aerosol particles are an important contributor to the D-region charge balance and affect the scattering of radar waves. Among these particles are meteoric smoke particles (MSP) which occur at all D-region altitudes and all seasons, and mesospheric ice particles whose occurrence is confined to altitudes of ~80–90 km at polar latitudes during summer. We argue that it is the modification of electron diffusion by the heavy charged aerosol particles which is the prime effect leading to clearly detectable signatures in both incoherent and coherent radar backscatter. In the case of incoherent scatter, it is shown that the presence of charged aerosol particles modifies the incoherent scatter spectrum. Corresponding observations with the EISCAT UHF radar and the Arecibo radar have been used to detect both MSP and ice particles at D-region altitudes and characterize their radii and number densities. In the case of coherent scatter, it is argued that the modified diffusion properties of the D-region electrons lead to small scale structures at the radar Bragg wavelength due to turbulent mixing in combination with a large Schmidt number. To test this theory, calibrated echo strengths of polar mesosphere summer echoes have been measured with the EISCAT radars at TromsÜ (69°N) and Svalbard (78°N) and collocated 53 MHz radars, thus covering frequencies of 53 MHz, 224 MHz, 500 MHz, and 933 MHz. Importantly, the vast majority of these observations show excellent agreement with the corresponding theoretical predictions thus providing strong support for this theory. This theory was subsequently applied to the same data sets in order to derive ice particle radii. Corresponding results are in excellent agreement with independent data sets from satellite-borne and ground-based optical observations. Finally, some suggestions for future investigations are given.
BibTeX:
@article{Rapp2013,
  author = {Rapp, Markus and Strelnikova, Irina and Li, Qiang and Engler, Norbert and Teiser, Georg},
  title = {Charged Aerosol Effects on the Scattering of Radar Waves from the D-Region},
  journal = {Climate and Weather of the Sun-Earth System (CAWSES)},
  year = {2013},
  volume = {19},
  pages = {339-363},
  doi = {10.1007/978-94-007-4348-9_19}
}
Shi JK, Wang Z, Torkar K, Friedrich M, Wang X, Liu C, Guan YB and Zhu GW (2013), "Ionospheric E-F valley observed by a sounding rocket at the low-latitude station Hainan", Annales Geophysicae. Vol. 31(8), pp. 1459-1462.
Abstract: According to the sounding rocket experiment conducted at Hainan ionospheric observatory (19.5° N, 109.1° E), a valley between the E layer and F layer in the ionospheric electron density profile is observed and presented. The sounding rocket was launched in the morning (06:15 LT) on 7 May 2011, and the observed electron density profile outside the valley agrees with the simultaneous observation by the DPS-4 digisonde at the same station. The width of the observed valley was about 42 km, the depth almost 50%, and the altitude of the electron density minimum 123.5 km. This is the first observation of the E–F valley in the low-latitude region in the East Asian sector. The results are also compared with models, and the physical mechanism of the observed valley is discussed in this paper.
BibTeX:
@article{Shi2013,
  author = {Shi, J. K. and Wang, Z. and Torkar, K. and Friedrich, M. and Wang, X. and Liu, C. and Guan, Y. B. and Zhu, G. W.},
  title = {Ionospheric E-F valley observed by a sounding rocket at the low-latitude station Hainan},
  journal = {Annales Geophysicae},
  year = {2013},
  volume = {31},
  number = {8},
  pages = {1459--1462},
  url = {http://www.ann-geophys.net/31/1459/2013/},
  doi = {10.5194/angeo-31-1459-2013}
}
Whitehurst LN, Lee MC and Pradipta R (2013), "Large plasma filaments and geomagnetic field fluctuations excited concomitantly by solar powered microwave transmissions", Physica Scripta. Vol. 2013(T155), pp. 014011.
Abstract: We investigate large-scale, filament-type of ionospheric plasma turbulence produced by a ground-based solar-powered microwave transmission system. It is shown that microwaves can interact with the ionosphere, primarily, in the E region. Electron collisions play key roles in the generation of large-scale fluctuations in ionospheric plasma density and geomagnetic fields via a thermal filamentation instability. The threshold wave field intensities are found to be of~1 V m -1 for the instability. Possible radar detection of microwave-induced ionospheric plasma effects is discussed and planned for our future Arecibo experiments in Puerto Rico.
BibTeX:
@article{Whitehurst2013,
  author = {L N Whitehurst and M C Lee and R Pradipta},
  title = {Large plasma filaments and geomagnetic field fluctuations excited concomitantly by solar powered microwave transmissions},
  journal = {Physica Scripta},
  year = {2013},
  volume = {2013},
  number = {T155},
  pages = {014011},
  url = {http://stacks.iop.org/1402-4896/2013/i=T155/a=014011},
  doi = {10.1088/0031-8949/2013/T155/014011}
}
Yue X, Zhou Q, Raizada S, Tepley C and Friedman J (2013), "Relationship between mesospheric Na and Fe layers from simultaneous and common-volume lidar observations at Arecibo", Journal of Geophysical Research: Atmospheres. Vol. 118(2), pp. 905-916.
Abstract: We compare the mesospheric Na and Fe layers by using simultaneous and common-volume lidar measurements made at the Arecibo Observatory (18.3°N, 66.75°W), Puerto Rico, in 2003. The temporal variations of the two species are highly correlated at practically all heights, although not always positively. Positive correlations occur in the bottom and top sides while negative correlation is observed in a relatively narrow region in the middle part. Chemical and dynamical effects are discussed to interpret this particular relationship between Na and Fe layers. It is shown that gas phase chemistry determines the structure of the Na and Fe layers after the metals are ablated from meteoroids entering the atmosphere. The observed region of negative correlation appears to be slightly lower than that of the expected region of negative correlation based on inert response to dynamics. It appears that such a difference may be due to temperature-dependent chemistry. Overall, the observed correlations between Na and Fe layers can be well explained by their responses to wave dynamics.
BibTeX:
@article{Yue2013,
  author = {Yue, Xianchang and Zhou, Qihou and Raizada, Shikha and Tepley, Craig and Friedman, Jonathan},
  title = {Relationship between mesospheric Na and Fe layers from simultaneous and common-volume lidar observations at Arecibo},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2013},
  volume = {118},
  number = {2},
  pages = {905-916},
  url = {http://dx.doi.org/10.1002/jgrd.50148},
  doi = {10.1002/jgrd.50148}
}
Zawdie KA, Huba JD and Wu T-W (2013), "Modeling 3-D artificial ionospheric ducts", Journal of Geophysical Research: Space Physics. Vol. 118(11), pp. 7450-7457.
Abstract: The injection of powerful HF waves into the ionosphere leads to strong electron heating followed by a pressure perturbation, which can drive electrons along the field line to the conjugate side, creating what is known as an artificial duct. The electron temperature along the duct is above the ambient temperature; the electron density is depleted on the heating side and increased on the conjugate side. Duct formation due to HF heating has previously been studied using a modified version of SAMI2 (Sami2 is Another Model of the Ionosphere). We use a similarly modified version of SAMI3 to examine the effects of zonal E â B drifts on interhemispheric ducts created by heating over Arecibo. We found that the longitudinal E â B drifts, particularly those caused by the zonal neutral winds, significantly suppress the effects of HF heating on the conjugate side, reducing the temperature and density increases by about 90% and 75%, respectively.
BibTeX:
@article{Zawdie2013,
  author = {Zawdie, K. A. and Huba, J. D. and Wu, T.-W.},
  title = {Modeling 3-D artificial ionospheric ducts},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2013},
  volume = {118},
  number = {11},
  pages = {7450--7457},
  url = {http://dx.doi.org/10.1002/2013JA018823},
  doi = {10.1002/2013JA018823}
}
Brum CGM, Tepley CA, Fentzke JT, Robles E, dos Santos PT and Gonzalez SA (2012), "Long-term changes in the thermospheric neutral winds over Arecibo: Climatology based on over three decades of Fabry-Perot observations", Journal of Geophysical Research: Space Physics. Vol. 117(A2), pp. A00H14 (16 pages).
Abstract: We present a study of the climatology of thermospheric neutral wind (TNW) meridional and zonal components measured with the 630.0 nm nightglow Fabry-Perot interferometer at the Arecibo Observatory from 1980 to 2010. We show and discuss the solar and geomagnetic dependencies as well as the long-term trend of the TNW components and their variation over time and season. A main result of this study was the detection of a substantial seasonal and local time dependence of the response of the TNW to solar and geomagnetic activity. In addition, we found that there is a long-term trend in the thermospheric neutral wind, which can be of a larger magnitude than the variation found in the seasonal, solar cycle, and geomagnetic activity influences. A major signature of this trend over the last 30 years was an increase in the meridional northward component up to 1.4 m/s/yr before midnight local time during the summer.
BibTeX:
@article{Brum2012,
  author = {Brum, Christiano Garnett Marques and Tepley, Craig A. and Fentzke, Jonathan T. and Robles, Eva and dos Santos, Pedrina Terra and Gonzalez, Sixto A.},
  title = {Long-term changes in the thermospheric neutral winds over Arecibo: Climatology based on over three decades of Fabry-Perot observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A2},
  pages = {A00H14 (16 pages)},
  url = {http://dx.doi.org/10.1029/2011JA016458},
  doi = {10.1029/2011JA016458}
}
Delgado R, Friedman JS, Fentzke JT, Raizada S, Tepley CA and Zhou Q (2012), "Sporadic metal atom and ion layers and their connection to chemistry and thermal structure in the mesopause region at Arecibo", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 74(0), pp. 11-23.
Abstract: We present an analysis of two separate and distinct sporadic layer events in the mesosphere and lower thermosphere region above the Arecibo Observatory. These layers were observed in both neutral K and ionic Ca+ with lidars, and in electron density with incoherent scatter radar. Temperature profiles were determined from the K lidar. One sporadic event was a high altitude layer, in which both atomic and ion sporadic layers were positioned above 100 km altitude. This represents a relatively common sporadic layer visible in both ions and neutrals at Arecibo. The other observation was less typical, with a lower altitude and more diffuse sporadic E layer, extending from below 90 km to above 95 km, which dissipated coincident with growth of a sporadic neutral K layer. We analyze these separate events using a temperature-dependent chemical model, which employs commonly accepted chemical processes. We find that the model successfully reproduces the high altitude layer of June 12–13, 2002. The result shows a temperature dependence related to the chemical lifetimes of the metallic constituents, and that the neutral layer would not have formed had the temperature profile matched that of the MSIS-90 model. Second, the temperature dependent chemistry model also reproduced K+ in close agreement with electron densities on June 14–15, 2002. However, the modeled neutrals do not agree well with the observation above 90 km, and it likely requires inclusion of dynamical forcing and advection. We speculate that model and observational deficiencies, primarily exclusion of dynamics such as advection and wave interactions, are the likely shortcomings in the failure to reproduce the observations.
BibTeX:
@article{Delgado2012,
  author = {Ruben Delgado and Jonathan S. Friedman and Jonathan T. Fentzke and Shikha Raizada and Craig A. Tepley and Qihou Zhou},
  title = {Sporadic metal atom and ion layers and their connection to chemistry and thermal structure in the mesopause region at Arecibo},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2012},
  volume = {74},
  number = {0},
  pages = {11-23},
  url = {http://dx.doi.org/10.1016/j.jastp.2011.09.004},
  doi = {10.1016/j.jastp.2011.09.004}
}
Echer MS, Echer E, Rigozo N, Brum CGM, Nordemann D and Gonzalez W (2012), "On the relationship between global, hemispheric and latitudinal averaged air surface temperature (GISS time series) and solar activity ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 74(0), pp. 87-93.
Abstract: The air surface temperature is a basic meteorological parameter and its variation is a primary measure of global, regional and local climate changes. In this work, the global, hemispheric and latitudinal averaged air surface temperature time series, obtained from the NASA/Goddard Institute for Space Studies (GISS), and the Sunspot Number (Rz) for the interval 1880-2005, are decomposed in frequency bands through wavelet multi-resolution analysis. We have found a very low correlation between global, hemispheric and latitudinal averaged air surface temperature and Rz in the 11yr solar cycle band (8-16 years) from about 1880 to about 1950. Afterwards the correlation is higher. A very significant correlation (R around 0.57 to 0.80) is found in the about 22 yr solar Hale cycle band (16-32 years) with lags from zero to four years between latitudinal averages air surface temperature and Rz. Therefore it seems that the 22yr magnetic field solar cycle might have a higher effect on Earth's climate than solar variations related to the 11yr sunspot cycle.
BibTeX:
@article{Echer2012,
  author = {M.P. Souza Echer and E. Echer and N.R. Rigozo and C. G. M. Brum and D.J.R. Nordemann and W.D Gonzalez},
  title = {On the relationship between global, hemispheric and latitudinal averaged air surface temperature (GISS time series) and solar activity },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2012},
  volume = {74},
  number = {0},
  pages = {87-93},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682611002756},
  doi = {10.1016/j.jastp.2011.10.002}
}
Fentzke JT, Hsu V, Brum CGM, Strelnikova I, Rapp M and Nicolls M (2012), "D region meteoric smoke and neutral temperature retrieval using the poker flat incoherent scatter radar", Geophysical Research Letters. Vol. 39(21), pp. L21102 (6 pages).
Abstract: This brief note describes the first measurement of the microphysical properties and variability of meteoric smoke particles (MSPs) at high latitude using the Poker Flat ISR (65.1N, 147.5W). We present a novel technique for determining height resolved daytime D region neutral temperatures, which takes into account the presence of charged dust. We discuss the temporal/spatial variability and the relation to meteoric input observed and MSP microphysical properties in the polar mesopause region. The derived nanometer sized MSPs are consistent with size profiles derived previously using radar/rocket techniques and we note that our results imply a lack of heavy cluster ions below 85 km during the observing period. This provides a template for potential use at many other radar sites for the determination of microphysical properties of MSPs and day-time neutral temperature in the D region that show good general agreement with model and satellite temperature data during the observing period.
BibTeX:
@article{Fentzke2012,
  author = {Fentzke, J. T. and Hsu, V. and Brum, C. G. M. and Strelnikova, I. and Rapp, M. and Nicolls, M.},
  title = {D region meteoric smoke and neutral temperature retrieval using the poker flat incoherent scatter radar},
  journal = {Geophysical Research Letters},
  year = {2012},
  volume = {39},
  number = {21},
  pages = {L21102 (6 pages)},
  url = {http://dx.doi.org/10.1029/2012GL053841},
  doi = {10.1029/2012GL053841}
}
Friedman JS, Maldonado-Nieves D, Gonzalez I, Lautenbach J, Chu X, Smith JA and Huang W (2012), "High spectral resolution test and calibration of an ultra-narrowband Faraday anomalous dispersion optical filter for use in daytime mesospheric resonance Doppler lidar", Journal of Atmospheric and Solar-Terrestrial Physics., May, 2012. Vol. 80, pp. 187-194.
Abstract: We present a high-spectral-resolution test and calibration station for precision measurement of ultra-narrow bandwidth optical filters, and how this is used in the processing of daytime measurements from a resonance Doppler potassium lidar at Arecibo. The test station consists of Doppler-free saturation–absorption spectroscopy coupled with a small free-spectral-range Fabry–Perot etalon, which produces a precise measurement of the filter passband over a range of 20&#xa0;GHz (40&#xa0;pm) or more with a resolution of under 2&#xa0;MHz. This setup is used to measure the bandpass function of a Faraday anomalous dispersion optical filter with a band center at 770&#xa0;nm and full width at half maximum of about 3.64&#xa0;GHz (?7.2&#xa0;pm), which is the principal spectral filter in the Arecibo lidar. This bandpass function is then used to calibrate the Doppler-broadened returns from the K lidar. As the Faraday filter passband is narrow enough, the return lidar signals in both the resonance fluorescence and Rayleigh scattering are affected. We describe a calibration process to deconvolve the measured filter function from the return signals in order to achieve accurate temperature measurements. Our approach is demonstrated with actual lidar measurements.
BibTeX:
@article{Friedman2012,
  author = {Jonathan S. Friedman and Darlene Maldonado-Nieves and Israel Gonzalez and Jens Lautenbach and Xinzhao Chu and John A. Smith and Wentao Huang},
  title = {High spectral resolution test and calibration of an ultra-narrowband Faraday anomalous dispersion optical filter for use in daytime mesospheric resonance Doppler lidar},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2012},
  volume = {80},
  pages = {187-194},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682612000314},
  doi = {10.1016/j.jastp.2012.01.017}
}
Gong Y, Zhou Q, Zhang S, Aponte N, Sulzer M and Gonzalez S (2012), "Midnight ionosphere collapse at Arecibo and its relationship to the neutral wind, electric field, and ambipolar diffusion", Journal of Geophysical Research: Space Physics. Vol. 117(A8), pp. n/a-n/a.
Abstract: We report the analysis of “midnight collapse,” a large drop in the F-layer peak height (HmF2) around midnight, observed at Arecibo during Jan. 14–22, 2010. During the nine nights of observations, the first four nights (Jan. 14–17) exhibited modest drops in HmF2 while the last five nights (Jan. 18–22) showed more severe drops. We examine the roles played by the meridional wind, electric field, and ambipolar diffusion in driving the vertical ion motion. The collapse process can be classified into three stages: preconditioning, initial descent, and sustained descent. Severe collapses occur when HmF2 is preconditioned high prior to the collapse. Ambipolar diffusion is most important during the initial descent. Neutral wind and electric field are responsible for sustaining the collapse. During Jan. 18–22, HmF2 was pushed high by the neutral wind before the collapse started. Neutral wind and electric field were in phase during the sustained severe collapses. The diurnal tide of the meridional wind provided the general condition for the collapses. The terdiurnal tide was most important to cause the difference between the two periods in our observation. Previous studies largely emphasized meridional wind being the dominant mechanism causing midnight collapse. Our study suggests that electric field and ambipolar diffusion also play an important role and the former can be the most dominant factor in some cases.
BibTeX:
@article{Gong2012,
  author = {Gong, Yun and Zhou, Qihou and Zhang, Shaodong and Aponte, Nestor and Sulzer, Michael and Gonzalez, Sixto},
  title = {Midnight ionosphere collapse at Arecibo and its relationship to the neutral wind, electric field, and ambipolar diffusion},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2012JA017530},
  doi = {10.1029/2012JA017530}
}
Haldoupis C (2012), "Midlatitude Sporadic E. A Typical Paradigm of Atmosphere-Ionosphere Coupling", Space Science Reviews. Vol. 168(1-4), pp. 441-461.
Abstract: This paper provides a comprehensive update on sporadic E layers that is placed in the context of atmosphere-ionosphere coupling, exemplified here by the fundamental windshear theory processes that govern sporadic E layer formation and variability. Some basics of windshear theory are provided first, followed by a summary of key experimental results, their interpretation and physical understanding. The emphasis is placed on the wind shear control of the diurnal and sub-diurnal variability and altitude descent of sporadic E layers and the key role behind these properties of the diurnal and semidiurnal tides. Furthermore, the paper summarizes recent observations that establish a role also for the planetary waves in sporadic E layer occurrence and long-term variability. The possible mechanisms behind this interaction are examined and evidence is presented which shows that planetary waves affect sporadic E layers indirectly though the amplitude modulation of tides at lower altitudes in the MLT region. Only a brief mention is made about gravity wave effects on sporadic E, which apparently exist but cannot be as crucial in layer forming as thought in the past. There is now enough evidence to suggest that mid- and low-latitude sporadic E is not as “sporadic” as the name implies but a regularly occurring ionospheric phenomenon. This may suggest that the sporadic E layer physics can be incorporated in large-scale atmosphere-ionosphere coupling models.
BibTeX:
@article{Haldoupis2012,
  author = {Haldoupis, Christos},
  title = {Midlatitude Sporadic E. A Typical Paradigm of Atmosphere-Ionosphere Coupling},
  journal = {Space Science Reviews},
  year = {2012},
  volume = {168},
  number = {1-4},
  pages = {441-461},
  doi = {10.1007/s11214-011-9786-8}
}
Huang C, Zhang S, Zhou Q, Yi F and Huang K (2012), "Atmospheric waves and their interactions in the thermospheric neutral wind as observed by the Arecibo incoherent scatter radar", Journal of Geophysical Research: Atmospheres. Vol. 117(D19), pp. n/a-n/a.
Abstract: Atmospheric waves and their interactions in the thermospheric neutral wind are studied based on Arecibo incoherent scatter radar observations. Our analysis suggests that the thermospheric atmosphere is usually disturbed by certain types of waves, including tides, gravity waves, and planetary waves, of which the diurnal tide is almost always the dominant disturbance. Strong interactions (defined as the coexistence of strong positive and negative correlations among the interacting waves) between the diurnal tide and gravity waves are frequently observed during the entire observation period. These strong interactions can persist for several days, although they are highly intermittent. Moreover, the sum and difference interactions between the diurnal tide and gravity waves always occur simultaneously and the energy exchange between the interacting waves is sometimes reversible. In addition to tide–gravity wave interactions, tide–planetary wave and tide–tide interactions are also found in our data. In tide–planetary wave interactions, the tidal oscillations are modulated at the interacting planetary wave periods. A combination of bispectral and correlation analyses verifies the occurrence of nonlinear interactions among different tidal components in the middle thermosphere. Moreover, during tide–tide interactions, the energy transfer trend changes very frequently, indicating that tidal energy is frequently redistributed among different tidal components. Generally, our study provides proof of strong tide–gravity wave, tide–planetary wave, and tide–tide interactions in the middle thermosphere, which has rarely been reported to date.
BibTeX:
@article{Huang2012,
  author = {Huang, Chunming and Zhang, Shaodong and Zhou, Qihou and Yi, Fan and Huang, Kaiming},
  title = {Atmospheric waves and their interactions in the thermospheric neutral wind as observed by the Arecibo incoherent scatter radar},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2012},
  volume = {117},
  number = {D19},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2012JD018241},
  doi = {10.1029/2012JD018241}
}
Hysell DL, Nossa E, Larsen MF, Munro J, Smith S, Sulzer MP and Gonzalez SA (2012), "Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers", Journal of Geophysical Research: Space Physics. Vol. 117(A8), pp. n/a-n/a.
Abstract: Simultaneous observations of an irregular sporadic Elayer from the Arecibo incoherent scatter radar and a coherent scatter radar located on St. Croix are presented. The layers exhibit periodic structuring which is attributed to shear instability in the neutral flow. Estimates of the time-varying vector neutral wind profiles in which the layer was embedded are analyzed and shown to be shear unstable in the Richardson number sense. In addition to the calculation of the Richardson number values, we present an eigenvalue analysis of the model of Miles (1961) and Howard (1961) for the observed wind profiles. The calculated eigenmodes have dominant Kelvin-Helmholtz modes for the estimated flow that are propagating to the southwest with phase speeds near 50 m/s and horizontal wavelengths between 10–15 km. The growth times for the waves would have been as little as about 1 min. These features are in reasonable agreement with the observed of Es-layer structure. The Miles-Howard model has been analyzed extensively in the past using both analytic and numerical techniques, but calculations of eigenmodes for the equations in a case with background winds that have turning and speed shear have not been carried out previously, as far as we know. The difficulties associated with the calculation are related to identifying the fastest growing modes among the large number of modes that satisfy the equations. The technique and the relationship of the solutions to the observed sporadicE layer wave structure are described.
BibTeX:
@article{Hysell2012,
  author = {Hysell, D. L. and Nossa, E. and Larsen, M. F. and Munro, J. and Smith, S. and Sulzer, M. P. and Gonzalez, S. A.},
  title = {Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2012JA017910},
  doi = {10.1029/2012JA017910}
}
England SL, Liu G, Zhou Q, Immel TJ, Kumar KK and Ramkumar G (2012), "On the signature of the quasi-3-day wave in the thermosphere during the January 2010 URSI World Day Campaign", Journal of Geophysical Research: Space Physics. Vol. 117(A6), pp. n/a-n/a.
Abstract: Ultra-fast Kelvin waves with periods of 3–5 days are important in the coupling of the lower atmosphere to the thermosphere and ionosphere. Here we focus on the observations and effects of a 3-day wave during January 2010. As this time period coincides with a stratospheric warming event, a coordinated set of observations with incoherent scatter radars are available. While there is no evidence that the occurrence of this 3-day wave is connected with this event, these observations offer an unprecedented glimpse of the thermospheric conditions during this period, including the first-ever detection of a 3-day wave with an incoherent scatter radar. Using a combination of ground- and space-based observations, we identify an eastward moving zonal wave number-one 3-day equatorial wave that is comprised of a Kelvin wave at the lowest latitudes and a Rossby-gravity wave at higher latitudes. In the equatorial region, the vertical wavelength is ?40 km and the wave peaks in amplitude around 95–100 km altitude. The wave observed here is only seen to propagate to around 105 km altitude. Evidence of an interaction between this wave and the diurnal tide is seen between 82–88 km. The resultant 3-day periodicity in the diurnal tide is seen to propagate up to altitudes of ?150 km. This could have a significant impact on the ionosphere via modulation of the E-region dynamo, thus carrying the 3-day periodicity to higher altitudes.
BibTeX:
@article{JGRA:JGRA21902,
  author = {England, Scott L. and Liu, Guiping and Zhou, Qihou and Immel, Thomas J. and Kumar, Karanam K. and Ramkumar, Geetha},
  title = {On the signature of the quasi-3-day wave in the thermosphere during the January 2010 URSI World Day Campaign},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A6},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2012JA017558},
  doi = {10.1029/2012JA017558}
}
Makela J and Otsuka Y (2012), "Overview of Nighttime Ionospheric Instabilities at Low- and Mid-Latitudes: Coupling Aspects Resulting in Structuring at the Mesoscale", Space Science Reviews. Vol. 168(1-4), pp. 419-440.
Abstract: We present a review of the current state of understanding regarding two classes of irregularities causing mesoscale structuring (hundreds of kilometers) in the nighttime ionosphere at low- and mid-latitudes. Additionally, current state of understanding of equatorial plasma bubbles at low latitudes, and medium-scale traveling ionospheric disturbances at mid latitudes and their relationship to possible seeding from lower altitudes are described. In each case, well-developed linear theories exist to explain the general properties of the irregularities. However, these linear theories have growth rates too low to explain the actual observations, giving rise to the need to invoke seeding mechanisms. We describe the observational databases that have been compiled over the decades and discuss possible coupling and seeding mechanisms that would overcome the low growth rate and explain the observed structuring at the mesoscale. Future research directions are also briefly discussed.
BibTeX:
@article{Makela2012,
  author = {Makela, JonathanJ. and Otsuka, Yuichi},
  title = {Overview of Nighttime Ionospheric Instabilities at Low- and Mid-Latitudes: Coupling Aspects Resulting in Structuring at the Mesoscale},
  journal = {Space Science Reviews},
  year = {2012},
  volume = {168},
  number = {1-4},
  pages = {419-440},
  doi = {10.1007/s11214-011-9816-6}
}
Nikoukar R, Kamalabadi F, Kudeki E and Sulzer M (2012), "On resolution/error trade-offs in incoherent scatter radar measurements", Radio Science. Vol. 47(1), pp. n/a-n/a.
Abstract: In this work, we investigate the performance of amplitude modulated coding schemes in incoherent scatter radar (ISR) measurements in terms of statistical estimation error, range resolution, and signal-to-noise ratio. We approach this goal by formulating the inherent trade-off between estimation error and resolution as mathematical measures for model order selection. These trade-offs are examined on numerical experiments with several amplitude modulated waveforms with different duty cycles. We demonstrate that compared with an unmodulated long pulse, reduced statistical estimation error with similar range resolution, or finer range resolution with similar estimation accuracy can be obtained by incorporating coding schemes.
BibTeX:
@article{Nikoukar2012,
  author = {Nikoukar, Romina and Kamalabadi, Farzad and Kudeki, Erhan and Sulzer, Michael},
  title = {On resolution/error trade-offs in incoherent scatter radar measurements},
  journal = {Radio Science},
  year = {2012},
  volume = {47},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2011RS004685},
  doi = {10.1029/2011RS004685}
}
Pavlov A (2012), "Ion Chemistry of the Ionosphere at E- and F-Region Altitudes: A Review", Surveys in Geophysics. Vol. 33(5), pp. 1133-1172.
Abstract: The current state of knowledge of E- and F-region ion chemistry is reviewed. Considerable attention is given to the progress in the chemistry of unexcited N2+, O2+, NO+, O+(4S), N+, H+, He+, Fe+, Mg+, Na+, Ca+, and K+ ions and electronically excited O+(2D), O+(2P), O+(4P), and O+(2P*) ions. Achievements in our understanding of the role of vibrationally excited N2+, O2+, and NO+ ions in the ionosphere are discussed.
BibTeX:
@article{Pavlov2012,
  author = {Pavlov, A.V.},
  title = {Ion Chemistry of the Ionosphere at E- and F-Region Altitudes: A Review},
  journal = {Surveys in Geophysics},
  year = {2012},
  volume = {33},
  number = {5},
  pages = {1133-1172},
  url = {http://dx.doi.org/10.1007/s10712-012-9189-8},
  doi = {10.1007/s10712-012-9189-8}
}
Pfaff RF (2012), "The Near-Earth Plasma Environment", Space Science Reviews. Vol. 168(1-4), pp. 23- 112.
Abstract: An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth’s plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances.
BibTeX:
@article{Pfaff2012,
  author = {Robert F. Pfaff},
  title = {The Near-Earth Plasma Environment},
  journal = {Space Science Reviews},
  year = {2012},
  volume = {168},
  number = {1-4},
  pages = {23- 112},
  doi = {10.1007/s11214-012-9872-6}
}
Raizada S, Tepley CA, Williams BP and Garcia R (2012), "Summer to winter variability in mesospheric calcium ion distribution and its dependence on Sporadic E at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 117(A2), pp. n/a-n/a.
Abstract: We present a new investigation of the variability in the metallic calcium ion concentration near the mesopause region, and its relation to the electron concentration during summer and winter seasons at the Arecibo Observatory. During the summer months the ion layer is broader, extending to 87-88 km compared with winter months where it occurs above this altitude around midnight. The concentration maximizes to ~200 ions cm-3 around 90-95 km close to midnight during the summer. However, for the winter months, the peak occurs during the early morning hours in thin descending layers above 98 km. Summer to winter variation in the calcium ion to electron ratio displays an average value of ~0.15 and 0.05 during these seasons, respectively. A good correlation between them suggests that Ca+ densities are directly related to the strength of the Sporadic E, which is stronger in the summer. The average abundance of ions is 5.7 â 107 cm-2 and 4.6 â 107 cm-2 during summer and winter months respectively, while that for electrons is 1.2 â 1010 ions cm-2 and 5.8 â 1e9 ion cm-2 for these seasons. Both Ca+ and Ne display strong descending layers at different altitudes during summer and winter. Calcium ion lifetimes against neutralization are a factor of two lower during the summer than in the winter months around 90 km but similar at altitudes exceeding 95 km.
BibTeX:
@article{Raizada2012,
  author = {Raizada, Shikha and Tepley, Craig A. and Williams, Bifford P. and Garcia, Raul},
  title = {Summer to winter variability in mesospheric calcium ion distribution and its dependence on Sporadic E at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A2},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2011JA016953},
  doi = {10.1029/2011JA016953}
}
Sarkhel S, Raizada S, Mathews JD, Smith S, Tepley CA, Rivera FJ and Gonzalez SA (2012), "Identification of large-scale billow-like structure in the neutral sodium layer over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 117(A10), pp. n/a-n/a.
Abstract: We present a rare event that was recorded over Arecibo using sodium (Na) lidar. Billow-like structures with periods of ~60 min were seen in the Na layer above 102 km on the night of 7–8 July 2010. The absence of any high-altitude structure was noted on the following night. Spectral analysis using the Lomb-Scargle technique reveals periods with larger power on the first night as compared to the adjacent one. The keograms derived from a sequence of 557.7 nm airglow images show the passage of a large frontal wave on 7–8 July 2010. Further investigation on the occurrence of neutral instabilities was carried out using mesospheric temperature and horizontal wind obtained from the Sounding of Atmosphere using Broadband Emission Radiometry (SABER) and TIMED Doppler Interferometer (TIDI) instruments onboard the TIMED satellite. A good agreement is observed between the temperatures derived from SABER and ground-based airglow instruments. The mesospheric temperature and horizontal wind profiles allowed the determination of square of the Brunt-VÄisÄlÄ frequency and Richardson number to quantitatively evaluate the possible role of different instabilities in generating this structure. The profile of the former entity reveals that the region is convectively stable during the time when the event was observed. However, the presence of strong shears in the region, where billow-like structures are observed on 7–8 July 2010, is noted along with a Richardson number of 0.22, indicating the likely occurrence of dynamical instability. Thus, the present work suggests that dynamical instability make conditions conducive for billow-like structures in the Na layer above 102 km. The possible role of plasma processes in generating these structures is also discussed.
BibTeX:
@article{Sarkhel2012a,
  author = {Sarkhel, S. and Raizada, Shikha and Mathews, John D. and Smith, Steve and Tepley, Craig A. and Rivera, Francisco J. and Gonzalez, Sixto A.},
  title = {Identification of large-scale billow-like structure in the neutral sodium layer over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2012},
  volume = {117},
  number = {A10},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2012JA017891},
  doi = {10.1029/2012JA017891}
}
Taori A, Raizada S, Ratnam MV, Tepley CA, Nath D and Jayaraman A (2012), "Role of Tropical Convective Cells in the Observed Middle Atmospheric Gravity Wave Properties from Two Distant Low Latitude Stations", Earth Science Research. Vol. 1, pp. 87-97.
Abstract: We investigate the role of convective processes in triggering middle atmospheric gravity waves with the help of simultaneous measurements of middle atmospheric temperature variability from two tropical stations, Gadanki (13.5oN, 79.2oE) and Arecibo (18.3oN, 66.7oW). Our data reveal that some of the wave periods are similar at both locations indicating the source regions of waves to be similar at both the stations. However, the potential energies of short period gravity waves are found to be significantly higher over Gadanki compared to that at Arecibo. The most striking observation is that background wind conditions were similar and convective processes occurred very close to Gadanki compared to Arecibo. In the view absence of other wave sources during the period of observations, we suggest the strength as well as the distance of convective cells from the location of the observations is responsible for the observed differences in gravity wave spectrum and energies.
BibTeX:
@article{Taori2012,
  author = {A. Taori and S. Raizada and M. Venkat Ratnam and C. A. Tepley and D. Nath and A. Jayaraman},
  title = {Role of Tropical Convective Cells in the Observed Middle Atmospheric Gravity Wave Properties from Two Distant Low Latitude Stations},
  journal = {Earth Science Research},
  year = {2012},
  volume = {1},
  pages = {87-97},
  doi = {10.5539/esr.v1n1p87}
}
Wu T-W, Huba JD, Joyce G and Bernhardt PA (2012), "Modeling Arecibo conjugate heating effects with SAMI2", Geophysical Research Letters. Vol. 39(7), pp. L07103 (5 pages).
Abstract: Conjugate heating effects associated with the upcoming Arecibo heater facility are studied using the NRL ionosphere model SAMI2. A density-dependent, localized heating source is included in the electron temperature equation to model ionospheric radiowave heating. Heating effects are examined as a function of the heating timing and the peak density of the unmodified ionosphere (through the F10.7 index). The simulation results suggest that field-aligned duct formation occur during periods of relatively low electron densities (e.g., during the night). The enhancement of the electron temperature and electron density in the conjugate topside ionosphere (~500 km) could reach respective values of ~5% and 25%. Heating losses associated with inelastic electron-neutral (N2) collisions primarily inhibit conjugate effects.
BibTeX:
@article{Wu2012,
  author = {Wu, T.-W. and Huba, J. D. and Joyce, G. and Bernhardt, P. A.},
  title = {Modeling Arecibo conjugate heating effects with SAMI2},
  journal = {Geophysical Research Letters},
  year = {2012},
  volume = {39},
  number = {7},
  pages = {L07103 (5 pages)},
  url = {http://dx.doi.org/10.1029/2012GL051311},
  doi = {10.1029/2012GL051311}
}
Brum CGM, Rodrigues FdS, dos Santos PT, Matta AC, Aponte N, Gonzalez SA and Robles E (2011), "A modeling study of foF2 and hmF2 parameters measured by the Arecibo incoherent scatter radar and comparison with IRI model predictions for solar cycles 21, 22, and 23", Journal of Geophysical Research: Space Physics. Vol. 116(A3), pp. n/a-n/a.
Abstract: This work presents the results of a local empirical model that describes the behavior of the ionospheric F2 region peak. The model was developed using nearly 25 years of incoherent scatter radar (ISR) measurements made at the Arecibo Observatory (AO) between 1985 and 2009. The model describes the variability of the F2 peak frequency (foF2) and F2 peak height (hmF2) as a function of local time, season, and solar activity for quiet-to-moderate geomagnetic activity conditions (Kp < 4+). Our results show that the solar activity control of hmF2 and foF2 over Arecibo can be better described by a new proxy of the solar flux (F107P), which is presented here. The variation of hmF2 parameter with F107P is virtually linear, and only a small saturation of the foF2 parameter is observed at the highest levels of solar flux. The winter anomaly and asymmetries in the variation of the modeled parameters between equinoxes were detected during the analyses and have been taken into account by the AO model. Comparisons of ISR data with international reference ionosphere (IRI) model predictions indicate that both CCIR and URSI modes overestimate foF2 during the daytime and underestimate it at night. As expected, this underestimation is not observed in the AO model. Our analyses also show that the hmF2 parameter predicted by the IRI modes shows a saturation point, which causes hmF2 to be underestimated at high solar activity. The underestimation increases with higher levels of solar activity. Finally, we also found that IRI predictions of the seasonal variability of foF2 and hmF2 over Arecibo can be improved by using a small correction that varies with solar activity and local time.
BibTeX:
@article{Brum2011,
  author = {Brum, Christiano Garnett Marques and Rodrigues, Fabiano da Silveira and dos Santos, Pedrina Terra and Matta, Aleshka Carrion and Aponte, Nestor and Gonzalez, Sixto A. and Robles, Eva},
  title = {A modeling study of foF2 and hmF2 parameters measured by the Arecibo incoherent scatter radar and comparison with IRI model predictions for solar cycles 21, 22, and 23},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A3},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010JA015727},
  doi = {10.1029/2010JA015727}
}
Chau J, Goncharenko L, Fejer B and Liu H-L (2011), "Equatorial and Low Latitude Ionospheric Effects During Sudden Stratospheric Warming Events", Space Science Reviews. Vol. 168, pp. 385-417.
Abstract: There are several external sources of ionospheric forcing, including these are solar wind-magnetospheric processes and lower atmospheric winds and waves. In this work we review the observed ion-neutral coupling effects at equatorial and low latitudes during large meteorological events called sudden stratospheric warming (SSW). Research in this direction has been accelerated in recent years mainly due to: (1) extensive observing campaigns, and (2) solar minimum conditions. The former has been instrumental to capture the events before, during, and after the peak SSW temperatures and wind perturbations. The latter has permitted a reduced forcing contribution from solar wind-magnetospheric processes. The main ionospheric effects are clearly observed in the zonal electric fields (or vertical EâB drifts), total electron content, and electron and neutral densities. We include results from different ground- and satellite-based observations, covering different longitudes and years. We also present and discuss the modeling efforts that support most of the observations. Given that SSW can be forecasted with a few days in advance, there is potential for using the connection with the ionosphere for forecasting the occurrence and evolution of electrodynamic perturbations at low latitudes, and sometimes also mid latitudes, during arctic winter warmings.
BibTeX:
@article{Chau2012,
  author = {Chau, JorgeL. and Goncharenko, LarisaP. and Fejer, BelaG. and Liu, Han-Li},
  title = {Equatorial and Low Latitude Ionospheric Effects During Sudden Stratospheric Warming Events},
  journal = {Space Science Reviews},
  year = {2011},
  volume = {168},
  pages = {385-417},
  doi = {10.1007/s11214-011-9797-5}
}
Cohen MH and Lane NF (2011), "William Edwin Gordon 1918-2010", NAS Biographical Memoir. Vol. n/a-n/a, pp. 22 pages. National Academy of Sciences.
Abstract: William Edwin Gordon was born in Patterson, New Jersey, on January 8, 1918. He studied meteorology at New York University while in the Army Air Corps during World War II, and then was engaged in radio wave propagation studies until the war ended. After the war, he continued these studies at the University of Texas in Austin, and in 1948 moved to Ithaca, New York, for graduate study in electrical engineering at Cornell. He stayed at Cornell after obtaining his Ph.D. degree in 1953. In 1958 he conceived of a large vertically directed radar to measure the electron density and temperature in the high ionosphere. This became the Arecibo project, whose study and construction in Puerto Rico he organized, and the giant system was dedicated in 1963. He became its first director. In 1965 he moved to Rice University as dean of science and engineering, later provost and vice president. He was active in ionospheric research into the 1990s. He died in Ithaca, New York, in February 2010; his survivors include two children, Nancy Ward and Larry Gordon; four grandchildren; three great-grandchildren; and his wife, Elizabeth Bolgiano Gordon of Ithaca. His first wife of 61 years, Elva Gordon, died in 2001.
BibTeX:
@article{Cohen2011,
  author = {Cohen, Marshall H and Lane, Neil F},
  title = {William Edwin Gordon 1918-2010},
  journal = {NAS Biographical Memoir},
  publisher = {National Academy of Sciences},
  year = {2011},
  volume = {n/a-n/a},
  pages = {22 pages},
  url = {http://nas.nasonline.org/site/DocServer/Gordon_William.pdf?docID=77361}
}
da Costa AM, Domingues MO, Mendes O and Brum CGM (2011), "Interplanetary medium condition effects in the South Atlantic Magnetic Anomaly: A case study ", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 73(11-12), pp. 1478-1491.
Abstract: One way to investigate the magnetosphere–ionosphere coupling is through the simultaneous observation of different parameters measured at different locations of the geospace environment and try to determine some relationships among them. The main objective of this work is to examine how the solar energetic particles and the interplanetary medium conditions may affect the space and time configuration of the ring current at low-latitudes and also to get a better understanding on how these particles interfere with the lower ionosphere in the South Atlantic Magnetic Anomaly region (SAMA). To accomplish this, the cosmic noise absorption (CNA) and the horizontal component of the Earth's magnetic field data measured from sites located in the SAMA region were compared with the proton and electron fluxes, interplanetary medium conditions (solar wind and the north–south component of the interplanetary magnetic field measured on board satellites), the SYM-H index and magnetometer data from Kakioka (KAK-Japan), located significantly outside the SAMA region. The time series analyzed correspond to the geomagnetic disturbance that occurred on August 25-30, 1998. The analysis was performed by implementing wavelet techniques, with particular attention to singularities detection, which highlights the presence of transient signals. The results are discussed in terms of the first three wavelet decomposition levels of the parameters. The magnitude of wavelet coefficients of the solar wind and proton flux at the two energy ranges analyzed is timely well correlated, indicating that these two signals are energetically linked. The larger wavelet coefficient amplitude of KAK and VSS magnetograms shows time delays that are compatible with an asymmetric configuration of the ring current, considering that at the storm time, VSS was at the dawn sector of the magnetosphere and KAK at the dusk side. The wavelet analysis of CNA signals reveals that the signal may be sensitive to the ionization produced by energetic electrons and protons as well. The time delays observed in wavelet coefficients may give an indication of the different accelerating process to which the particles are submitted when traveling along the magnetic field lines, from higher to lower latitudes, and the likely contribution of these particles to the ionization measured as an absorption of the cosmic noise in the lower ionosphere.
BibTeX:
@article{Costa2011,
  author = {Aracy Mendes da Costa and Margarete Oliveira Domingues and Odim Mendes and Christiano Garnett Marques Brum},
  title = {Interplanetary medium condition effects in the South Atlantic Magnetic Anomaly: A case study },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2011},
  volume = {73},
  number = {11-12},
  pages = {1478-1491},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682611000113},
  doi = {10.1016/j.jastp.2011.01.010}
}
Cotts BRT (2011), "Global Quantification of Lighting-Induced Electron Precipition Using Very Low Frequency Remote Sensing". Thesis at: STANFORD UNIVERSITY., 03/2011, 2011.
Review: Observations of lightning-induced electron precipitation (LEP) events at three geographic regions show characteristics which systematically vary with both longitude and hemisphere. These observations are quantitatively interpreted with the use of a novel model of atmospheric backscatter designed to be used to predict the characteristics of LEP events at any longitude and mid-latitude L-shell by accounting for the effects of precipitating electrons which are backscattered from the atmosphere.

The new model of atmospheric backscatter (ABS) is based upon the calculation of ~16,000 individual atmospheric backscatter responses for monoenergetic, monodirectional electron beams with a single incident pitch angle using a Monte Carlo model of atmospheric interactions. The model tracks the full gyration of each individual precipitating electron around the magnetic field line as it enters the atmosphere, accounting for the dynamic friction force and angular diffusion as well as the production of new electrons via ionization. The ABS model includes the effects of the asymmetric magnetic field in calculations of the pitch angle of backscattered electrons entering the conjugate hemisphere and accounts for the different strength of the magnetic field at conjugate points of the same field line. This magnetic field difference causes the equatorial loss cone angle to vary greatly between hemispheres and with longitude, which results in significant and systematic differences in LEP signatures at various locations.

A realistic distribution of precipitating electrons is inserted into the ABS model by calculating the energy and pitch angle distribution, which results from the resonant interactions of a lightning-initiated magnetospherically reflecting whistler wave with trapped radiation belt particles. This calculation is accomplished by extensive magnetospheric ray-tracing, accounting for Landau damping as well as spatial and temporal dispersion of the whistler wave.

This distribution of precipitating electrons is then inserted into the ABS model at three separate longitudes ('N1=260_ E/N, 'N2=290_ E/N, and 'S1=295_ E/S, corresponding to the Central United States, the East Coast of the United States, and Palmer, Antarctica, respectively) and the deposition results are compared with VLF remote sensing data collected on nearly north-south great circle paths (GCPs) allowing for isolation of longitudinal effects on LEP. Results predicted by the model and confirmed by data indicate that all four primary LEP characteristics exhibit longitudinal and hemispheric dependencies which can be explained in terms of backscatter of precipitating electrons from the atmosphere. The mean observed LEP onset delay (Dt) exhibits a hemispheric dependence at these longitudes with events in the northern hemisphere delayed by one bounce period relative to direct precipitation and advanced by one-half bounce period in the southern hemisphere. The mean observed onset duration (td) exhibits a longitudinal dependence with events observed at 'N1 and 'S2 persisting for three bounce periods, and at 'N2for two bounce periods. The amplitude change (DA) and recovery time (tr) also show a longitudinal and hemispheric dependence based upon the relative sizes of the loss cones at different longitudes. LEP events produced at 'N1 have consistently larger perturbation magnitudes than at 'N2 , and observed recovery times at 'N2 are longer than at 'N1 which are still longer than at 'S2 . All of these results are explained in terms of backscatter of precipitating electrons from the atmosphere and the ABS model shows that by accounting for atmospheric backscatter it is possible to accurately predict all the observable characteristics of LEP events. Furthermore, by combining these effects with previously calculated radiation belt electron loss rates due to lightning at a single location, it is possible to estimate the global loss of radiation belt electrons due to lightning.

BibTeX:
@phdthesis{Cotts2011,
  author = {Cotts, Benjamin R. T.},
  title = {Global Quantification of Lighting-Induced Electron Precipition Using Very Low Frequency Remote Sensing},
  school = {STANFORD UNIVERSITY},
  year = {2011},
  url = {http://vlf.stanford.edu/sites/default/files/publications/Cotts_Thesis_OnlineVersion.pdf}
}
Eccles V, Thompson J, Sojka JJ, Vo H and Gonzalez S (2011), "Assessment of Ionospheric Models package for the Community Coordinated Modeling Center: Climatology", Space Weather. Vol. 9(1), pp. n/a-n/a.
Abstract: Due to the paucity of ionospheric density observations, ionospheric models are important for constructing the day-to-day 3-D specifications of electron density. Quality specifications are required to mitigate ionospheric influences on modern GPS navigation and communications technologies. The Arecibo Radar Observatory Incoherent Scatter Radar has provided F region electron density profiles spanning 50 years and 4 solar cycles. We have collected, reduced, and cleaned the Arecibo radar electron density profiles to create a "ground truth database" for use in the metric assessment of the accuracy of empirical and physics-based ionospheric models. The metrics and skill assessments within this Assessment of Ionospheric Models package are described herein. The assessment package will be implemented at the Community Coordinated Modeling Center to provide a Web-based generator of metrics and skill scores based on several electron density profile parameters: peak density values, peak density altitudes, and the shape of the electron density profile with altitude. This Assessment of Ionospheric Models package will greatly assist in improving current models of the ionosphere.
BibTeX:
@article{Eccles2011,
  author = {Eccles, Vince and Thompson, Jonathan and Sojka, Jan J. and Vo, Hien and Gonzalez, Sixto},
  title = {Assessment of Ionospheric Models package for the Community Coordinated Modeling Center: Climatology},
  journal = {Space Weather},
  year = {2011},
  volume = {9},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010SW000596},
  doi = {10.1029/2010SW000596}
}
Eccles V, Vo H, Thompson J, Gonzalez S and Sojka JJ (2011), "Database of electron density profiles from Arecibo Radar Observatory for the assessment of ionospheric models", Space Weather. Vol. 9(1), pp. n/a-n/a.
Abstract: We describe the reduction of the Arecibo Observatory incoherent scatter radar electron density profiles from 1966 to 2006 into a standardized database of electron density profiles useful for the assessment of ionospheric models. The database of electron density profiles covers approximately 700 days of observation over nearly 4 solar cycles and all seasons. These data are averaged into climatological conditions with special attention at maintaining a normal profile shape in altitude. The reduced profile database and the climatological average profiles are provided to the Community Coordinated Modeling Center for open access by the community and their efforts to generate ionosphere model metrics and skill scores.
BibTeX:
@article{Eccles2011a,
  author = {Eccles, Vince and Vo, Hien and Thompson, Jonathan and Gonzalez, Sixto and Sojka, Jan J.},
  title = {Database of electron density profiles from Arecibo Radar Observatory for the assessment of ionospheric models},
  journal = {Space Weather},
  year = {2011},
  volume = {9},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010SW000591},
  doi = {10.1029/2010SW000591}
}
Balcerak E (2011), "Currents can be driven in the polar ionosphere", Eos, Transactions American Geophysical Union. Vol. 92(31), pp. 264-264.
Abstract: The study of ionospheric heaters that induce controlled modifications in the ionosphere allows better understanding of effects driven naturally by solar activity in the ionosphere and the radiation belts. Previous ionospheric heaters at the Earth's poles have generated ultralow-frequency, extremely low frequency, and very low frequency waves in the ionosphere's D andE regions by modulating the auroral electrojet, the strong horizontal currents that naturally flow in the D and E regions at high latitudes. Now Papadopoulos et al. present theoretical and computational results that indicate that using high-frequency heating, low-frequency ionospheric currents can also be generated at F region altitudes, independent of the presence or absence of electrojet currents. The new technique, whose validity has been confirmed tentatively in recent polar experiments, allows generation of low-frequency waves by midlatitude heaters, such as the one under construction in Arecibo, Puerto Rico, and their subsequent injection in the inner radiation belt. It will permit for the first time the study of the interaction of artificially generated low-frequency waves with multi-MeV protons trapped in the inner belt and their precipitation rates in the South Atlantic anomaly region. (Geophysical Research Letters, doi:10.1029/2011GL047368, 2011)
BibTeX:
@article{EOST:EOST17996,
  author = {Balcerak, Ernie},
  title = {Currents can be driven in the polar ionosphere},
  journal = {Eos, Transactions American Geophysical Union},
  year = {2011},
  volume = {92},
  number = {31},
  pages = {264--264},
  url = {http://dx.doi.org/10.1029/2011EO310007},
  doi = {10.1029/2011EO310007}
}
Fentzke JT, Sulzer MP and Gonzalez SA (2011), "The effects of Bhatnagar-Gross-Krook, Brownian, and hard-sphere ion-neutral collision models on the incoherent scatter spectrum in the E region", Journal of Geophysical Research: Space Physics. Vol. 116(A1), pp. n/a-n/a.
Abstract: We revisit the theory developed by Hagfors and Brockelman (1971). The purpose of this work is to improve the understanding of variations in the incoherent scatter spectrum in the lower E region of the ionosphere between approximately 85 and 150 km under the assumption of Brownian, Bhatnagar-Gross-Krook, and hard-sphere collisions in the absence of magnetic field influences, for operating frequencies representative of the chain of NSF-sponsored incoherent scatter radars (ISRs), which range from 50 to 1290 MHz. Also, we extend the computationally limited examples in Hagfors and Brockelman (1971) as well as demonstrate the feasibility of making the E region measurements at the Arecibo Observatory ISR in Puerto Rico (18°N, 67°W). We confirm the theory from Hagfors and Brockelman (1971) and show that the original nondimensionalized examples were representative of spectra at approximately 95, 105, and 150 km. Additionally, our results show that there is more variability in the incoherent scatter spectrum for the aforementioned ion-neutral collision approximations, especially in the 90–105 km altitude range compared to the results shown by Hagfors and Brockelman (1971). This is most likely due to the greater computational resources currently available and the more up-to-date models for atmospheric and ionospheric conditions derived from MSIS-00 and IRI-07, respectively. These findings suggest that future work is needed to evaluate the impact, if any, on the ionospheric parameters derived using each of the three ion-neutral collision approximations.
BibTeX:
@article{Fentzke2011,
  author = {Fentzke, J. T. and Sulzer, M. P. and Gonzalez, S. A.},
  title = {The effects of Bhatnagar-Gross-Krook, Brownian, and hard-sphere ion-neutral collision models on the incoherent scatter spectrum in the E region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010JA015340},
  doi = {10.1029/2010JA015340}
}
Garzon DP, Brum CGM, Echer E, Aponte N, Sulzer MP, Gonzalez SA, Kerr RB and Waldrop L (2011), "Response of the topside ionosphere over Arecibo to a moderate geomagnetic storm", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 73(11-12), pp. 1568-1574.
Abstract: We analyze the data obtained using the Arecibo incoherent scatter radar to examine the response of the topside ionosphere to a moderate geomagnetic storm that occurred during the period March 7-11, 2008. During this time period a magnetic storm with a non-monotonic main phase decrease in the Dst index occurred. The recovery phase also exhibited a secondary Dst decrease. During the initial phase of the storm, Te and Ti increased coincident with the arrival of the solar wind. The main phase registered an increase in proton concentration proportional to Ne while temperatures reached the lowest values. Variations in O+ concentration were not significant but a reduction in helium fraction was observed. Soon after the peak of the storm, the transition height between the topside ionosphere and the protonosphere, where H+ ions dominate composition, was lower than would be expected during quiet conditions and this behavior lasted for approximately 12h.
BibTeX:
@article{Garzon2011,
  author = {Diana Prado Garzon and Christiano Garnett Marques Brum and Ezequiel Echer and Nestor Aponte and Michael P. Sulzer and Sixto A. Gonzalez and Robert B. Kerr and Lara Waldrop},
  title = {Response of the topside ionosphere over Arecibo to a moderate geomagnetic storm},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2011},
  volume = {73},
  number = {11-12},
  pages = {1568-1574},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682611000630},
  doi = {10.1016/j.jastp.2011.02.016}
}
Gong Y and Zhou Q (2011), "Incoherent scatter radar study of the terdiurnal tide in the E- and F-region heights at Arecibo", Geophysical Research Letters. Vol. 38(15), pp. n/a-n/a.
Abstract: We report the analysis of the terdiurnal tide in the meridional wind from 90 to 350 km at a low latitude station. Our data is based on nine days of consecutive observation made by the Arecibo incoherent scatter radar during January 14–23, 2010. The terdiurnal tide is observed to be prominent at E-region heights in the first four days (Jan. 14–18) and at the F-region heights in the last five days (Jan. 18–23). The terdiurnal tide is among the two strongest tidal components in both regions. The vertical wavelength of the terdiurnal tide is about 100 km, and 950 km, for the altitude range of 128 to 142 km, and 180 to 320 km, respectively. The F-region terdiurnal tide amplitude is found to be well correlated with the background meridional wind in the lower F-region. Our analysis does not reveal any evidence that non-linear interaction between diurnal and semidiurnal tides is important for the F-region terdiurnal tide.
BibTeX:
@article{Gong2011,
  author = {Gong, Yun and Zhou, Qihou},
  title = {Incoherent scatter radar study of the terdiurnal tide in the E- and F-region heights at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2011},
  volume = {38},
  number = {15},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2011GL048318},
  doi = {10.1029/2011GL048318}
}
Papadopoulos K, Gumerov NA, Shao X, Doxas I and Chang CL (2011), "HF-driven currents in the polar ionosphere", Geophysical Research Letters. Vol. 38(12), pp. n/a-n/a.
Abstract: Polar ionospheric heaters have generated ULF/ELF/VLF waves by modulating the auroral electrojet at D/E region altitudes. We present theoretical/computational results indicating that modulated F-region HF heating can generate ionospheric currents even in the absence of electrojet currents. The ELF currents are driven in a two-step process. First, the pressure gradient associated with F-region electron heating drives a local diamagnetic current. This acts as an antenna to inject Magneto-Sonic (MS) waves in the ionospheric plasma. Second, the electric field of the magneto-sonic wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that injects waves in the Earth-Ionosphere Waveguide below and Shear Alfven waves upwards to the conjugate regions. The paper examines the scaling and limitations of the concept and suggests proof-of-principle experiments using the HAARP ionospheric heater.
BibTeX:
@article{GRL:GRL28066,
  author = {Papadopoulos, K. and Gumerov, N. A. and Shao, X. and Doxas, I. and Chang, C. L.},
  title = {HF-driven currents in the polar ionosphere},
  journal = {Geophysical Research Letters},
  year = {2011},
  volume = {38},
  number = {12},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2011GL047368},
  doi = {10.1029/2011GL047368}
}
Hysell DL, Yokoyama T, Nossa E, Hedden RB, Larsen MF, Munro J, Smith S, Sulzer MP and Gonzalez SA (2011), "Radar and Optical Observations of IrregularMidlatitude Sporadic E Layers Beneath MSTIDs", Aeronomy of the Earth, Atmosphere and Ionosphere. Vol. 19, pp. 269-281.
Abstract: An irregular sporadic E ionization layer was observed by the Arecibo incoherent scatter radar and a coherent scatter radar imager located on St. Croix during the passage of an MSTID observed by the Boston University all-sky camera in 630 nm imagery. The MSTID in question was not very intense and was barely detectable in the vertical F region plasma drifts measured by Arecibo. The intensity of the coherent scatter from small-scale irregularities in the sporadic E layer appeared nonetheless to be modulated by the MSTID and was strongest in the F region airglow crests, mapped along magnetic field lines to the E region volume being observed. The coherent scatter Doppler shifts were highly correlated with altitude displacements in the sporadic E layer, and the sign of the correlation was controlled by the sign of the background zonal electric field. The MSTID did not appear to modulate the morphology of the sporadic E layer irregularities themselves, which took the form of convective rolls and which drifted with the ambient neutral wind.
BibTeX:
@article{Hysell2011,
  author = {David L. Hysell and Tatsuhiro Yokoyama and Eliana Nossa and Russell B. Hedden and Miguel F. Larsen and John Munro and Steven Smith and Michael P. Sulzer and and Sixto A. Gonzalez},
  title = {Radar and Optical Observations of IrregularMidlatitude Sporadic E Layers Beneath MSTIDs},
  journal = {Aeronomy of the Earth, Atmosphere and Ionosphere},
  year = {2011},
  volume = {19},
  pages = {269-281},
  doi = {10.1007/978-94-007-0326-1_19}
}
Klimenko MV, Klimenko VV, Ratovsky KG, Goncharenko LP, Sahai Y, Fagundes PR, de Jesus R, de Abreu AJ and Vesnin AM (2011), "Numerical modeling of ionospheric effects in the middle- and low-latitude F region during geomagnetic storm sequence of 9-14 September 2005", Radio Science. Vol. 46(3), pp. n/a-n/a.
Abstract: This study presents the Global Self-Consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) numerical simulations of the 9–14 September 2005 geomagnetic storm effects in the middle- and low-latitude ionosphere. Recent modifications to the GSM TIP model include adding an empirical model of high-energy electron precipitation and introducing a high-resolution (1 min) calculation of region 2 field-aligned currents and a cross-cap potential difference. These modifications resulted in better representation of such effects as penetration of the magnetospheric convection electric field to lower latitudes and the overshielding. The model also includes simulation of solar flare effects. Comparison of model results with observational data at Millstone Hill (42.6°N, 71.5°W, USA), Arecibo (18.3°N, 66.8°W, Puerto Rico), Jicamarca (11.9°S, 76.9°W, Peru), Palmas (10.2°S, 48.2°W, Brazil), and San Jose Campos (23.2°S, 45.9°W, Brazil) shows good agreement of ionospheric disturbances caused by this storm sequence. In this paper we consider in detail the formation mechanism of the additional layers in an equatorial ionosphere during geomagnetic storms. During geomagnetic storms, the nonuniform in height zonal electric field is generated at the geomagnetic equator. This electric field forms the additional layers in the F region of equatorial ionosphere.
BibTeX:
@article{Klimenko2011,
  author = {Klimenko, M. V. and Klimenko, V. V. and Ratovsky, K. G. and Goncharenko, L. P. and Sahai, Y. and Fagundes, P. R. and de Jesus, R. and de Abreu, A. J. and Vesnin, A. M.},
  title = {Numerical modeling of ionospheric effects in the middle- and low-latitude F region during geomagnetic storm sequence of 9-14 September 2005},
  journal = {Radio Science},
  year = {2011},
  volume = {46},
  number = {3},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010RS004590},
  doi = {10.1029/2010RS004590}
}
Klimenko MV, Klimenko VV, Ratovskii KG and Goncharenko LP (2011), "Ionospheric effects of geomagnetic storms at mid latitudes", Russian Journal of Physical Chemistry B, Focus on Physics. Vol. 5, pp. 24-34.
Abstract: Previously, we studied the ionospheric effects of the sequence of geomagnetic storms on September 9–14, 2005 using a global self-consistent model “Thermosphere-Ionosphere-Protonosphere” (GSM TIP). Differences between the predicted and observed effects of the ionospheric storms may be due to the use of the three-hour K p index of geomagnetic activity in modeling the time dependence of model input parameters, use of the dipole approximation of the geomagnetic field, and disregard in simulations for solar flares that occurred during this period. We tried to eliminate two of these three reasons. First, we used the A E index of geomagnetic activity with minute resolution in modeling the time dependence of the model input parameters. Second, we took into account the effects of solar flares. In addition, GSM TIP model was supplemented by an empirical model describing the precipitation of high-energy electrons. The results of the simulation of the behavior of various ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill, and Arecibo stations on September 9 and 10, 2005 in the new formulation of the problem, presented in the current work, are in better agreement with the available experimental data than the results of previous calculations.
BibTeX:
@article{Klimenko2011a,
  author = {Klimenko, M V and Klimenko, V V and Ratovskii, K G and Goncharenko, L P},
  title = {Ionospheric effects of geomagnetic storms at mid latitudes},
  journal = {Russian Journal of Physical Chemistry B, Focus on Physics},
  year = {2011},
  volume = {5},
  pages = {24-34},
  doi = {10.1134/s1990793111030092}
}
Klimenko MV, Klimenko VV, Ratovsky KG and Goncharenkod LP (2011), "Ionospheric Effects Caused by the Series of Geomagnetic Storms of September 9-14, 2005", Geomagnetism and Aeronomy. Vol. 51, pp. 368-380.
Abstract: This study presents the ionospheric effects caused by the series of geomagnetic storms of September 9–14, 2005. The behavior of different ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill and Arecibo stations during the considered period have been numerically calculated, using a global self-consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP) developed at WD IZMI-RAN. The model calculations of disturbances of the ionospheric parameters during storms qualitatively agree with the experimental data at these midlatitude stations. We suggest that the causes of the quantitative differences between the model calculations and the observational data were the use of the 3-hour Kp index of geomagnetic activity and the dipole approximation of geomagnetic field in GSM TIP, with additional contributions from the effects of solar flares which are not considered in GSM TIP.
BibTeX:
@article{Klimenko2011b,
  author = {M. V. Klimenko and V. V. Klimenko and K. G. Ratovsky and L. P. Goncharenkod},
  title = {Ionospheric Effects Caused by the Series of Geomagnetic Storms of September 9-14, 2005},
  journal = {Geomagnetism and Aeronomy},
  year = {2011},
  volume = {51},
  pages = {368-380},
  url = {http://dx.doi.org/10.1134/S0016793211030108},
  doi = {10.1134/S0016793211030108}
}
Mann I, Pellinen-Wannberg A, Murad E, Popova O, Meyer-Vernet N, Rosenberg M, Mukai T, Czechowski A, Mukai S, Safrankova J and Nemecek Z (2011), "Dusty Plasma Effects in Near Earth Space and Interplanetary Medium", Space Science Reviews. Vol. 161(1-4), pp. 1-47.
Abstract: We review dust and meteoroid fluxes and their dusty plasma effects in the interplanetary medium near Earth orbit and in the Earth’s ionosphere. Aside from in-situ measurements from sounding rockets and spacecraft, experimental data cover radar and optical observations of meteors. Dust plasma interactions in the interplanetary medium are observed by the detection of charged dust particles, by the detection of dust that is accelerated in the solar wind and by the detection of ions and neutrals that are released from the dust. These interactions are not well understood and lack quantitative description. There is still a huge discrepancy in the estimates of meteoroid mass deposition into the atmosphere. The radar meteor observations are of particular interest for determining this number. Dust measurements from spacecraft require a better understanding of the dust impact ionization process, as well as of the dust charging processes. The latter are also important for further studying nanodust trajectories in the solar wind. Moreover understanding of the complex dependencies that cause the variation of nanodust fluxes is still a challenge.
BibTeX:
@article{Mann2011,
  author = {Mann, Ingrid and Pellinen-Wannberg, Asta and Murad, Edmond and Popova, Olga and Meyer-Vernet, Nicole and Rosenberg, Marlene and Mukai, Tadashi and Czechowski, Andrzej and Mukai, Sonoyo and Safrankova, Jana and Nemecek, Zdenek},
  title = {Dusty Plasma Effects in Near Earth Space and Interplanetary Medium},
  journal = {Space Science Reviews},
  year = {2011},
  volume = {161},
  number = {1-4},
  pages = {1-47},
  doi = {10.1007/s11214-011-9762-3}
}
Martinis C, Baumgardner J, Wroten J and Mendillo M (2011), "All-sky imaging observations of conjugate medium-scale traveling ionospheric disturbances in the American sector", Journal of Geophysical Research: Space Physics. Vol. 116(A5), pp. A05326 (7p).
Abstract: All-sky imaging systems at Arecibo, Puerto Rico (18.3°N, 66.7°W, +28° mag. lat.), and Mercedes, Argentina (34.6°S, 59.4°W, ?24.6° mag. lat.), are used to study ionospheric conjugate processes at lower midlatitudes. For the first time in the American sector the simultaneous occurrence in both hemispheres of medium-scale traveling ionospheric disturbances has been observed. The first year of observations yielded 43 nights (?40%) with simultaneous occurrence of airglow bands. Supporting information from GPS receivers indicate the presence of vertical total electron content variations that correlate with the airglow structures observed with the imagers. Weak phase fluctuations have been measured, indicating that these structures do not produce severe large-scale ionospheric irregularities.
BibTeX:
@article{Martinis2011,
  author = {Martinis, C. and Baumgardner, J. and Wroten, J. and Mendillo, M.},
  title = {All-sky imaging observations of conjugate medium-scale traveling ionospheric disturbances in the American sector},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A5},
  pages = {A05326 (7p)},
  doi = {10.1029/2010JA016264}
}
Pavlov AV and Pavlova NM (2011), "Comparison of modeled electron densities and electron and ion temperatures with Arecibo observations during undisturbed and geomagnetic storm periods of 7-11 September 2005", Journal of Geophysical Research: Space Physics. Vol. 116(A3), pp. n/a-n/a.
Abstract: The electron density and the electron and ion temperatures measured by the Arecibo radar at 496 km altitude and NmF2 observed by the Puerto Rico ionosonde are compared with those produced by the model of the ionosphere and plasmasphere to study the time-dependent response of the ionosphere to geomagnetic forcing during the undisturbed and geomagnetic storm periods of 7–11 September 2005. The reasonable agreement between the model results and data requires the modified HWM90 wind and the modified NRLMSISE-00 neutral temperature. The pronounced positive daytime storm changes in NmF2 are created by increases in the upward wind-induced plasma drift due to the neutral wind, while the geomagnetic storm decreases in [N2] and [O2] and the enhanced disturbed upward wind-induced plasma drift cause the pronounced positive nighttime disturbances in NmF2. The storm neutral wind-induced plasma drift and neutral composition changes are responsible for the pronounced negative daytime NmF2 disturbances. The F2 layer transport from lower to higher altitudes by the upward wind-induced plasma drift decreases the distance between the hmF2 and our chosen altitude for study of the topside ionosphere. This results in the increase of the electron density at this chosen altitude due to a more weakly reduction in the electron density with altitude. The pronounced postmidnight peaks observed in the topside electron density over Arecibo are provided by these increases in the electron density
BibTeX:
@article{Pavlov2011,
  author = {Pavlov, A. V. and Pavlova, N. M.},
  title = {Comparison of modeled electron densities and electron and ion temperatures with Arecibo observations during undisturbed and geomagnetic storm periods of 7-11 September 2005},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A3},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010JA016067},
  doi = {10.1029/2010JA016067}
}
Raizada S, Tepley CA, Aponte N and Cabassa E (2011), "Characteristics of neutral calcium and Ca+ near the mesopause, and their relationship with sporadic ion/electron layers at Arecibo", Geophysical Research Letters. Vol. 38(9), pp. n/a-n/a.
Abstract: We present the first simultaneous observations of mesospheric neutral calcium, its ion, and electron density over Arecibo obtained on adjacent nights in December 2009. A good correlation is seen between Sporadic-E and ion layers while the neutrals have different characteristics. The measurements reveal that average abundances in electron densities and ions to be at a maximum on 9 December with values ~4.8 â 109 electrons cm-2 and 3.4 â 107 ions cm-2, while those of the neutrals to be low, of the order of 9.7 â 106 atoms cm-2. The neutral abundance maximizes with values of 1.8 â 107 atoms cm-2 on 10 December, when both ions and electrons display weak layers with abundances almost 3 times lower than on the previous night. A significant correlation between the ions and neutrals indicates that sudden enhancements are caused by advection while a poor correlation is related to chemistry. This study reveals that the ion-neutral coupling is most efficient between 92 and 95 km. Also, the ion-to-neutral ratio is dependent on the strength of the ions or Sporadic-E and can exceed 3.0 during such events. We present evidence of neutralization of the ionized layers occurring on scales of a few tens of minutes for the first time. This agrees fairly well with the lifetimes of Ca+ against neutralization as predicted by recent ion-neutral reactions.
BibTeX:
@article{Raizada2011,
  author = {Raizada, Shikha and Tepley, Craig A. and Aponte, Nestor and Cabassa, Edvier},
  title = {Characteristics of neutral calcium and Ca+ near the mesopause, and their relationship with sporadic ion/electron layers at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2011},
  volume = {38},
  number = {9},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2011GL047327},
  doi = {10.1029/2011GL047327}
}
Santos PT, Brum CGM, Tepley CA, Aponte N, Gonzalez SA and Robles E (2011), "Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 116(A2), pp. A00H13 (9 pages).
Abstract: Thermospheric neutral winds can be the most important driver when modeling ionospheric densities and temperatures. Several papers in this special edition show interesting features of the neutral winds behavior during the last 30 years at the Arecibo Observatory (18.3N, 66.75W; 28.25 dip latitude) using Fabry-Perot Interferometer (FPI) data. A neutral wind vector that changes its direction, becoming more dominantly eastward over the years and a meridional neutral wind component that decreases in magnitude, were found. The main goal of this work is to look for similar evidence of long-term trends in the radar derived winds that might support these recent discoveries and explore the associated ionospheric parameter measurements to look for the effects of these changing winds on the ionosphere. With this purpose in mind, Incoherent Scatter Radar (ISR) measurements of the F region vector drifts are used to derive the corresponding meridional thermospheric neutral wind along the magnetic field over Arecibo during 20 years. Major findings include a decreasing long-term trend (lowering) of the height where the F2- layer peak density occurs (hmF2), which could be related with a more increased downward flux of the ionosphere. A slight decrease in the peak density of the F2- layer (NmF2) after local midnight also was found during the period studied. The meridional wind along the magnetic field derived from ISR data also revealed a long-term trend, becoming more northward during the period studied, with a maximum variation between 02:30UT and 05:30UT.
BibTeX:
@article{Santos2011,
  author = {Santos, P. T. and Brum, C. G. M. and Tepley, C. A. and Aponte, N. and Gonzalez, S. A. and Robles, E.},
  title = {Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A2},
  pages = {A00H13 (9 pages)},
  url = {http://dx.doi.org/10.1029/2011JA016514},
  doi = {10.1029/2011JA016514}
}
Seker I, Fung SF and Mathews JD (2011), "Relation between magnetospheric state parameters and the occurrence of plasma depletion events in the nighttime midlatitude F region", Journal of Geophysical Research: Space Physics. Vol. 116, pp. 4323.
Abstract: Studies using all-sky imagers have revealed the presence of various ionospheric irregularities in the nighttime midlatitude F region. The most prevalent and well known of these are the medium-scale traveling ionospheric disturbances (MSTIDs) that usually occur when the geomagnetic activity is low and midlatitude spread F plumes that are often observed when the geomagnetic activity is high. The inverse and direct relations between geomagnetic activity and the occurrence rate of MSTIDs and midlatitude plumes, respectively, have been observed by several studies using different instruments; however, most of them focus on MSTIDs only and use only Kp to characterize geomagnetic activity. In order to understand the underlying causes of these two relations and to distinguish between MSTIDs and plumes, it is illuminating to better characterize the occurrence of MSTIDs and plumes using multiple magnetospheric state parameters. Here we statistically compare multiple geomagnetic driver and response parameters (such as Kp, AE, Dst, and solar wind parameters) with the occurrence rates of nighttime MSTIDs and plumes observed using an all-sky imager at Arecibo Observatory (AO) between 2003 and 2008. We also present seasonal and annual variations of MSTIDs and plumes at AO. The results not only allow us to better distinguish MSTIDs and plumes, but also to shed further light on the generation mechanism and electrodynamics of these two different phenomena occurring at nighttime in the midlatitude F region.
BibTeX:
@article{Seker2011,
  author = {Seker, I. and Fung, S. F. and Mathews, J. D.},
  title = {Relation between magnetospheric state parameters and the occurrence of plasma depletion events in the nighttime midlatitude F region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  pages = {4323},
  url = {http://dx.doi.org/10.1029/2010JA015521},
  doi = {10.1029/2010JA015521}
}
Tepley CA, Robles E, Garcia R, Santos PT, Brum CM and Burnside RG (2011), "Directional trends in thermospheric neutral winds observed at Arecibo during the past three solar cycles", Journal of Geophysical Research: Space Physics. Vol. 116(A2), pp. A00H06 (9 pages).
Abstract: Since 1980, we have observed the thermospheric neutral wind at the Arecibo Observatory using a Fabry-Perot interferometer to measure the O(1D) 630 nm emission. Burnside and Tepley (1989) examined the first 8 years of this extended data set and found that there were no significant or systematic solar cycle influences on the magnitude or direction of the neutral wind field, nor on its horizontal gradients. Such affects have been observed previously at other locations around the globe, and their absence at Arecibo may have been due to the limited data set. Thus, we have extended the period of acquisition and analysis of our neutral wind measurements to include nearly three complete solar cycles (or approximately 30 years) and will present our results within the framework of the earlier work. While the earlier conclusion that no major systematic solar cycle influence on the neutral winds at Arecibo generally remains intact, we did find a slight increase in wind magnitude and a gradual, yet consistent rotation of the thermospheric neutral wind vector from a general southeast to a more eastward flow during 30 years of observation. We explain the magnitude and directional variations in terms of long-term changes in the density and temperature of the upper atmosphere and their possible dissimilar influences on each wind component that appear as a rotation of the neutral wind vector.
BibTeX:
@article{Tepley2011,
  author = {Tepley, C. A. and Robles, E. and Garcia, R. and Santos, P. T. and Brum, C. M. and Burnside, R. G.},
  title = {Directional trends in thermospheric neutral winds observed at Arecibo during the past three solar cycles},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2011},
  volume = {116},
  number = {A2},
  pages = {A00H06 (9 pages)},
  url = {http://dx.doi.org/10.1029/2010JA016172},
  doi = {10.1029/2010JA016172}
}
Zhou QH, Morton YT, Huang CM, Aponte N, Sulzer M and Gonzalez S (2011), "Incoherent scatter radar observation of E-region vertical electric field at Arecibo", Geophysical Research Letters. Vol. 38(1), pp. n/a-n/a.
Abstract: We report the first spatially and temporally continuous observations of the upward electric field in the E-region using the Arecibo incoherent scatter radar. This is achieved by employing the dual beam incoherent scatter radar measurements of ion velocity and using a theoretical ion-neutral collision model. The derived daytime vertical electric field, from ~105 km to 145 km, shows large height variation, as in previous nighttime rocket measurements. Assuming that the electric field along the field line is negligible, the height variation is the same as the horizontal variation at Arecibo. Although the height variation has been attributed to gravity waves in previous studies, this explanation is not consistent with the temporal characteristics in our observation. We further discuss the error sources that affect the measurement of the electric field.
BibTeX:
@article{Zhou2011a,
  author = {Zhou, Q. H. and Morton, Y. T. and Huang, C. M. and Aponte, N. and Sulzer, M. and Gonzalez, S.},
  title = {Incoherent scatter radar observation of E-region vertical electric field at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2011},
  volume = {38},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010GL045549},
  doi = {10.1029/2010GL045549}
}
Abdu M, Batista I, Brum CGM, MacDougall J, Santos A, de Souza J and Sobral J (2010), "Solar flux effects on the equatorial evening vertical drift and meridional winds over Brazil: A comparison between observational data and the IRI model and the HWM representations", Advances in Space Research . Vol. 46(8), pp. 1078-1085.
Abstract: We present the results of a study of the equatorial evening F region prereversal vertical drift enhancement over Brazil as a function of solar flux (F10.7). The vertical drift is measured from true heights obtained from digisondes operated at an equatorial site, Sao Luis, and at an off equatorial site, Fortaleza. The different magnetic inclinations of the two sites cause different degree of dependence of the vertical drift on magnetic meridional winds permitting an evaluation of the solar flux control on both the evening vertical drift (zonal electric field) and meridional winds. The analysis period covers the year 2001 and 2004 during which the monthly mean F10.7 varied from 245 to 80. The solar flux dependence of the vertical drift of the evening F layer as obtained from the data are compared with the representation of such dependence in the IRI model. While the IRI description of such dependence appears comparable to that is determined from observational data there is significant difference between the drift values in the two cases, the IRI representation being an under-estimation of the observed drift for all flux values. The results are discussed from the perspective of validating the IRI model representations of the vertical drift. The results of the study also shows that the HWM description of the evening thermospheric meridional wind in the Brazilian sector, shows agreement with observation for lower F10.7 values, while it significantly deviates from the observed/calculated meridional wind for higher solar flux values.
BibTeX:
@article{Abdu2010,
  author = {M.A. Abdu and I.S. Batista and C. G. M. Brum and J.W. MacDougall and A.M. Santos and J.R. de Souza and J.H.A. Sobral},
  title = {Solar flux effects on the equatorial evening vertical drift and meridional winds over Brazil: A comparison between observational data and the IRI model and the HWM representations},
  journal = {Advances in Space Research },
  year = {2010},
  volume = {46},
  number = {8},
  pages = {1078-1085},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117710003923},
  doi = {10.1016/j.asr.2010.06.009}
}
Bhatt A (2010), "Exploring The Electron Component In Incoherent Scatter From The Ionosphere". Thesis at: CORNELL UNIVERSITY.
Review: Small thermally-induced ?uctuation in the ionospheric electron density present a scattering cross-section, if probed with a radar frequency higher than the plasma frequency. This technique, known as the incoherent scattering from the ionosphere, is a well-established ?eld of study now. Since the conception of this ?eld of study in 1958, numerous theoretical and experimental efforts have led the way to the high precision ionospheric research we have today. The theory of the incoherent scatter is highly robust. Recent advances in the radar hardware and computing technology have made it possible to probe the ionosphere using the full extent of this theory. In the effort presented here, high spectral resolution incoherent scatter experiments have been used to, for the ?rst time, fully understand the theoretical predictions concerning the electron component of incoherent scatter. The two resonance lines that constitute the electron component are called the gyro line and the plasma line, and are greatly affected by the presence of the earth’s geomagnetic ?eld. The experiments described here present the ?rst unambiguous measurements of the gyro line with high spectral resolution in the incoherent scatter spectrum. Plasma line experiments presented here show the existence of frequency gaps that were predicted in the early days of incoherent scatter theory, but never observed. High latitude plasma line measurements are presented here to show that using the plasma line technique, the gravity waves in the thermosphere can be detected. The intention here is to observe all the components of the incoherent scatter and apply them to understand ionospheric processes.
BibTeX:
@phdthesis{Bhatt2010,
  author = {Bhatt, Asti},
  title = {Exploring The Electron Component In Incoherent Scatter From The Ionosphere},
  school = {CORNELL UNIVERSITY},
  year = {2010},
  url = {http://hdl.handle.net/1813/14795}
}
Chau JL, Aponte NA, Cabassa E, Sulzer MP, Goncharenko LP and Gonzalez SA (2010), "Quiet time ionospheric variability over Arecibo during sudden stratospheric warming events", Journal of Geophysical Research: Space Physics. Vol. 115(A9), pp. n/a-n/a.
Abstract: We present observations of the F-region ionosphere over Arecibo, Puerto Rico (18.34°N, 66.75°W), during the January–February 2008 and January–February 2009 sudden stratospheric warming (SSW) events. For the first period (2008), we have used incoherent scatter radar (ISR) electron density and temperature measurements from the Arecibo Observatory (AO), as well as relative total electron content (TEC) derived from a dual-frequency GPS receiver. For the second event (2009), during which we observed the largest recorded stratospheric warming, we have used the relative GPS TEC. Our analysis indicates that the ionosphere over Arecibo exhibits perturbations after the SSW, the effects are most visible during the daytime. The strongest signatures are observed in the TEC measurements, represented by large enhancements (with respect to non SSW days), particularly during daytime hours. However, the local time dependence of these enhancements is not the same in the two events. In addition, the data show that our results are consistent with the larger than normal daytime vertical drift differences observed at the magnetic equator over Jicamarca. The electron temperature is also affected during the daytime due to changes in electron density, indicating that the electron temperatures is influenced, indirectly, by changes in planetary wave activity in the lower altitudes.
BibTeX:
@article{Chau2010,
  author = {Chau, J. L. and Aponte, N. A. and Cabassa, E. and Sulzer, M. P. and Goncharenko, L. P. and Gonzalez, S. A.},
  title = {Quiet time ionospheric variability over Arecibo during sudden stratospheric warming events},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2010},
  volume = {115},
  number = {A9},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010JA015378},
  doi = {10.1029/2010JA015378}
}
Cohen JA, Pradipta R, Burton LM, Labno A, Lee MC, Watkins BJ, Fallen C, Kuo SP, Burke WJ, Mabius D and See BZ (2010), "Generation of ionospheric ducts by the HAARP HF heater", Physica Scripta. Vol. 2010(T142), pp. 014040.
Abstract: We report an investigation of ionospheric ducts having the shape of large plasma sheets, generated by vertically transmitted HAARP HF heater waves in several experiments conducted in Gakona, Alaska. Theory predicts that O-mode heater wave-created ionospheric ducts form parallel-plate waveguides within the meridional plane, and those generated by the X-mode heater waves are orthogonal to the meridional plane. Our theoretical prediction is supported by measurements of ionosonde data (namely ionograms), range–time–intensity (RTI) plots of UHF and HF backscatter radars, as well as magnetometer data analyses. When these plasma sheets experienced E â B drifts, they were intercepted by the HAARP UHF radar and seen as slanted stripes in the RTI plots. This striking feature was also observed in our earlier experiments using the Arecibo UHF radar.
BibTeX:
@article{Cohen2010,
  author = {J A Cohen and R Pradipta and L M Burton and A Labno and M C Lee and B J Watkins and C Fallen and S P Kuo and W J Burke and D Mabius and B Z See},
  title = {Generation of ionospheric ducts by the HAARP HF heater},
  journal = {Physica Scripta},
  year = {2010},
  volume = {2010},
  number = {T142},
  pages = {014040},
  url = {http://stacks.iop.org/1402-4896/2010/i=T142/a=014040},
  doi = {10.1088/0031-8949/2010/T142/014040}
}
Djuth FT, Zhang LD, Livneh DJ, Seker I, Smith SM, Sulzer MP, Mathews JD and Walterscheid RL (2010), "Arecibo's thermospheric gravity waves and the case for an ocean source", Journal of Geophysical Research: Space Physics. Vol. 115(A8), pp. n/a-n/a.
Abstract: Wave-like disturbances in electron density ne have been observed in the thermosphere above Arecibo Observatory, Puerto Rico throughout its 45 year history. However, only recently has it become evident that these waves are continuously present in the Arecibo thermosphere. The wave characteristics are fairly constant between day and night and from season to season. High-resolution electron density measurements obtained by applying the coded long-pulse radar technique to photoelectron-enhanced Langmuir waves are presented. These new observations strongly suggest that the perturbations in electron density are the result of internal acoustic-gravity waves (AGWs) propagating through the Arecibo thermosphere. The AGWs appear to be broadbanded in wave number space. The downward phase trajectories of Dne/ne between 400 and 120 km combined with the low horizontal phase velocities obtained from airglow measurements support the idea that the AGWs are not ducted but rather are locally produced. In addition, the altitudes at which major peaks in Dne/ne are observed follow theoretical estimates for nonducted waves. The nominal period of the AGWs is ?60 min at 250 km altitude, but periods of ~20 min are also evident at lower attitudes. Classic sources of AGWs do not appear to be consistent with the Arecibo observations of a continuous flux of background AGWs. Ray tracing of the AGWs combined with 630.0 nm airglow observations point to a source location in the Atlantic Ocean that is roughly 2100 km east northeast of Arecibo. Internal ocean waves generated in response to the internal tide at the mid-Atlantic Ridge are the most likely source of Arecibo's thermospheric AGWs.
BibTeX:
@article{Djuth2010,
  author = {Djuth, F. T. and Zhang, L. D. and Livneh, D. J. and Seker, I. and Smith, S. M. and Sulzer, M. P. and Mathews, J. D. and Walterscheid, R. L.},
  title = {Arecibo's thermospheric gravity waves and the case for an ocean source},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2010},
  volume = {115},
  number = {A8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009JA014799},
  doi = {10.1029/2009JA014799}
}
Erickson P, Goncharenko L, Nicolls M, Ruohoniemi M and Kelley M (2010), "Dynamics of North American sector ionospheric and thermospheric response during the November 2004 superstorm", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 72(4), pp. 292-301.
Abstract: We present a study of ionospheric and thermospheric response during a November 9–10, 2004 major geomagnetic storm event (DsT ??300 nT). We utilize the North American sector longitude chain of incoherent scatter radars at Arecibo, Millstone Hill, and Sondrestrom, operating as part of a coordinated international mesosphere/lower thermosphere coupling study experiment. Total electron content (TEC) determinations from global positioning system (GPS) ground receivers, ground magnetometer traces from the Canadian CANOPUS array, Defense Meteorological Satellite Platform (DMSP) topside data, and global convection patterns from the SuperDARN radar network are analyzed to place the detailed radar data in proper mesoscale context. The plasmaspheric boundary layer (PBL) expanded greatly in the dusk sector during ring current intensification to span more than 25° of magnetic latitude, reaching as far south as 30° invariant latitude. Strong sub-auroral polarization stream velocities of more than 1 km/s were accompanied by large upwards thermal O+ fluxes to the overlying magnetosphere. The large PBL expansion subsequently exposed both Millstone Hill and Sondrestrom to the auroral convection pattern, which developed a complex multicell and reverse convection response under strongly northward IMF conditions during a period of global interplanetary electric field penetration. Large traveling atmospheric and ionospheric disturbances caused significant neutral wind and ion velocity surges in the mid-latitude and tropical ionosphere and thermosphere, with substorm activity launching equatorward neutral wind enhancements and subsequent mid-latitude dynamo responses at Millstone Hill. However, ionosphere and thermosphere observations at Arecibo point to significant disturbance propagation modification in the post-dusk sector PBL region.
BibTeX:
@article{Erickson2010,
  author = {P.J. Erickson and L.P. Goncharenko and M.J. Nicolls and M. Ruohoniemi and M.C. Kelley},
  title = {Dynamics of North American sector ionospheric and thermospheric response during the November 2004 superstorm},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2010},
  volume = {72},
  number = {4},
  pages = {292-301},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682609000881},
  doi = {10.1016/j.jastp.2009.04.001}
}
Kelley MC and Peria WJ (2010), "Interaction of a high-power UHF beam with the ionosphere", Radio Science. Vol. 45(1), pp. n/a-n/a.
Abstract: In 1992 a rocket was launched into a high-power radio beam to study its interaction with the ionosphere. The frequency of the beam, 5.1 MHz, was optimized for such interactions since the frequency used was below the maximum plasma frequency and hence was reflected in a manner that optimized such an interaction. Fortuitously, the rocket passed quite close to the diagnostic Arecibo UHF (430 MHz) radar beam and remarkably, as reported here, we find that there was an interaction as well with the UHF beam. In retrospect, however, we see that the energy density of the UHF radar was more than an order of magnitude higher than the plasma energy density. And, although the quiver velocity of the electrons in the beam is only 4% of their thermal speed, the ponderomotive force is quite a bit larger than the other forces in the medium. This force creates a drift velocity perpendicular to the magnetic field at the beam edge which, we show, is unstable to the drift wave instability and is likely to create the heated ions and fluctuating electric field and plasma density we observe. These results suggest that any transmission of high-power radio waves from a solar power satellite to the ground will interact with the ionosphere in a manner that must be studied before such an expensive project is initiated.
BibTeX:
@article{Kelley2010,
  author = {Kelley, M. C. and Peria, W. J.},
  title = {Interaction of a high-power UHF beam with the ionosphere},
  journal = {Radio Science},
  year = {2010},
  volume = {45},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009RS004160},
  doi = {10.1029/2009RS004160}
}
Kelley MC, Ilma RR, Nicolls M, Erickson P, Goncharenko L, Chau JL, Aponte N and Kozyra JU (2010), "Spectacular low- and mid-latitude electrical fields and neutral winds during a superstorm", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 72(4), pp. 285-291.
Abstract: In November 2004, a major magnetic storm occurred, a lengthy portion of which was recorded by the Upper Atmospheric Radar Chain. On the 9th and 10th, the Jicamarca Radar detected the highest magnitude penetrating electric fields (+-3 mV/m) and vertical drifts (±120 m/s) ever seen at this premiere facility. These large and variable drifts were highly correlated with the interplanetary magnetic and electric fields and created a double F layer on the dayside and unusual TEC behavior throughout the low-latitude zone. These solar wind-induced drifts both suppressed and generated irregularities at the magnetic equator at different times. Large-scale thermospheric disturbances were generated by high-latitude heating and tracked through the middle- to low-latitude zones where both parallel and perpendicular plasma drifts created major ionospheric changes. The auroral oval was located at a magnetic L shell of about three for many hours.
BibTeX:
@article{Kelley2010a,
  author = {Michael C. Kelley and Ronald R. Ilma and Michael Nicolls and Philip Erickson and Larisa Goncharenko and Jorge L. Chau and Nestor Aponte and Janet U. Kozyra},
  title = {Spectacular low- and mid-latitude electrical fields and neutral winds during a superstorm},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2010},
  volume = {72},
  number = {4},
  pages = {285-291},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682608003866},
  doi = {10.1016/j.jastp.2008.12.006}
}
Komjathy A, Wilson B, Pi X, Akopian V, Dumett M, Iijima B, Verkhoglyadova O and Mannucci AJ (2010), "JPL/USC GAIM: On the impact of using COSMIC and ground-based GPS measurements to estimate ionospheric parameters", Journal of Geophysical Research: Space Physics. Vol. 115(A2), pp. n/a-n/a.
Abstract: The University of Southern California (USC) and the Jet Propulsion Laboratory (JPL) have jointly developed the Global Assimilative Ionospheric Model (GAIM) to monitor space weather, study storm effects, and provide ionospheric calibration for space weather applications. JPL/USC GAIM is a physics-based 3-D data assimilation model that uses both four-dimensional variational analysis and Kalman-filter techniques to solve for the ion and electron density state and key drivers such as equatorial electrodynamics, neutral winds, and production terms. Here we report on GAIM Kalman filter-based assimilation results using ground-based GPS and COSMIC-derived total electron count (TEC) measurements. We find that assimilating COSMIC measurements into GAIM improves critical ionospheric parameters such as NmF2 and HmF2. Assimilating COSMIC data produces higher-accuracy vertical electron density profile “shapes,” as verified by comparisons to independent electron density profiles measured at Arecibo, Jicamarca, and Millstone Hill incoherent scatter radar (ISR). We also find significant improvement in global vertical TEC (VTEC) maps when assimilating COSMIC measurements, verified by comparing GAIM output with VTEC measurements from the Jason ocean altimeter. For 3 days in June 2006, improvement in accuracy compared to ground-data-only assimilation is found to be 30%, 28%, and 44%, respectively.
BibTeX:
@article{Komjathy2010,
  author = {Komjathy, Attila and Wilson, Brian and Pi, Xiaoqing and Akopian, Vardan and Dumett, Miguel and Iijima, Byron and Verkhoglyadova, Olga and Mannucci, Anthony J.},
  title = {JPL/USC GAIM: On the impact of using COSMIC and ground-based GPS measurements to estimate ionospheric parameters},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2010},
  volume = {115},
  number = {A2},
  pages = {n/a-n/a},
  doi = {10.1029/2009JA014420}
}
Martinis C, Baumgardner J, Wroten J and Mendillo M (2010), "Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo", Geophysical Research Letters. Vol. 37, pp. L11103.
Abstract: All-sky imaging data of 630.0 nm airglow emissions are used to study the seasonal and solar activity dependence of medium-scale traveling ionospheric disturbances (MSTIDs) over Arecibo, Puerto Rico (18.3° N, 66.7° W, 28° N mag lat). MSTIDs are typical F-region signatures at midlatitudes, yet limited statistical results in the American sector hindered the progress in our understanding of these dynamical structures. This study compiles data from 2002 to 2007 and shows for the first time that optically-determined MSTIDs at Arecibo present a semiannual pattern with peak occurrence at both solstices. In the Japanese longitude sector, a similar pattern has been found, but one with a main peak during local summer. This paper explains the high occurrence rate during local winter at Arecibo via E-layer/F-layer coupling and inter-hemispheric coupling, thus accounting for a consistent morphology between the two longitude sectors.
BibTeX:
@article{Martinis2010,
  author = {Martinis, C. and Baumgardner, J. and Wroten,J. and Mendillo, M.},
  title = {Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2010},
  volume = {37},
  pages = {L11103},
  url = {http://dx.doi.org/10.1029/2010GL043569},
  doi = {10.1029/2010GL043569}
}
Mathews JD, Briczinski SJ, Malhotra A and Cross J (2010), "Extensive meteoroid fragmentation in V/UHF radar meteor observations at Arecibo Observatory", Geophysical Research Letters. Vol. 37(4), pp. n/a-n/a.
Abstract: New 46.8/430 MHz (V/UHF) radar meteor observations at Arecibo Observatory reveal many previously unreported features in the radar meteor return that are consistent with meteoroid fragmentation. These signature features—observed at both V/UHF—include strong intra-pulse and pulse-to-pulse fading as the result of interference between or among multiple meteor head-echo returns and between head-echo and impulsive “flare” event “trail-echoes”. A few events are suggestive of differential ablation. These V/UHF radar observations are particularly useful as coaxial beams enable common volume observations that remove much ambiguity in the interpretation of the observations in terms of meteoroid fragmentation. These results, combined with simple modeling and two 500 sample statistical studies, lead us to conclude that a majority of the ~17,000 AO radar meteor events included in this study exhibit fragmentation—manifested as non-uniform lightcurves—implying that the form of meteoroid mass flux into the upper atmosphere goes well beyond simple ablation.
BibTeX:
@article{Mathews2010,
  author = {Mathews, J. D. and Briczinski, S. J. and Malhotra, A. and Cross, J.},
  title = {Extensive meteoroid fragmentation in V/UHF radar meteor observations at Arecibo Observatory},
  journal = {Geophysical Research Letters},
  year = {2010},
  volume = {37},
  number = {4},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009GL041967},
  doi = {10.1029/2009GL041967}
}
Matteo NA and Morton YT (2010), "Higher-order ionospheric error at Arecibo, Millstone, and Jicamarca", Radio Science. Vol. 45(6), pp. n/a-n/a.
Abstract: The ionosphere is a dominant source of Global Positioning System receiver range measurement error. Although dual-frequency receivers can eliminate the first-order ionospheric error, most second- and third-order errors remain in the range measurements. Higher-order ionospheric error is a function of both electron density distribution and the magnetic field vector along the GPS signal propagation path. This paper expands previous efforts by combining incoherent scatter radar (ISR) electron density measurements, the International Reference Ionosphere model, exponential decay extensions of electron densities, the International Geomagnetic Reference Field, and total electron content maps to compute higher-order error at ISRs in Arecibo, Puerto Rico; Jicamarca, Peru; and Millstone Hill, Massachusetts. Diurnal patterns, dependency on signal direction, seasonal variation, and geomagnetic activity dependency are analyzed. Higher-order error is largest at Arecibo with code phase maxima circa 7 cm for low-elevation southern signals. The maximum variation of the error over all angles of arrival is circa 8 cm.
BibTeX:
@article{Matteo2010,
  author = {Matteo, N. A. and Morton, Y. T.},
  title = {Higher-order ionospheric error at Arecibo, Millstone, and Jicamarca},
  journal = {Radio Science},
  year = {2010},
  volume = {45},
  number = {6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2010RS004394},
  doi = {10.1029/2010RS004394}
}
Ratovsky K, Shpynev B, Oinats A and Medvedev A (2010), "An analysis of the topside ionosphere parameters based on the long-duration Irkutsk incoherent scatter radar measurements", Advances in Space Research. Vol. 46(8), pp. 984-989.
Abstract: The topside ionosphere parameters are studied based on the long-duration Irkutsk incoherent scatter radar (52.9N, 103.3E) measurements conducted in September 2005, June and December 2007. As a topside ionosphere parameter we chose the vertical scale height (VSH) related to the gradient of the electron density logarithm above the peak height. For morphological studies we used median electron density profiles. Besides the median behavior we also studied VSH disturbances (deviations from median values) during the magnetic storm of September 11th 2005. We compared the Irkutsk incoherent scatter radar data with the Millstone Hill and Arecibo incoherent scatter radar observations, the IRI-2007 prediction (using the two topside options) and VSH derived from the Irkutsk DPS-4 Digisonde bottomside measurements.
BibTeX:
@article{Ratovsky2010,
  author = {K.G. Ratovsky and B.G. Shpynev and A.V. Oinats and A.V. Medvedev},
  title = {An analysis of the topside ionosphere parameters based on the long-duration Irkutsk incoherent scatter radar measurements},
  journal = {Advances in Space Research},
  year = {2010},
  volume = {46},
  number = {8},
  pages = {984-989},
  doi = {10.1016/j.asr.2010.06.006}
}
Rother M, Schlegel K, Luhr H and Cooke D (2010), "Validation of CHAMP electron temperature measurements by incoherent scatter radar data", Radio Science. Vol. 45(6), pp. n/a-n/a.
Abstract: The CHAMP performed electron temperature, Te, measurements during its mission period from 2000 to 2010. For the validation of these Te data comparisons with incoherent scatter radar observations at Arecibo and TromsÜ (EISCAT) have been performed. Data from 94 (143) close encounters of the satellite with the Arecibo (TromsÜ) radar are available for the validation. Results at TromsÜ were reasonable, but at Arecibo significant differences, in particular for low temperature, were observed. Investigations showed that CHAMP Te measurements have a bias which switches sign between northbound and southbound orbit arcs. The global distribution of the bias shows systematic latitudinal structures antisymmetric to the magnetic equator. After correction of this effect, CHAMP Te data show a good agreement with the radar observations at both sites. From the mean relative deviation we deduce that CHAMP Te data are low by 3% with a standard deviation of 8%. Validated CHAMP Te data are available for the period 20 February 2002 through 20 February 2010.
BibTeX:
@article{Rother2010,
  author = {Rother, M. and Schlegel, K. and Luhr, H. and Cooke, D.},
  title = {Validation of CHAMP electron temperature measurements by incoherent scatter radar data},
  journal = {Radio Science},
  year = {2010},
  volume = {45},
  number = {6},
  pages = {n/a-n/a},
  doi = {10.1029/2010RS004445}
}
Souza J, Brum CGM, Abdu M, Batista I, Jr. WA, Bailey G and Bittencourt J (2010), "Parameterized Regional Ionospheric Model and a comparison of its results with experimental data and IRI representations ", Advances in Space Research . Vol. 46(8), pp. 1032-1038.
Abstract: We describe a Parameterized Regional Ionospheric Model (PARIM) to calculate the spatial and temporal variations of the ionospheric electron density/plasma frequency over the Brazilian sector. The ionospheric plasma frequency values as calculated from an enhanced Sheffield University Plasmasphere–Ionosphere Model (SUPIM) were used to construct the model. PARIM is a time-independent 3D regional model (altitude, longitude/local time, latitude) used to reproduce SUPIM plasma frequencies for geomagnetic quiet condition, for any day of the year and for low to moderately high solar activity. The procedure to obtain the modeled representation uses finite Fourier series so that all plasma frequency dependencies can be represented by Fourier coefficients. PARIM presents very good results, except for the F region peak height (hmF2) near the geomagnetic equator during times of occurrence of the F3 layer. The plasma frequency calculated by IRI from E region to bottomside of the F region present latitudinal discontinuities during morning and evening times for both solar minimum and solar maximum conditions. Both the results of PARIM and the IRI for the E region peak density show excellent agreement with the observational values obtained during the conjugate point equatorial experiment (COPEX) campaign. The IRI representations significantly underestimate the foF2 and hmF2 compared to the observational results over the COPEX sites, mainly during the evening-nighttime period.
BibTeX:
@article{Souza2010,
  author = {J.R. Souza and C. G. M. Brum and M.A. Abdu and I.S. Batista and W.D. Asevedo Jr. and G.J. Bailey and J.A. Bittencourt},
  title = {Parameterized Regional Ionospheric Model and a comparison of its results with experimental data and IRI representations },
  journal = {Advances in Space Research },
  year = {2010},
  volume = {46},
  number = {8},
  pages = {1032-1038},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117710003911},
  doi = {10.1016/j.asr.2009.11.025}
}
Abdu MA and Brum CGM (2009), "Electrodynamics of the vertical coupling processes in the atmosphere-ionosphere system of the low latitude region", Earth Planets and Space. Vol. 61, pp. 385-395.
Abstract: Dynamical, electro-dynamical and electrical coupling processes originating from upward propagation of atmospheric waves, and magnetosphere-ionosphere interaction are responsible for the large degree of variabilities observed in the low latitude ionosphere. One of the most outstanding aspects of its phenomenology is related to the sunset electrodynamical processes responsible for the evening enhancements in zonal and vertical electric fields and the associated spread of F/plasma bubble irregularity development. Recent observational results have provided evidence of significant contribution to their quiet time variability arising from thermospheric wind patterns, upward propagating planetary waves and possibly sporadic E layers. This paper provides an overview and some new results on planetary wave coupling with the equatorial F region, the E layer conductivity as key connecting mechanism, a possibly interactive role by sporadic E layers, and the resulting day-to-day variability in the evening prereversal electric field enhancements with consequences on spread F development.
BibTeX:
@article{Abdu2009,
  author = {M. A. Abdu and C. G. M. Brum},
  title = {Electrodynamics of the vertical coupling processes in the atmosphere-ionosphere system of the low latitude region},
  journal = {Earth Planets and Space},
  year = {2009},
  volume = {61},
  pages = {385-395},
  note = {Arecibo author},
  url = {http://adsabs.harvard.edu/abs/2009EP%26S...61..385A}
}
Briczinski SJ, Mathews JD and Meisel DD (2009), "Statistical and fragmentation properties of the micrometeoroid flux observed at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 114(A4), pp. n/a-n/a.
Abstract: The micrometeor observations performed using the 430 MHz Arecibo Observatory radar have proven to be crucial for the understanding of meteoric effects on the aeronomy of the upper atmosphere. Meteors observed during the February 2001, 2006, and 2007 campaigns have been analyzed with a fast Fourier transform periodic search algorithm that automatically and uniformly detects meteor events between altitudes of 80 and 142 km. We present a description of the new technique used to detect meteors as well as the meteoroid parameters: altitude profiles, radial speeds, and decelerations. We also note the expected correlation between the radar transmitted power and the observed meteor event rate. The large number of events has enabled us to statistically estimate the average mass density of the observed population indicating that our detected events are generally cometary (1 g/cm3) and not asteroidal (3 g/cm3) in origin. Additionally, many meteor events are observed in which the radar meteor disappears from one radar pulse to the next (i.e., in 1 ms). We interpret this as indicative of the catastrophic destruction of the meteoroid. Until destruction, these events appear to undergo only minor ablation of their volatile components over the observed trajectory. As with a major fraction of all events recorded, the meteoroids that disappear in a terminal event show linear decelerations before their abrupt disappearance. This apparently low ablative mass deposition process may play an important role in the composition (aeronomy) of the upper atmosphere, as it likely produces submicron-sized particles rather than the atom level products of ablation. First results on the altitude, speed, and mass distributions of terminal event meteoroids are given yielding some clues on the physics of the terminal event. Finally, the statistics of those events that yield no deceleration are compared statistically with those that exhibit deceleration with the conclusion that both groups are statistically the same. We further conclude that along with low signal-to-noise ratio and short echo duration, fragmentation of this group of particles is a primary cause of the inability to determine deceleration.
BibTeX:
@article{Briczinski2009,
  author = {Briczinski, S. J. and Mathews, J. D. and Meisel, D. D.},
  title = {Statistical and fragmentation properties of the micrometeoroid flux observed at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2009},
  volume = {114},
  number = {A4},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009JA014054},
  doi = {10.1029/2009JA014054}
}
Christakis N, Haldoupis C, Zhou Q and Meek C (2009), "Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo", Annales Geophysicae. Vol. 27, pp. 923-931.
Abstract: Sporadic E layers (Es) follow regular daily patterns in variability and altitude descent, which are determined primarily by the vertical tidal wind shears in the lower thermosphere. In the present study a large set of sporadic E layer incoherent scatter radar (ISR) measurements are analyzed. These were made at Arecibo (Geog. Lat. ~18° N; Magnetic Dip ~50°) over many years with ISR runs lasting from several hours to several days, covering evenly all seasons. A new methodology is applied, in which both weak and strong layers are clearly traced by using the vertical electron density gradient as a function of altitude and time. Taking a time base equal to the 24-h local day, statistics were obtained on the seasonal behavior of the diurnal and semidiurnal tidal variability and altitude descent patterns of sporadic E at Arecibo. The diurnal tide, most likely the S(1,1) tide with a vertical wavelength around 25 km, controls fully the formation and descent of the metallic Es layers at low altitudes below 110 km. At higher altitudes, there are two prevailing layers formed presumably by vertical wind shears associated mainly with semidiurnal tides. These include: 1) a daytime layer starting at ~130 km around midday and descending down to 105 km by local midnight, and 2) a less frequent and weaker nighttime layer which starts prior to midnight at ~130 km, descending downwards at somewhat faster rate to reach 110 km by sunrise. The diurnal and semidiurnal-like pattern prevails, with some differences, in all seasons. The differences in occurrence, strength and descending speeds between the daytime and nighttime upper layers are not well understood from the present data alone and require further study.
BibTeX:
@article{Christakis2009,
  author = {Christakis, N and Haldoupis, C and Zhou, Q and Meek, C},
  title = {Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo},
  journal = {Annales Geophysicae},
  year = {2009},
  volume = {27},
  pages = {923-931},
  url = {www.ann-geophys.net/27/923/2009/},
  doi = {10.5194/angeo-27-923-2009}
}
Fentzke J, Janches D and Sparks J (2009), "Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 71, pp. 653-661.
Abstract: In this work, we use a semi-empirical model of the micrometeor input function (MIF) together with meteor head-echo observations obtained with two high power and large aperture (HPLA) radars, the 430 MHz Arecibo Observatory (AO) radar in Puerto Rico (18°N, 67°W) and the 450 MHz Poker flat incoherent scatter radar (PFISR) in Alaska (65°N, 147°W), to study the seasonal and geographical dependence of the meteoric flux in the upper atmosphere. The model, recently developed by Janches et al. [2006a. Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars. Journal of Geophysical Research 111] and Fentzke and Janches [2008. A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function observed at arecibo. Journal of Geophysical Research (Space Physics) 113 (A03304)], includes an initial mass flux that is provided by the six known meteor sources (i.e. orbital families of dust) as well as detailed modeling of meteoroid atmospheric entry and ablation physics. In addition, we use a simple ionization model to treat radar sensitivity issues by defining minimum electron volume density production thresholds required in the meteor head-echo plasma for detection. This simplified approach works well because we use observations from two radars with similar frequencies, but different sensitivities and locations. This methodology allows us to explore the initial input of particles and how it manifests in different parts of the MLT as observed by these instruments without the need to invoke more sophisticated plasma models, which are under current development. The comparisons between model predictions and radar observations show excellent agreement between diurnal, seasonal, and latitudinal variability of the detected meteor rate and radial velocity distributions, allowing us to understand how individual meteoroid populations contribute to the overall flux at a particular location and season.
BibTeX:
@article{Fentzke2009,
  author = {J.T. Fentzke and D. Janches and J.J. Sparks},
  title = {Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2009},
  volume = {71},
  pages = {653-661},
  doi = {10.1016/j.jastp.2008.07.015}
}
Fentzke J, Janches D, Strelnikova I and Rapp M (2009), "Meteoric smoke particle properties derived using dual-beam Arecibo UHF observations of D-region spectra during different seasons", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 71(17-18), pp. 1982-1991.
Abstract: We present a seasonal study of the presence and characteristics of meteoric smoke particles (MSPs) in the D-region plasma derived from observations using the Gregorian and line feeds of the 430 MHz dual-beam Arecibo Observatory (AO) incoherent scatter radar (ISR) in Puerto Rico (18?N,67?W)(18?N,67?W). MSPs are the product of re-condensation of ablated meteoric material and are believed to be the condensation nuclei for the formation of ice particles in the polar mesopause region. These CNs can then be responsible for the formation of polar mesospheric clouds (PMCs), noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSEs). For this work, we simultaneously employed both AO antenna feeds to define two radar beams inclined 15?15? east and west of zenith (Janches et al., 2006). Because of the non-vertical pointing, the sampled spectra are Doppler shifted due to the rapidly changing neutral dynamics of the MLT region. We correct this effect by removing the Doppler shift using the radial velocities estimated every ?2?2 min and then integrate the corrected spectra for longer periods to enhance signal-to-noise ratio (SNR) and better investigate the variability of MSP properties. We determine MSP radii and number densities utilizing a method similar to the one developed by Strelnikova et al. (2007) in which the autocorrelation function (ACF) is approximated as the sum of two exponential decays, i.e., the power spectrum is approximated as the sum of two Lorentzians. This method, which assumes mono-disperse particles, allows us to determine mean particle properties in the 80–95 km altitude range during the hours of 10–14 AO LT when the detected SNR from the D-region is highest. Results from this work show MSP radii approximately 0.6–1.5 nm is size depending on altitude and season. Also, MSP densities as a function of altitude and season are determined with the aid of the IRI model resulting in values on the order of 102–104102–104 per cubic centimeter. Our error analysis shows that spectral broadening from atmospheric sources such as neutral turbulence induced by gravity wave vertical variance, and non-zero vertical winds results in <10%<10% change in derived MSP radii. Also, since our dataset covers different seasons, we investigate a potential correlation between the seasonal variations of the derived MSPs properties with that of the meteoric input function (MIF) in the MLT above Arecibo.
BibTeX:
@article{Fentzke2009a,
  author = {J.T. Fentzke and D. Janches and I. Strelnikova and M. Rapp},
  title = {Meteoric smoke particle properties derived using dual-beam Arecibo UHF observations of D-region spectra during different seasons},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2009},
  volume = {71},
  number = {17-18},
  pages = {1982-1991},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682609002326},
  doi = {10.1016/j.jastp.2009.09.002}
}
Friedman JS, Zhang X, Chu X and Forbes JM (2009), "Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space", Journal of Geophysical Research: Atmospheres. Vol. 114(D11), pp. n/a-n/a.
Abstract: We present an analysis of longitudinal variation in the solar semidiurnal tide observed in the nocturnal thermal structure of the low-latitude mesopause region (83–103 km), with a focus on two sites: Arecibo, Puerto Rico (18.3°N, 66.8°W) and Maui, Hawaii (20.7°N, 156.3°W). Localized observations made by lidars are combined with longitudinal measurements by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and compared with the Global-Scale Wave Model-2002 (GSWM-02) for 6 months: January, April, May, July, August, and October. In winter-spring, lidar-measured amplitudes are larger than those recorded by SABER, whereas in summer the amplitudes are similar and in autumn the lidars observe smaller amplitudes than SABER. GSWM amplitudes are between the lidar and SABER measurements for January, are comparable to the measurements in spring, underpredict for summer, and agree with the lidars in autumn. The phase structure is consistent among lidars and SABER for all of the months except January, when there is a large phase shift, and the local time of the temperature maximum is different between Arecibo and Maui. GSWM shows better agreement with phase measurements in winter-spring than in summer-autumn. Modal analysis of the SABER data indicates that the (2, 2) Hough mode is present throughout the year. In winter, it is joined by the (2, 4) mode, while in summer it is accompanied by the (2, 3) mode. This change in the predominant Hough modes may be related to the winter-summer phase difference.
BibTeX:
@article{Friedman2009,
  author = {Friedman, Jonathan S. and Zhang, Xiaoli and Chu, Xinzhao and Forbes, Jeffrey M.},
  title = {Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2009},
  volume = {114},
  number = {D11},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009JD011763},
  doi = {10.1029/2009JD011763}
}
Hysell DL, Nossa E, Larsen MF, Munro J, Sulzer MP and Gonzalez SA (2009), "Sporadic E layer observations over Arecibo using coherent and incoherent scatter radar: Assessing dynamic stability in the lower thermosphere", Journal of Geophysical Research: Space Physics. Vol. 114(A12), pp. n/a-n/a.
Abstract: A patchy sporadic E ionization layer was observed using the 430 MHz incoherent scatter radar at the Arecibo Radio Observatory and a new, 30 MHz coherent scatter radar imager located on St. Croix. The former measured state parameters of the layer (plasma density, temperature, and composition) while the latter observed small-scale plasma waves and the associated quasiperiodic (QP) echoes. Regularization was used to estimate horizontal vector ion drifts from Arecibo line-of-sight data. Assuming the ion temperatures and drifts to be representative of the neutral atmospheric temperatures and drifts in the mesosphere lower-thermosphere (MLT) region, we evaluated the Richardson number criterion for neutral dynamic instability in regions occupied by the layers. We find that the condition for instability was generally satisfied and thus that dynamic instability is consistent with the layer breakup. The electrodynamics of the resulting patchy layers could then give rise to the QP echoes.
BibTeX:
@article{Hysell2009,
  author = {Hysell, D. L. and Nossa, E. and Larsen, M. F. and Munro, J. and Sulzer, M. P. and Gonzalez, S. A.},
  title = {Sporadic E layer observations over Arecibo using coherent and incoherent scatter radar: Assessing dynamic stability in the lower thermosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2009},
  volume = {114},
  number = {A12},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009JA014403},
  doi = {10.1029/2009JA014403}
}
Janches D, Fritts D, Nicolls M and Heinselman C (2009), "Observations of D-region structure and atmospheric tides with PFISR during active aurora", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 71(6-7), pp. 688-696.
Abstract: We report on combined spectral measurements of the D-region ionosphere and the polar summer mesosphere and lower thermosphere performed on 9 June 2007 with the 450 MHz Poker Flat Incoherent Scatter Radar (PFISR) under active auroral conditions. Observations during the first 7 h occurred at nighttime and revealed strong temporal correlations between enhanced auroral precipitation, the occurrence of polar mesosphere summer echoes (PMSE), and enhanced electron densities (Ne) extending to much lower altitudes (~60-80km) than the previously reported at these latitudes without the presence of a polar cap absorption (PCA) event. PMSE and lower D-region echoes most often occurred together and PMSE were more often visible to PFISR before the Ne of the D-region was sufficiently high to be detected. These measurements also enabled definition of high precision horizontal winds (errors of 2–3ms-1) in the ~64–90km altitude range, which has previously been possible only with MF and HF radars, with the Arecibo 430 MHz IS radar (ISR), or with other ISRs during PCA events. This observing technique allowed for ~24h of almost continuous measurements of the meridional and zonal wind fields and thus permitted the measurements of atmospheric tides over this large altitude range. We determine amplitude and phase for both the diurnal and semi-diurnal tides showing the latter to be stronger as expected at these latitudes. We also present observations of a gravity wave during a quiet period indicating that PFISRs sensitivity is sufficiently high to obtain reliable spectral information even when electron densities are not enhanced by aurora or a PCA event and are as low as 109e-/m3. These results show the capabilities of PFISR to study the neutral dynamics in the polar D-region and mesosphere and lower thermosphere (MLT) over an unprecedented altitude range.
BibTeX:
@article{Janches2009,
  author = {D. Janches and D.C. Fritts and M.J. Nicolls and C.J. Heinselman},
  title = {Observations of D-region structure and atmospheric tides with PFISR during active aurora},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2009},
  volume = {71},
  number = {6-7},
  pages = {688-696},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682608002216},
  doi = {10.1016/j.jastp.2008.08.015}
}
Kelley MC, Wong VK, Aponte N, Coker C, Mannucci AJ and Komjathy A (2009), "Comparison of COSMIC occultation-based electron density profiles and TIP observations with Arecibo incoherent scatter radar data", Radio Science. Vol. 44(4), pp. n/a-n/a.
Abstract: In June 2006 an early opportunity arose to compare occultation-based electron density profiles with incoherent scatter radar data. The former were made available by the constellation of satellites called COSMIC. We find that the value of the peak plasma density in the F region is reasonably well characterized but that the altitude of the peak is overestimated above about 300 km and underestimated below that height. A simple Abel transform is not suitable for determining the E region profiles, even in daytime. We also compared the emission strength recorded by the Tiny Ionospheric Photometer (TIP) on board COSMIC to the Arecibo measurement of the TEC as part of an ongoing effort to calibrate the former. The TIP and Arecibo data both show the development of an ionospheric storm of the type referred to as high-intensity, long-duration continuous AE activity. It is surprising that such a modest magnetic storm (Dst ~-2.5 nT) resulted in the anomaly moving to nearly 30° magnetic latitude.
BibTeX:
@article{Kelley2009,
  author = {Kelley, M. C. and Wong, V. K. and Aponte, Nestor and Coker, Clayton and Mannucci, A. J. and Komjathy, A.},
  title = {Comparison of COSMIC occultation-based electron density profiles and TIP observations with Arecibo incoherent scatter radar data},
  journal = {Radio Science},
  year = {2009},
  volume = {44},
  number = {4},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008RS004087},
  doi = {10.1029/2008RS004087}
}
Kelley MC, Ilma RR and Crowley G (2009), "On the origin of pre-reversal enhancement of the zonal equatorial electric field", Annales Geophysicae. Vol. 27, pp. 2053-2056.
Abstract: In November 2004, a large and variable interplanetary electric field (IEF) was felt in the reference frame of the Earth. This electric field penetrated to the magnetic equator and, when the Jicamarca Radio Observatory (JRO) was in the dusk sector, resulted in a reversal of the normal zonal component of the field. In turn, this caused a counter-electrojet (CEJ), a westward current rather than the usual eastward current. At the time of the normal pre-reversal enhancement (PRE) of the eastward field, the Jicamarca incoherent scatter radar (ISR) observed that the westward component became even more westward. Two of the three current explanations for the PRE depend on the neutral wind patterns. However, this unique event was such that the neutral wind-driven dynamos could not have changed. The implication is that the Haerendel-Eccles mechanism, which involves partial closure of the equatorial electrojet (EEJ) after sunset, must be the dominant mechanism for the PRE.
BibTeX:
@article{Kelley2009a,
  author = {Kelley, M C and Ilma, R R and Crowley, G},
  title = {On the origin of pre-reversal enhancement of the zonal equatorial electric field},
  journal = {Annales Geophysicae},
  year = {2009},
  volume = {27},
  pages = {2053-2056},
  doi = {10.5194/angeo-27-2053-2009}
}
Kelley MC and Dao E (2009), "On the local time dependence of the penetration of solar wind-induced electric fields to the magnetic equator", Annales Geophysicae. Vol. 27(8), pp. 3027-3030.
Abstract: For a period of a few hours, the penetration of electric fields of solar wind origin is at its highest efficiency. In November 2003, five days of continuous vertical drift data were obtained at the Jicamarca Radio Observatory. Here we have isolated a range of frequencies centered at a few-hour period for a five-day period and have explored the local time dependence of the penetration, along with the time delay due to magnetospheric effects. We find that the latter ranges from 15 to 25 min. For the local time dependence, we find that the period of anti-correlation is roughly from 21:00 to 04:00 LT, with positive correlation at other local times.
BibTeX:
@article{Kelley2009b,
  author = {Kelley, M. C. and Dao, E.},
  title = {On the local time dependence of the penetration of solar wind-induced electric fields to the magnetic equator},
  journal = {Annales Geophysicae},
  year = {2009},
  volume = {27},
  number = {8},
  pages = {3027-3030},
  doi = {10.5194/angeo-27-3027-2009}
}
Krall J, Huba JD and Martinis CR (2009), "Three-dimensional modeling of equatorial spread F airglow enhancements", Geophysical Research Letters. Vol. 36(10), pp. n/a-n/a.
Abstract: A sequence of 630.0 nm images obtained with the Boston University all-sky imaging system at Arecibo (18.3 N, 66.7 W, 28 N mag) shows equatorial spread F (ESF) airglow depletions evolving into ESF airglow enhancements. Using a combination of a meridional wind and a converging zonal wind, the NRL ionosphere model SAMI3/ESF can reproduce ESF airglow enhancements.
BibTeX:
@article{Krall2009,
  author = {Krall, J. and Huba, J. D. and Martinis, C. R.},
  title = {Three-dimensional modeling of equatorial spread F airglow enhancements},
  journal = {Geophysical Research Letters},
  year = {2009},
  volume = {36},
  number = {10},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2009GL038441},
  doi = {10.1029/2009GL038441}
}
Larsen MF and Fesen CG (2009), "Accuracy issues of the existing thermospheric wind models: can we rely on them in seeking solutions to wind-driven problems?", Annales Geophysicae. Vol. 27(6), pp. 2277-2284.
Abstract: We address the question of the ability of empirical and general circulation model neutral wind profiles in the lower thermosphere to reproduce the observed characteristics of the winds in that part of the atmosphere. The winds in that altitude range are critical for electrodynamic processes, but evaluations of the model winds are generally difficult because of the sparse observational data, which makes an evaluation of the wind predictions over large areas difficult or impossible. In this paper, we use a recently identified characteristic of the winds in the lower thermosphere, namely the enhanced winds and strong shears between 95 and 115 km altitude, as a test of the models, at least in a statistical sense. Our results show that the Horizontal Wind Model (HWM) significantly underestimates the maximum winds and shears in the lower thermosphere, although it has reasonable agreement with the average winds. The NCAR general circulation model used in this study also underestimates the maximum winds and shears significantly when run with standard resolution, as well as producing an unrealistic increase of the wind speed with height. The agreement between the model and the observations improves significantly however, in a statistical sense, when the altitude resolution is increased. The improved height resolution in the model appears to produce a greater improvement in the model predictions than any of the other factors that we examined, such as improving the geomagnetic forcing or the forcing at the lower boundary.
BibTeX:
@article{Larsen2009,
  author = {Larsen, M. F. and Fesen, C. G.},
  title = {Accuracy issues of the existing thermospheric wind models: can we rely on them in seeking solutions to wind-driven problems?},
  journal = {Annales Geophysicae},
  year = {2009},
  volume = {27},
  number = {6},
  pages = {2277-2284},
  doi = {10.5194/angeo-27-2277-2009}
}
Livneh DJ, Seker I, Djuth FT and Mathews JD (2009), "Omnipresent vertically coherent fluctuations in the ionosphere with a possible worldwide-midlatitude extent", Journal of Geophysical Research: Space Physics. Vol. 114(A6), pp. n/a-n/a.
Abstract: Incoherent Scatter Radar power profile observations at Arecibo, Millstone Hill, and the Poker Flat AMISR have revealed the continuous presence of Coherent Omnipresent Fluctuations in the Ionosphere (COFIs) with periods ranging from roughly 30 to 60 minutes and apparent vertical wavelengths increasing with altitude from tens to hundreds of kilometers. Upon high-pass filtering of the Incoherent Scatter Radar power profile and electron concentration data, the COFIs are seen unambiguously and ubiquitously in Arecibo results from 22–23 March 2004, 5–6 June, 21–25 September, and 17–20 November 2005, as well as Millstone Hill results from 4 October to 4 November 2002. The COFIs are strong throughout the F region, often spanning altitudes of 160 km to above 500 km, and are detected day and night in the F2 layer. In fact, the COFIs are seen at every time and altitude that there is sufficient plasma to detect them. The COFIs are also observed at Poker Flat, although the poor signal-to-noise ratio over segments of the data makes it difficult to determine whether or not they are always present. The consistent detection of the COFIs, along with the longitudinal alignment and large latitudinal spread of the observation sites, suggests that these waves are always present over at least North America. This phenomenon appears to have been reported in Total Electron Concentration (TEC) maps of the ionosphere over much of North America Tsugawa et al. (2007b) as well as in airglow images from Arecibo and many other midlatitude sites around the world. These observations give us insight into the horizontal properties of the waves. While Medium-Scale Ionospheric Disturbances (MSTIDs) are generally associated with aurorally generated acoustic gravity waves, the properties of the COFIs may suggest otherwise. We present other possible source mechanisms, notably a possible link to oscillations in the solar wind and magnetosphere. We have observed consistent fluctuations with periods of about an hour observed in magnetic field measurements taken at geosynchronous altitudes by the Geostationary Operational Environmental Satellites (GOES)-10 and -12 satellites, which may be linked to the COFIs. We give corresponding solar wind results from ACE and discuss possible coupling mechanisms.
BibTeX:
@article{Livneh2009,
  author = {Livneh, Dorey J. and Seker, Ilgin and Djuth, Frank T. and Mathews, John D.},
  title = {Omnipresent vertically coherent fluctuations in the ionosphere with a possible worldwide-midlatitude extent},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2009},
  volume = {114},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008JA013999},
  doi = {10.1029/2008JA013999}
}
Martinis C, Baumgardner J, Mendillo M, Su S-Y and Aponte N (2009), "Brightening of 630.0 nm equatorial spread-F airglow depletions", Journal of Geophysical Research: Space Physics. Vol. 114(A6), pp. n/a-n/a.
Abstract: Observations from the Boston University all-sky imaging system at Arecibo, Puerto Rico (18.3°N, 66.7°W, 28°N mag), show an unusual behavior of nighttime 630.0-nm airglow depletions. Associated with equatorial spread-F (ESF), these structures move eastward before reversing their motion and become airglow enhancements. Few other cases have been found, all during December solstices. For the case study presented here, data from the Arecibo incoherent scatter radar and the Republic of China Scientific Satellite (ROCSAT-1) provide supporting information. The radar shows that around local midnight the background zonal and meridional plasma motions reverse to westward and southward, respectively. ROCSAT-1 shows enhanced ion density, i.e., a low-latitude plasma blob, above the bright feature recorded by the all-sky imager, indicating a possible connection between both phenomena. Drifts parallel to the magnetic field are observed only in the region where the enhancement occurs. One possible interpretation of this change in the brightness of the depleted structure involves the influence of northward meridional winds and a reversal in the zonal drift motion, most likely caused by a zonal wind reversal.
BibTeX:
@article{Martinis2009,
  author = {Martinis, Carlos and Baumgardner, Jeffrey and Mendillo, Michael and Su, Shin-Yi and Aponte, Nestor},
  title = {Brightening of 630.0 nm equatorial spread-F airglow depletions},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2009},
  volume = {114},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008JA013931},
  doi = {10.1029/2008JA013931}
}
Morton YT, Zhou Q and van Graas F (2009), "Assessment of second-order ionosphere error in GPS range observables using Arecibo incoherent scatter radar measurements", Radio Science. Vol. 44(1), pp. n/a-n/a.
Abstract: The second-order ionosphere error in GPS range measurements is determined by the electron densities and the geomagnetic field projection onto the GPS signal propagation direction along the GPS signal propagation path. It can be a delay or an advancement error. This paper presents the second-order error analysis based on an extensive collection of electron density profiles measured by the Arecibo incoherent scatter radar and geomagnetic field vectors generated using the International Geomagnetic Reference Field model. The results indicate that the 56–500 km altitude range contributes a maximum of ?1.1 cm for GPS L1 signals arriving from the zenith at Arecibo. For signals coming from the north and south at 10 degree elevation angles, the maximum errors are 0.9 cm and ?3.4 cm, respectively. The maximum of the mean values of the second-order error computed using the entire data set are ?0.55 cm, 0.48 cm, and ?1.74 cm for a signal arriving from the zenith, from the north at 10 degrees elevation, and from the south at 10 degrees elevation, respectively. The paper also discusses the diurnal patterns and geomagnetic activity dependency of the second-order error. Finally, the International Reference Ionosphere model is used to obtain an upper bound estimation of error contributions from the 500–2000 km altitude range.
BibTeX:
@article{Morton2009,
  author = {Morton, Yu T. and Zhou, Qihou and van Graas, Frank},
  title = {Assessment of second-order ionosphere error in GPS range observables using Arecibo incoherent scatter radar measurements},
  journal = {Radio Science},
  year = {2009},
  volume = {44},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008RS003888},
  doi = {10.1029/2008RS003888}
}
Muller H-R, Frisch P, Fields B and Zank G (2009), "The Heliosphere in Time", Space Science Reviews. Vol. 143(1-4), pp. 415-425.
Abstract: Because of the dynamic nature of the interstellar medium, the Sun should have encountered a variety of different interstellar environments in its lifetime. As the solar wind interacts with the surrounding interstellar medium to form a heliosphere, different heliosphere shapes, sizes, and particle contents result from the different environments. Some of the large possible interstellar parameter space (density, velocity, temperature) is explored here with the help of global heliosphere models, and the features in the resulting heliospheres are compared and discussed. The heliospheric size, expressed as distance of the nose of the heliopause to the Sun, is set by the solar wind-interstellar pressure balance, even for extreme cases. Other heliospheric boundary locations and neutral particle results correlate with the interstellar parameters as well. If the H0 clouds identified in the Millennium Arecibo survey are typical of clouds encountered by the Sun, then the Sun spends~99.4% of the time in warm low density ISM, where the typical upwind heliosphere radii are up to two orders of magnitude larger than at present.
BibTeX:
@article{Muller2009,
  author = {Muller, H.-R. and Frisch, P.C. and Fields, B.D. and Zank, G.P.},
  title = {The Heliosphere in Time},
  journal = {Space Science Reviews},
  year = {2009},
  volume = {143},
  number = {1-4},
  pages = {415-425},
  doi = {10.1007/s11214-008-9448-7}
}
Seker I, Livneh DJ and Mathews JD (2009), "A 3-D empirical model of F region Medium-Scale Traveling Ionospheric Disturbance bands using incoherent scatter radar and all-sky imaging at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 114(A6), pp. n/a-n/a.
Abstract: Perhaps the most persistent and prominent of the midlatitude nighttime F region phenomena observed with all-sky imagers is the Medium-Scale Traveling Ionospheric Disturbances (MSTID) that occur when the geomagnetic activity is low. We introduce a simple empirical 3-D model of these bands, which was developed on the basis of an extension of results given by Seker et al. (2008). Seker et al. (2008) reported observational results on the 3-D geometry of MSTID structures found using combined incoherent scatter radar (ISR) and all-sky imager observations over the Arecibo Observatory in Puerto Rico. To confirm and further investigate these findings, a simple empirical 3-D model of nighttime MSTID bands is constructed. We show ISR and all-sky imager results derived from the model, compare them with the actual observations, and highlight the important findings. This model is intended to replicate both the azimuth-scanning ISR and the all-sky imager results and is especially useful in explaining how these complex structures appear in azimuth-scanning ISR results. In addition, confidence in the empirical model allows us to know what to expect from the theory (of MSTID) and to assess how well geomagnetically quiet, nighttime, midlatitude, F region electrodynamics models succeed. Furthermore, the technique described in the paper is not limited to F region or midlatitudes only; it could be applied to any other phenomenon which can be observed by both radar and imager.
BibTeX:
@article{Seker2009,
  author = {Seker, Ilgin and Livneh, Dorey J. and Mathews, John D.},
  title = {A 3-D empirical model of F region Medium-Scale Traveling Ionospheric Disturbance bands using incoherent scatter radar and all-sky imaging at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2009},
  volume = {114},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008JA014019},
  doi = {10.1029/2008JA014019}
}
Sparks J, Janches D, Nicolls M and Heinselman C (2009), "Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 71, pp. 644-652.
Abstract: We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed quantities do not have a strong dependence on entry angle.
BibTeX:
@article{Sparks2009,
  author = {J.J. Sparks and D. Janches and M.J. Nicolls and C.J. Heinselman},
  title = {Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2009},
  volume = {71},
  pages = {644-652},
  doi = {10.1016/j.jastp.2008.08.009}
}
Strelnikova I (2009), "Mesospheric Aerosol Particles: Evidence from Rocket and Radar Techniques". Thesis at: University of Rostock.
BibTeX:
@phdthesis{Strelnikova2009,
  author = {Irina Strelnikova},
  title = {Mesospheric Aerosol Particles: Evidence from Rocket and Radar Techniques},
  school = {University of Rostock},
  year = {2009},
  url = {http://www.iap-kborn.de/fileadmin/user_upload/MAIN-abteilung/optik/Forschung/Doktorarbeiten/Strelnikova-Diss-2009.pdf}
}
Swartz WE, Kelley MC and Aponte N (2009), "E- and F-region coupling between an intense sporadic E layer and a mesoscale traveling ionospheric disturbance", Annales Geophysicae. Vol. 27(6), pp. 2475-2482.
Abstract: Considerable controversy exists concerning the relative roles of the E- and F-regions in controlling irregularity formation in the mid-latitude ionosphere, largely because electric fields due to a plasma instability in one region may map to the other if the perpendicular scales are sufficiently large. In this paper we look at a particularly fortuitous data set in which both E- and F-region observations were made using incoherent scatter radar, GPS, lidar, and coherent scatter radar. In this event, a dense, patchy sporadic E layer was detected that exhibited type I (two-stream) coherent echoes while, at the same time, the F-layer plasma was highly structured with plasma drifts of hundreds of m/s. We examine this event in the context of a mesoscale traveling ionospheric disturbance. The data presentation will be followed by comparison with current theories for coupling between these two regions.
BibTeX:
@article{Swartz2009,
  author = {Swartz, W. E. and Kelley, M. C. and Aponte, N.},
  title = {E- and F-region coupling between an intense sporadic E layer and a mesoscale traveling ionospheric disturbance},
  journal = {Annales Geophysicae},
  year = {2009},
  volume = {27},
  number = {6},
  pages = {2475-2482},
  url = {http://www.ann-geophys.net/27/2475/2009/},
  doi = {10.5194/angeo-27-2475-2009}
}
Abdu M, Brum C, Batista I, Sobral J, de Paula E and Souza J (2008), "Solar flux effects on equatorial ionization anomaly and total electron content over Brazil: Observational results versus IRI representations", Advances in Space Research . Vol. 42(4), pp. 617-625.
Abstract: The F layer critical frequency (foF2) as measured by Digisondes in the equatorial and low latitude locations in Brazil is analyzed to investigate the seasonal and solar flux controls of the intensity of the equatorial ionization anomaly (EIA) in the equinoctial month of March. The analysis also included the total electron content (TEC) as measured by a GPS receiver operated at the EIA crest location. The foF2 data set covered a period of large solar flux variation from 1996 to 2003, while the GPS TEC data was for a period in 2002-2003 when the solar flux parameter F10.7 underwent large variations, permitting in both cases an examination of the solar flux effects on these parameters. The seasonal variation pattern in TEC shows a maximum in equinoctial months and a minimum in June solstice, with similar variations for foF2. The solar flux dependence of the TEC is a maximum during equinoxes, especially for post-sunset TEC values at times when the latitudinal distribution is controlled by the equatorial evening plasma fountain processes. Significant variations with local time are found in the degree of solar flux dependence for both the TEC and EIA. The EIA intensity shows large dependence on F10.7 during post-sunset to midnight hours. These results are discussed in comparison with their corresponding IRI representations.
BibTeX:
@article{Abdu2008,
  author = {M.A. Abdu and C.G.M. Brum and I.S. Batista and J.H.A. Sobral and E.R. de Paula and J.R. Souza},
  title = {Solar flux effects on equatorial ionization anomaly and total electron content over Brazil: Observational results versus IRI representations},
  journal = {Advances in Space Research },
  year = {2008},
  volume = {42},
  number = {4},
  pages = {617-625},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117708000999},
  doi = {10.1016/j.asr.2007.09.043}
}
Bhatt AN, Nicolls MJ, Sulzer MP and Kelley MC (2008), "Observations of Plasma Line Splitting in the Ionospheric Incoherent Scatter Spectrum", Physical Review Letters. Vol. 100, pp. 045005. American Physical Society.
Abstract: Wide-bandwidth ionospheric incoherent scatter (IS) spectra obtained using the Arecibo IS radar show the occurrence of a split in the plasma line (i.e., two plasma lines) when the plasma frequency is close to the second harmonic of the electron gyrofrequency. This split is predicted in the IS theory for a magnetized plasma, but observations have never been reported. Here we present the experimental results and theoretical calculations supporting the observations. These results may assist in understanding the behavior of Langmuir waves in the magnetized plasma and are a validation of what historically was a somewhat controversial aspect of the IS theory.
BibTeX:
@article{Bhatt2008,
  author = {Bhatt, Asti N. and Nicolls, Michael J. and Sulzer, Michael P. and Kelley, Michael C.},
  title = {Observations of Plasma Line Splitting in the Ionospheric Incoherent Scatter Spectrum},
  journal = {Physical Review Letters},
  publisher = {American Physical Society},
  year = {2008},
  volume = {100},
  pages = {045005},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.100.045005},
  doi = {10.1103/PhysRevLett.100.045005}
}
Dyrud L, Behnke R, Kepko E, Sulzer M and Zafke S (2008), "Ionospheric ULF oscillations driven from above Arecibo", Geophysical Research Letters. Vol. 35, pp. L14101.
Abstract: Understanding the coupling between the surface of the sun, the solar corona, the solar wind, the Earth's magnetosphere and ionosphere is a major focus of today's space research. Over 20 years ago, detailed observations of the ionospheric electron density at Arecibo revealed short period fluctuations (3 minutes), but their cause was never determined. Also, in the past 20 years a number of papers have reported observations of discrete (1–5 mHz) waves at persistent “magic frequencies” in magnetometer data and radar observations of ionospheric drift. Such observations have been generally interpreted as standing waves excited by magnetospheric cavity compressional modes. This assertion has been recently challenged by suggestions that these magic frequencies are not standing waves, but are due to inherent oscillations in the solar wind. Here we show that a subset of discrete 1.7 mHz oscillations in the solar wind plasma density are likely transmitted via a passive magnetospheric oscillation, and are observed as small amplitude (0.1%), discrete 1.7 mHz oscillations in the ionospheric plasma line using the extremely sensitive ionospheric measurements over Arecibo, Puerto Rico. We present over three hours of data using the electron plasma line component of the Arecibo radar incoherent scatter radar spectrum, solar wind number density from the WIND satellite, and magnetic field from the GOES satellite. This paper demonstrates a link between the solar wind and low latitude ionosphere.
BibTeX:
@article{Dyrud2008,
  author = {Dyrud, LP and Behnke, R and Kepko, EL and Sulzer, M and Zafke, S},
  title = {Ionospheric ULF oscillations driven from above Arecibo},
  journal = {Geophysical Research Letters},
  year = {2008},
  volume = {35},
  pages = {L14101},
  url = {http://dx.doi.org/10.1029/2008GL034073},
  doi = {10.1029/2008GL034073}
}
Dyrud L and Janches D (2008), "Modeling the meteor head echo using Arecibo radar observations", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 70(13), pp. 1621-1632.
Abstract: This paper reports results obtained using a combined set of models to determine meteoroid properties by comparing expected and observed meteor head-echo signal-to-noise ratio (SNR) and line-of-sight Doppler velocity as measured in high-power and large-aperture (HPLA) radar observations. For this task we model: (1) meteor ablation and ionization processes, (2) meteor head-echo radar cross-section (RCS), (3) the radar equation, and (4) the radar antenna gain pattern, together with an automated least-squares fitting procedure to estimate meteoroid and observation parameters (i.e. aspect angle, location within the radar beam, etc.). We compared our simulated results with 236 head-echo events observed using the Arecibo 430 MHz radar in Puerto Rico. We found good agreement between modeled and observed SNR versus meteor altitude profiles for a broad range of head-echo observations. We also find reasonable agreement between meteoroid mass distributions resulting from these models and estimated using dynamical arguments, with the dynamical mass generally resulting in lower values by about 1–2 orders of magnitude. A characteristic of our methodology is that we can trace back the original mass and velocity of the meteoroid “above” the atmosphere (?150 km altitude) required to produce the observed meteors. We find that, the original mass is required to be, on average, 1–2 orders of magnitude larger than that at the time of observation, and 3 orders of magnitude larger than estimated using dynamical equations. These results suggest that many meteor head echoes are observed towards the end of the particle's life, which has significant implications for the use of these observations for the determination of meteoroid properties. The automated fitting procedure is very sensitive to the antenna pattern, and therefore allows for precise estimates of the location of the meteoroid's trajectory within the Arecibo radar beam. The results indicate a noticeable, but weak, dependence between the distance of the particle's trajectory from the center of the beam (i.e. maximum gain) and the mass and velocity of the meteoroid. This suggests that the Arecibo radar is not particularly biased toward a specific velocity population of meteoroids (i.e. high velocity) as has been suggested in previous work.
BibTeX:
@article{Dyrud2008a,
  author = {Lars Dyrud and Diego Janches},
  title = {Modeling the meteor head echo using Arecibo radar observations},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2008},
  volume = {70},
  number = {13},
  pages = {1621-1632},
  doi = {10.1016/j.jastp.2008.06.016}
}
Fentzke JT and Janches D (2008), "A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function in the MLT observed at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 113(A3), pp. n/a-n/a.
Abstract: In this paper, we present a modeling and observational study of the micrometeor input function with a focus on understanding how each of the extraterrestrial sporadic meteoroid sources contributes to the observed meteoric flux in the Mesosphere and Lower Thermosphere (MLT) atmospheric region. For this purpose, we expand the model presented by Janches et al. (2006) using a Monte Carlo technique and incorporating: 1) a widely accepted global mass flux, which is divided into different proportions among the known sporadic meteoroid sources as the initial input above Earth’s atmosphere; 2) contemporary knowledge on the source's velocity and radiant distributions; and 3) the full integration of the canonical meteor equations that describe the meteoroid entry and ablation physics. In addition, we constrain the initial input through a comparison of our modeled results with meteor observations obtained with the 430 MHz High Power and Large Aperture (HPLA) Arecibo radar in Puerto Rico that covers all seasons. The predicted meteor rates and velocity distributions are in excellent agreement with the observed ones without the need for any additional normalization factor. Our results indicate that although the Earth’s Apex centered radiant source, which is characterized by high geocentric speeds (?55 km/s), appears to be ?33% of the meteoroids in the Solar System at 1 AU, it accounts for ?60% of the meteors observed by the Arecibo HPLA radar in the atmosphere. The remaining 40% of observed meteors originate mostly from the Helion and Anti-Helion sources, with a very small, but constant during the day, contribution of the South and North Toroidal sources. These results also suggest that particles smaller than ?10?3?g with slow velocities (<30 km/s) will not significantly ablate and never become observable meteors. The motivation of this effort is to construct a new and more precise MIF model needed for the subsequent modeling of the atmospheric phenomena related to the meteoric flux.
BibTeX:
@article{Fentzke2008,
  author = {Fentzke, Jonathan T. and Janches, Diego},
  title = {A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function in the MLT observed at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A3},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012531},
  doi = {10.1029/2007JA012531}
}
Friedrich M, Fankhauser M, Oyeyemi E and McKinnell LA (2008), "A neural network-based ionospheric model for Arecibo", Advances in Space Research. Vol. 42(4), pp. 776-781. Elsevier Science.
Abstract: The Arecibo Observatory (18°N, 66°W) has the world’s largest single dish antenna (300 m diameter). Beyond radio astronomy it can also operate as an incoherent scatter radar and in that mode its figure-of-merit makes it also one of the most powerful world-wide. For the present purpose all electron density data available on the web, from the beginning with the first erratic measurements in 1966 up to 2004 inclusive, were downloaded. The measurements range from about 100 km to beyond 700 km and are essentially evenly distributed, i.e. not dedicated to measure specific geophysical events. From manually edited/inspected data a neural network (NN) was established with season, hour of the day, solar activity and Kp as the input parameters. The performance of this model is checked against a – likewise NN based – global model of foF2, a measure of the maximum electron density of the ionosphere. Considering the diverse data sources and assumptions of the two models it can be concluded that they agree remarkably well.
BibTeX:
@article{Friedrich2008,
  author = {Friedrich, M and Fankhauser, M and Oyeyemi, E and McKinnell, L A},
  title = {A neural network-based ionospheric model for Arecibo},
  journal = {Advances in Space Research},
  publisher = {Elsevier Science},
  year = {2008},
  volume = {42},
  number = {4},
  pages = {776-781},
  doi = {10.1016/j.asr.2007.07.018}
}
Fritts DC and Janches D (2008), "Dual-beam measurements of gravity waves over Arecibo: Reevaluation of wave structure, dynamics, and momentum fluxes", Journal of Geophysical Research: Atmospheres. Vol. 113(D5), pp. n/a-n/a.
Abstract: A previous study by Zhou and Morton (2006) employed dual-beam incoherent scatter radar measurements of radial velocities at the Arecibo Observatory to study the structure, dynamics, and momentum fluxes of gravity waves in the mesosphere and lower thermosphere for ?8 h on 28 July 2001. Because of erroneous assumptions about wave character and inferences of the relationship between radial velocities, however, the advertised results of this previous study are largely in error. The purposes of the present study are both to point out these errors to help avoid such pitfalls in the future and to provide a new interpretation of these data, which represent a very interesting case study of gravity wave dynamics at these altitudes. Specific findings of the present study (largely in contradiction to the previous analysis) include (1) the ?15-min oscillation was apparently a large-amplitude Doppler-ducted gravity wave structure propagating at one or two maxima of the westward large-scale wind present during the event; (2) the gravity wave exhibited a deep and coherent vertical phase structure, except between the two westward wind maxima at later times, entirely inconsistent with proximity to a critical level; (3) the dominant motions within the gravity wavefield were vertical velocities up to ?10 m s–1, except for inferred horizontal motions where the vertical motions changed phase and above and below the vertical velocity maxima, as dictated by the continuity equation; (4) there were likely no regions of dynamical instability accompanying these ducted wave motions; and (5) momentum fluxes due to this wave motion were small, despite its very large amplitude.
BibTeX:
@article{Fritts2008,
  author = {Fritts, David C. and Janches, Diego},
  title = {Dual-beam measurements of gravity waves over Arecibo: Reevaluation of wave structure, dynamics, and momentum fluxes},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2008},
  volume = {113},
  number = {D5},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JD008896},
  doi = {10.1029/2007JD008896}
}
Janches D, Close S and Fentzke JT (2008), "A comparison of detection sensitivity between ALTAIR and Arecibo meteor observations: Can high power and large aperture radars detect low velocity meteor head-echoes", Icarus. Vol. 193, pp. 105-111.
Abstract: Meteor head-echo observations using High Power and Large Aperture (HPLA) radars have been routinely used for micrometeor studies for over a decade. The head-echo is a signal from the radar-reflective plasma region traveling with the meteoroid and its detection allows for very precise determination of instantaneous meteor altitude, velocity and deceleration. Unlike specular meteor radars (SMR), HPLA radars are diverse instruments when compared one to another. The operating frequencies range from 46 MHz to 1.29 GHz while the antenna configurations changes from 18,000 dipoles in a 300 mâ300 m300 mâ300 m square array, phase arrays of dipoles to single spherical or parabolic dishes of various dimensions. Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34–42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi:10.1016/j.icarus.2006.09.07] recently showed, by utilizing a head-echo plasma-based model, the presence of instrumental biases in the ALTAIR VHF radar system against detecting meteors produced by very small particles (<1 ug) moving at slow (~20 km/s) velocities due to the low head echo radar cross-section (RCS) associated with these particles. In this paper we apply the same methodology to the Arecibo 430 MHz radar and compare the results with those presented by Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi:10.1016/j.icarus.2006.09.07]. We show that, if the methodology applied by Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34–42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi:10.1016/j.icarus.2006.09.07] is accurate, for particles at least 1 ug or heavier, while the bias may exist for the ALTAIR measurements, it does not exist in the Arecibo data due to its greater sensitivity.
BibTeX:
@article{Janches2008,
  author = {Janches, D and Close, S and Fentzke, J T},
  title = {A comparison of detection sensitivity between ALTAIR and Arecibo meteor observations: Can high power and large aperture radars detect low velocity meteor head-echoes},
  journal = {Icarus},
  year = {2008},
  volume = {193},
  pages = {105-111},
  url = {http://dx.doi.org/10.1016/j.icarus.2007.08.022},
  doi = {10.1016/j.icarus.2007.08.022}
}
Emmert JT, Drob DP, Shepherd GG, Hernandez G, Jarvis MJ, Meriwether JW, Niciejewski RJ, Sipler DP and Tepley CA (2008), "DWM07 global empirical model of upper thermospheric storm-induced disturbance winds", Journal of Geophysical Research: Space Physics. Vol. 113(A11), pp. n/a-n/a.
Abstract: We present a global empirical disturbance wind model (DWM07) that represents average geospace-storm-induced perturbations of upper thermospheric (200–600 km altitude) neutral winds. DWM07 depends on the following three parameters: magnetic latitude, magnetic local time, and the 3-h Kp geomagnetic activity index. The latitude and local time dependences are represented by vector spherical harmonic functions (up to degree 10 in latitude and order 3 in local time), and the Kp dependence is represented by quadratic B-splines. DWM07 is the storm time thermospheric component of the new Horizontal Wind Model (HWM07), which is described in a companion paper. DWM07 is based on data from the Wind Imaging Interferometer on board the Upper Atmosphere Research Satellite, the Wind and Temperature Spectrometer on board Dynamics Explorer 2, and seven ground-based Fabry-Perot interferometers. The perturbation winds derived from the three data sets are in good mutual agreement under most conditions, and the model captures most of the climatological variations evident in the data.
BibTeX:
@article{JGRA:JGRA19582,
  author = {Emmert, J. T. and Drob, D. P. and Shepherd, G. G. and Hernandez, G. and Jarvis, M. J. and Meriwether, J. W. and Niciejewski, R. J. and Sipler, D. P. and Tepley, C. A.},
  title = {DWM07 global empirical model of upper thermospheric storm-induced disturbance winds},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A11},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2008JA013541},
  doi = {10.1029/2008JA013541}
}
Drob DP, Emmert JT, Crowley G, Picone JM, Shepherd GG, Skinner W, Hays P, Niciejewski RJ, Larsen M, She CY, Meriwether JW, Hernandez G, Jarvis MJ, Sipler DP, Tepley CA, O'Brien MS, Bowman JR, Wu Q, Murayama Y, Kawamura S, Reid IM and Vincent RA (2008), "An empirical model of the Earth's horizontal wind fields: HWM07", Journal of Geophysical Research: Space Physics. Vol. 113(A12), pp. n/a-n/a.
Abstract: The new Horizontal Wind Model (HWM07) provides a statistical representation of the horizontal wind fields of the Earth's atmosphere from the ground to the exosphere (0–500 km). It represents over 50 years of satellite, rocket, and ground-based wind measurements via a compact Fortran 90 subroutine. The computer model is a function of geographic location, altitude, day of the year, solar local time, and geomagnetic activity. It includes representations of the zonal mean circulation, stationary planetary waves, migrating tides, and the seasonal modulation thereof. HWM07 is composed of two components, a quiet time component for the background state described in this paper and a geomagnetic storm time component (DWM07) described in a companion paper.
BibTeX:
@article{JGRA:JGRA19649,
  author = {Drob, D. P. and Emmert, J. T. and Crowley, G. and Picone, J. M. and Shepherd, G. G. and Skinner, W. and Hays, P. and Niciejewski, R. J. and Larsen, M. and She, C. Y. and Meriwether, J. W. and Hernandez, G. and Jarvis, M. J. and Sipler, D. P. and Tepley, C. A. and O'Brien, M. S. and Bowman, J. R. and Wu, Q. and Murayama, Y. and Kawamura, S. and Reid, I. M. and Vincent, R. A.},
  title = {An empirical model of the Earth's horizontal wind fields: HWM07},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A12},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2008JA013668},
  doi = {10.1029/2008JA013668}
}
Lee MC, Pradipta R, Burke WJ, Labno A, Burton LM, Cohen JA, Dorfman SE, Coster AJ, Sulzer MP and Kuo SP (2008), "Did Tsunami-Launched Gravity Waves Trigger Ionospheric Turbulence over Arecibo?", Journal of Geophysical Research: Space Physics. Vol. 113(A1), pp. n/a-n/a.
Abstract: We report on measurements of ionospheric plasma dynamics conducted at the Arecibo Observatory between 20:00 and 24:00 local time (LT) on December 25 and 26, 2004 using the 430 MHz incoherent scatter radar (ISR). For interpretive purposes these measurements are supported by data from two nearby ionosondes and Global Positioning System (GPS) satellites. The ISR detected different ionospheric behaviors during the vertical-transmission periods on the consecutive, magnetically quiet nights. On the night of December 25 the ionosphere descended smoothly and spread F signatures faded. For about two hours on the following evening the bottomside ionosphere rose by ~50 km, inducing plasma irregularities and intense spread F. Alternating cycles of bottom-side plasma rising and falling persisted through the remainder of the experiments. We postulate that this sinusoidal behavior is a response to gravity waves propagating above Puerto Rico. Nearly simultaneous data from two nearby stations show that GPS signals were modified by variations in total electron content (TEC) indicating the presence of traveling ionospheric disturbances (TIDs). The December 26 experiments were conducted about a day after an MW = 9.2 earthquake launched tsunami waves first across the Indian, then into the Atlantic and Pacific Oceans. We suggest that coupling at the tsunami sea-air interface launched gravity waves that propagated for great distances beneath the mesopause. GPS data recorded TEC variation in Asia, Europe, and the Caribbean, suggesting that TIDs were induced on a global scale at the wake of tsunami-launched gravity waves. Energy from imperfectly ducted gravity waves leaked into the ionosphere, partially over Puerto Rico. The wind-velocity field of these gravity waves caused local ionospheric plasma to rise, seeding bottomside irregularities via the generalized Rayleigh-Taylor instability.
BibTeX:
@article{Lee2008,
  author = {Lee, M. C. and Pradipta, R. and Burke, W. J. and Labno, A. and Burton, L. M. and Cohen, J. A. and Dorfman, S. E. and Coster, A. J. and Sulzer, M. P. and Kuo, S. P.},
  title = {Did Tsunami-Launched Gravity Waves Trigger Ionospheric Turbulence over Arecibo?},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012615},
  doi = {10.1029/2007JA012615}
}
Lee MC, Pradipta R, Burke WJ, Labno A, Burton LM, Cohen JA, Dorfman SE, Coster AJ, Sulzer MP and Kuo SP (2008), "Correction to Did tsunami-launched gravity waves trigger ionospheric turbulence over Arecibo?", Journal of Geophysical Research: Space Physics. Vol. 113(A0), pp. n/a-n/a.
BibTeX:
@article{Lee2008a,
  author = {Lee, M. C. and Pradipta, R. and Burke, W. J. and Labno, A. and Burton, L. M. and Cohen, J. A. and Dorfman, S. E. and Coster, A. J. and Sulzer, M. P. and Kuo, S. P.},
  title = {Correction to Did tsunami-launched gravity waves trigger ionospheric turbulence over Arecibo?},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A0},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2008JA013044},
  doi = {10.1029/2008JA013044}
}
Leonovich LA and Tashchilin AV (2008), "Disturbances in the topside ionosphere during solar flares", Geomagnetism and Aeronomy. Vol. 48, pp. 793-802.
Abstract: The results of studying the ionospheric response to solar flares, obtained from the data of the GPS signal observations and incoherent scatter radars and as a result of the model calculations, are presented. It is shown that, according to the GPS data, a flare can cause a decrease in the electron content at altitudes of the topside ionosphere (h > 300 km). Similar effects of formation of a negative disturbance in the ionospheric F region were also observed during the solar flares of May 21 and 23, 1967, with the Arecibo incoherent scatter radar. The mechanism by which negative disturbances appear in the topside ionosphere during solar flares has been studied in this work based on the theoretical model of the ionosphere-plasmasphere coupling. It has been indicated that the formation of the electron density negative disturbance in the topside ionosphere is caused by an intense removal of O+ ions into the overlying plasmasphere under the action of an abrupt increase in the ion production rate and thermal expansion of the ionospheric plasma.
BibTeX:
@article{Leonovich2008,
  author = {Leonovich, L A and Tashchilin, A V},
  title = {Disturbances in the topside ionosphere during solar flares},
  journal = {Geomagnetism and Aeronomy},
  year = {2008},
  volume = {48},
  pages = {793-802},
  url = {http://dx.doi.org/10.1134/S001679320806008X},
  doi = {10.1134/s001679320806008x}
}
Liu L, He M, Wan W and Zhang M-L (2008), "Topside ionospheric scale heights retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation measurements", Journal of Geophysical Research: Space Physics. Vol. 113(A10), pp. n/a-n/a.
Abstract: The vertical scale height (VSH) in the topside ionosphere can be derived from electron density profiles. In this study, the electron density profiles retrieved from the COSMIC/FORMOSAT-3 (a Constellation Observing System for Meteorology, Ionosphere, and Climate mission; C/F3 for short) ionospheric radio occultation (IRO) observations have been collected to investigate the local time, seasonal, latitudinal, and longitudinal variations of the VSH. With the postprocessed C/F3 IRO electron density profiles during the interval from day of year (DOY) 194 in 2006 to DOY 60 in 2008, we conduct an analysis on the behaviors of VSH at an altitude of 400 km. There are appreciable latitudinal variations in VSH. A new finding is a significant peak around dip equator during daytime in four seasons. Away from the equatorial peak, it is obvious that the VSH generally increases at higher latitudes. The equatorial VSH undergoes a significant diurnal variation with a local noon maximum. The peak shifts to sunrise time with increasing dip latitude, and the values of daytime VSH become comparable with those at nighttime at low latitude in both hemispheres, which is somewhat different from the feature revealed from Arecibo incoherent scatter radar observations. One of the crucial findings in our results is the most outstanding feature of VSH, that is, the presence of a substantial longitudinal structure in equatorial regions. A wave-like longitudinal feature is found in equatorial VSH during the daytime in four seasons, while it becomes weaker or absent at other local time intervals and at higher latitudes. This investigation also confirms that the behaviors of VSH are not strongly consistent with those of the neutral or plasma-scale heights.
BibTeX:
@article{Liu2008,
  author = {Liu, Libo and He, Maosheng and Wan, Weixing and Zhang, Man-Lian},
  title = {Topside ionospheric scale heights retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation measurements},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A10},
  pages = {n/a-n/a},
  doi = {10.1029/2008JA013490}
}
Liu G, Shepherd GG and Tepley CA (2008), "Variations of the tropical O(1S) nightglow as observed with the Arecibo Observatory photometer and WINDII on UARS", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 70(10), pp. 1309-1317.
Abstract: This work investigates the tropical O(1S) nightglow variations utilizing observations from the Wind Imaging Interferometer (WINDII) operated on the Upper Atmosphere Research Satellite (UARS) and photometers installed at the Arecibo Observatory (18°N, 67°W) in Puerto Rico. Both are long-term datasets, but there is limited overlap in the dates of observation. Their simultaneous observations of column integrated emission rate on 6 continuous days in 1993 have a consistent difference at some times. The ground-based emission rate includes the F-region component of the O(1S) emission, while the vertical profiles of WINDII allow the E- and F-region emission to be separated. This allows subtraction of the F-region emission rate for the Arecibo measurements and leads to a decisive study of the O(1S) nightglow variation. The monthly averaged integrated emission rates (excluding the F-region component) are computed for WINDII from November 1991 to August 1997 and for the photometer data through 1983–2004. The emission rates between WINDII and Arecibo exhibit a similar semiannual variation. They have maxima at the two equinoxes and minima at solstices with a larger maximum in spring than in fall, while the WINDII averaged emission rates are larger than the apparent photometer averages by a factor of 2 for the mean values. The satellite WINDII and ground-based Arecibo instruments sample local time hours differently, but the local time influence is found not to be the origin of the difference. Because the observation periods are for different solar cycle intervals for the WINDII and Arecibo datasets, the influence of the solar F10.7 cm flux on the O(1S) nightglow emission rate is also studied. The comparison between WINDII and Arecibo further offers a possibility to assess the atmospheric transmittance for these ground-based observations. The MODTRAN estimated transmittance of 0.7 is reasonably consistent with the difference in the O(1S) nightglow emission rate between WINDII and the Arecibo photometer.
BibTeX:
@article{Liu2008a,
  author = {Guiping Liu and Gordon G. Shepherd and Craig A. Tepley},
  title = {Variations of the tropical O(1S) nightglow as observed with the Arecibo Observatory photometer and WINDII on UARS},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2008},
  volume = {70},
  number = {10},
  pages = {1309-1317},
  doi = {10.1016/j.jastp.2008.03.001}
}
Lu G, Goncharenko LP, Richmond AD, Roble RG and Aponte N (2008), "A dayside ionospheric positive storm phase driven by neutral winds", Journal of Geophysical Research: Space Physics. Vol. 113(A8), pp. A08304 (7 pages).
Abstract: This paper presents observations and numerical simulations of ionospheric and thermospheric disturbances associated with a moderate geomagnetic storm on 10 September 2005. During the event, the incoherent radars located in Millstone Hill and Arecibo observed a dayside positive storm phase as manifested by the enhanced electron density in the F region. The universal time (UT)-altitude profile of electron density measured by both radars displayed a structure that closely resembles the Greek letter A. A similar structure is also reproduced by the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM). This peculiar electron density distribution is found to be associated with vertical ion drift, which initially was upward and then became downward. Using realistic time-dependent ionospheric convection and auroral precipitation as inputs, the TIEGCM reveals that the primary cause of the positive storm response was the enhanced meridional neutral wind rather than the penetration magnetospheric electric field. This study reiterates the importance of neutral wind effects on ionospheric disturbance.
BibTeX:
@article{Lu2008,
  author = {Lu, G. and Goncharenko, L. P. and Richmond, A. D. and Roble, R. G. and Aponte, N.},
  title = {A dayside ionospheric positive storm phase driven by neutral winds},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A8},
  pages = {A08304 (7 pages)},
  url = {http://dx.doi.org/10.1029/2007JA012895},
  doi = {10.1029/2007JA012895}
}
Mathews J D and. Briczinski SJ, Meisel DD and Heinselman CJ (2008), "Radio and Meteor Science Outcomes From Comparisons of Meteor Radar Observations at AMISR Poker Flat, Sondrestrom, and Arecibo", Earth, Moon, and Planets. Vol. 102, pp. 365-372. Springer Netherlands.
Abstract: Radio science and meteor physics issues regarding meteor “head-echo” observations with high power, large aperture (HPLA) radars, include the frequency and latitude dependency of the observed meteor altitude, speed, and deceleration distributions. We address these issues via the first ever use and analysis of meteor observations from the Poker Flat AMISR (PFISR: 449.3 MHz), Sondrestrom (SRF: 1,290 MHz), and Arecibo (AO: 430 MHz) radars. The PFISR and SRF radars are located near the Arctic Circle while AO is in the tropics. The meteors observed at each radar were detected and analyzed using the same automated FFT periodic micrometeor searching algorithm. Meteor parameters (event altitude, velocity, and deceleration distributions) from all three facilities are compared revealing a clearly defined altitude “ceiling effect” in the 1,290 MHz results relative to the 430/449.3 MHz results. This effect is even more striking in that the Arecibo and PFISR distributions are similar even though the two radars are over 2,000 times different in sensitivity and at very different latitudes, thus providing the first statistical evidence that HPLA meteor radar observations are dominated by the incident wavelength, regardless of the other radar parameters. We also offer insights into the meteoroid fragmentation and “terminal” process.
BibTeX:
@article{Mathews2008,
  author = {Mathews, J D and. Briczinski, S J and Meisel, D D and Heinselman, C J},
  title = {Radio and Meteor Science Outcomes From Comparisons of Meteor Radar Observations at AMISR Poker Flat, Sondrestrom, and Arecibo},
  journal = {Earth, Moon, and Planets},
  publisher = {Springer Netherlands},
  year = {2008},
  volume = {102},
  pages = {365-372},
  doi = {10.1007/s11038-007-9168-0}
}
Mishin E and Milikh G (2008), "Blue Jets: Upward Lightning", Space Science Reviews. Vol. 137(1-4), pp. 473-488.
Abstract: Blue jets are beams of blue light propagating from the tops of active thunderclouds up to altitudes of ~50 km. They resemble tall trees with quasi-vertical trunk and filamentary branches. Their apparent speeds are in the range of 10 s to 100 s km/s. Other events, having essentially lower terminal altitudes (<26 km), are named blue starters. These phenomena represent the first documented class of upward electrical discharges in the stratosphere. Some of upward discharges, termed gigantic jets, propagate into the lower ionosphere at much higher speeds in the final phase. We describe salient features of the upward discharges in the atmosphere, give an assessment of the theories of their development, and discuss the consequences for the electrodynamics and chemistry of the stratosphere. We argue that this upward lightning phenomenon can be understood in terms of the bi-directional leader, emerging from the anvil.
BibTeX:
@article{Mishin2008,
  author = {Mishin, EvgenyV. and Milikh, GennadyM.},
  title = {Blue Jets: Upward Lightning},
  journal = {Space Science Reviews},
  year = {2008},
  volume = {137},
  number = {1-4},
  pages = {473-488},
  doi = {10.1007/s11214-008-9346-z}
}
Nikoukar R, Kamalabadi F, Kudeki E and Sulzer M (2008), "An efficient near-optimal approach to incoherent scatter radar parameter estimation", Radio Science. Vol. 43(5), pp. n/a-n/a.
Abstract: We present a computationally efficient, near-optimal approach to the estimation of ionospheric parameters from incoherent scatter radar measurements. The method consists of removing the range smearing of ionospheric autocorrelation function via a set of 1-D deconvolutions and performing nonlinear least squares fitting on the deconvolved autocorrelation functions. To stabilize the solution in the presence of noise, we incorporate regularization techniques. The computational cost is reduced significantly by estimating the ionospheric parameters at individual altitudes, in comparison to full-profile-type analysis, which attempts to estimate ionospheric parameters at all altitudes simultaneously. The performance of the new technique is evaluated in a numerical example and is shown to give estimates of almost equal quality as the full-profile technique but at a 95% reduction in computation.
BibTeX:
@article{Nikoukar2008,
  author = {Nikoukar, Romina and Kamalabadi, Farzad and Kudeki, Erhan and Sulzer, Michael},
  title = {An efficient near-optimal approach to incoherent scatter radar parameter estimation},
  journal = {Radio Science},
  year = {2008},
  volume = {43},
  number = {5},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007RS003724},
  doi = {10.1029/2007RS003724}
}
Pradipta R, Cohen JA, Lee MC, Labno A, Burton LM, Riddolls RJ, Batishchev OV, Coster AJ, Burke WJ, Starks MJ, Sulzer MP and Kuo SP (2008), "Space plasma disturbances caused by NAU-launched whistler waves", Physica Scripta. Vol. T132, pp. 014031 (9pp).
Abstract: Radio signals from Naval (NAU) transmitter in Puerto Rico can interact effectively with naturally occurring or HF heater wave-induced large-scale ionospheric irregularities, allowing them to propagate as whistler-modes in the ionosphere and to the inner radiation belts. NAU-generated whistler-modes have intensities sufficient to parametrically excite lower hybrid waves and ten-meter and meter-scale ionospheric irregularities over Arecibo.
Subsequent heating of electrons and ions by the lower hybrid waves yield a sequence of ionospheric plasma effects such as airglow, short-scale density depletion and plasma line enhancements in a range of altitudes which far exceed that caused by the HF heater. Furthermore, they can interact with trapped energetic electrons in inner radiation belts at L = 1.35 and trigger precipitation of electrons into the lower ionosphere. We suggest that
disturbances in the ionosphere above NAU caused by whistler-mode signals can significantly affect heater-induced perturbations and partially explain unique results obtained at other heater sites.
BibTeX:
@article{Pradipta2008,
  author = {R Pradipta and J A Cohen and M C Lee and A Labno and L M Burton and R J Riddolls and O V Batishchev and A J Coster and W J Burke and M J Starks and M P Sulzer and S P Kuo},
  title = {Space plasma disturbances caused by NAU-launched whistler waves},
  journal = {Physica Scripta},
  year = {2008},
  volume = {T132},
  pages = {014031 (9pp)},
  url = {http://iopscience.iop.org.sci-hub.org/1402-4896/2008/T132/014031/},
  doi = {10.1088/0031-8949/2008/T132/014031}
}
Raizada S, Sulzer MP, Tepley CA, Gonzalez SA and Nicolls MJ (2008), "Inferring D region parameters using improved incoherent scatter radar techniques at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 113(A12), pp. n/a-n/a.
Abstract: With the increased sensitivity and bandwidth, Arecibo 430 MHz incoherent scatter radar was run on 23 July 2006 using two radar modes with a focus on measuring D region parameters. One mode measured the ion line spectra over D region altitudes; the other mode was used as a new way to calibrate the electron densities in the D region and also to correct the ion line spectra. The ion line primarily provided a power profile connecting the D region to altitudes where the plasma line is useful. The plasma line provided the absolute electron density, used in the lower altitudes for calibration, and at F region altitudes for determining the baseline level in the D region spectra due to the folding-in of F region scattered power. It is found that the electron line contribution is about 1–3 times the ion line between 60–75 km altitude ranges. Electron concentration was found to be in the range of a few hundred to 5000 cm?3 in the 65–90 km altitude range. The new technique agrees well with the previous measurements. The D region spectral widths were used to calculate the ratio of negative ion to electron concentration (?). Between 0900 and 1100 LT, a 4 km thick layer of negative ions was observed with ? ? 1.6 ± 0.3 around 73–77 km. In the altitude range of 81–91 km, we inferred temperatures ? 195–215 K using ion-neutral collision frequencies determined from the spectral widths.
BibTeX:
@article{Raizada2008,
  author = {Raizada, Shikha and Sulzer, Michael P. and Tepley, Craig A. and Gonzalez, Sixto A. and Nicolls, Michael J.},
  title = {Inferring D region parameters using improved incoherent scatter radar techniques at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A12},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012882},
  doi = {10.1029/2007JA012882}
}
Roy A, Wen C-H, Doherty J and Mathews J (2008), "Signal Feature Extraction From Microbarograph Observations Using the Hilbert-Huang Transform", IEEE Transactions on Geoscience and Remote Sensing. Vol. 46(5), pp. 1442-1447.
Abstract: The Hilbert-Huang transform (HHT) is a relatively new time-frequency analysis tool. We present a new signal feature extraction technique based on HHT. This technique is used to extract diurnal and semidiurnal tides from atmospheric pressure data obtained from a microbarograph stationed at the Arecibo Observatory. Observation of seasonal variations of semidiurnal tides is possible due to the high precision offered by this technique. Furthermore, we apply the signal extraction procedure to isolate and remove high-amplitude disturbance signals from the time-series signal. This is demonstrated by extracting a hurricane event from the pressure data. The superior capabilities of the HHT-based technique to analyze time-varying signals compared to traditional linear techniques such as the wavelet transform and the fast Fourier transform are demonstrated.
BibTeX:
@article{Roy2008,
  author = {Roy, A. and Chun-Hsien Wen and Doherty, J.F. and Mathews, J.D.},
  title = {Signal Feature Extraction From Microbarograph Observations Using the Hilbert-Huang Transform},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  year = {2008},
  volume = {46},
  number = {5},
  pages = {1442-1447},
  doi = {10.1109/TGRS.2007.909916}
}
Seker I, Livneh DJ, Makela JJ and Mathews JD (2008), "Tracking F-region plasma depletion bands using GPS-TEC, incoherent scatter radar, and all-sky imaging at Arecibo", Earth Planets Space. Vol. 60, pp. 633-646.
Abstract: F-region plasma dynamics has been one of the main foci of the ionospheric research community for decades. The mid-latitude F-region has been considered to be relatively calm; however recent observations using highly sensitive CCD imaging systems and Global Positioning System (GPS) receivers have revealed that mid-latitude F-region mesoscale electrodynamics are more complex and this region is more active than usually assumed. Here we report combined incoherent scatter radar (ISR), imager, and GPS observations of F-region Medium-Scale Traveling Ionospheric Disturbance (MSTID) structures over the Arecibo Observatory in Puerto Rico. In particular, the plasma structures seen in the narrow-beam ISR cannot be understood fully without the all-sky images, which provide the context for the radar results—specifically, the spatial and temporal properties of the mesoscale structure. The GPS-derived total electron content (TEC) data provide additional information on the intensity of the MSTIDs. Here we present analysis of two specific plasma depletion events, which we prefer to call "MSTID bands". Important results on the 3D geometry of these structures were found using a newly developed observation technique. For the first time, it is shown that the southern part of MSTID bands reaches higher altitudes than the northern part (vertically tilted by 12° towards magnetic south). These results give a much broader perspective on nighttime, mid-latitude F-region structure and point to new ways of interpreting these structures and how they appear in ISR results.
BibTeX:
@article{Seker2008,
  author = {Ilgin Seker and Dorey J. Livneh and Jonathan J. Makela and John D. Mathews},
  title = {Tracking F-region plasma depletion bands using GPS-TEC, incoherent scatter radar, and all-sky imaging at Arecibo},
  journal = {Earth Planets Space},
  year = {2008},
  volume = {60},
  pages = {633-646}
}
Vondrak T, Plane JMC, Broadley S and Janches D (2008), "A chemical model of meteoric ablation", Atmospheric Chemistry and Physics. Vol. 8(23), pp. 7015-7031.
Abstract: Most of the extraterrestrial dust entering the Earth's atmosphere ablates to produce metal vapours, which have significant effects on the aeronomy of the upper mesosphere and lower thermosphere. A new Chemical Ablation Model (CAMOD) is described which treats the physics and chemistry of ablation, by including the following processes: sputtering by inelastic collisions with air molecules before the meteoroid melts; evaporation of atoms and oxides from the molten particle; diffusion-controlled migration of the volatile constituents (Na and K) through the molten particle; and impact ionization of the ablated fragments by hyperthermal collisions with air molecules. Evaporation is based on thermodynamic equilibrium in the molten meteoroid (treated as a melt of metal oxides), and between the particle and surrounding vapour phase. The loss rate of each element is then determined assuming Langmuir evaporation. CAMOD successfully predicts the meteor head echo appearance heights, observed from incoherent scatter radars, over a wide range of meteoroid velocities. The model also confirms that differential ablation explains common-volume lidar observations of K, Ca and Ca+ in fresh meteor trails. CAMOD is then used to calculate the injection rates into the atmosphere of a variety of elements as a function of altitude, integrated over the meteoroid mass and velocity distributions. The most abundant elements (Fe, Mg and Si) have peak injection rates around 85 km, with Na and K about 8 km higher. The more refractory element Ca ablates around 82 km with a Na:Ca ratio of 4:1, which does therefore not explain the depletion of atomic Ca to Na, by more than 2 orders of magnitude, in the upper mesosphere. Diffusion of the most volatile elements (Na and K) does not appear to be rate-limiting except in the fastest meteoroids. Non-thermal sputtering causes ~35% mass loss from the fastest (~60–70 km s?1) and smallest (10?17–10?13 g) meteoroids, but makes a minor contribution to the overall ablation rate.
BibTeX:
@article{Vondrak2008,
  author = {Vondrak, T. and Plane, J. M. C. and Broadley, S. and Janches, D.},
  title = {A chemical model of meteoric ablation},
  journal = {Atmospheric Chemistry and Physics},
  year = {2008},
  volume = {8},
  number = {23},
  pages = {7015-7031},
  doi = {10.5194/acp-8-7015-2008}
}
Waldrop LS, Kerr R and Richards P (2008), "Photoelectron impact excitation of OI 8446 A emission observed from Arecibo Observatory", Journal of Geophysical Research: Space Physics. Vol. 113(A1), pp. n/a-n/a.
Abstract: Photoelectron (PE) impact on thermospheric oxygen atoms is a major source of OI 8446 å emission excitation at midlatitudes. However, historical discrepancies between observed twilight emission brightnesses and PE model predictions have not only prompted speculation regarding secondary sources of excitation but also precluded the use of observed brightness as a much-needed diagnostic of thermospheric O density. In an effort to improve understanding of the physical mechanisms responsible for its excitation, this paper presents new photometric measurements of twilight OI 8446 å emission brightness, together with calculations using the Field Line Interhemispheric Plasma (FLIP) PE model, acquired from Arecibo Observatory under geomagnetically quiet conditions during three winter campaigns from 1999–2002. Winter is a particularly favorable season for twilight 8446 å observation in the northern hemisphere since significant PE production, and thus 8446 å excitation, persists for several hours in the fully illuminated, geomagnetic conjugate hemisphere in the absence of any local thermospheric illumination. The winter 8446 å brightness data are fully consistent with a dominant PE impact excitation source. However, the new data also confirm the Lancaster et al. (2000) report of excess early morning brightness at Arecibo with respect to PE models which use a tilted-dipole approximation to the geomagnetic field. By using the International Geomagnetic Reference Field (IGRF) geomagnetic field model to refine Arecibo's conjugate point location specified in the FLIP PE model, we demonstrate significantly improved agreement between the modeled and observed brightness decay profiles during both morning and evening twilight intervals.
BibTeX:
@article{Waldrop2008,
  author = {Waldrop, L. S. and Kerr, R. and Richards, P.},
  title = {Photoelectron impact excitation of OI 8446 A emission observed from Arecibo Observatory},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2008},
  volume = {113},
  number = {A1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012356},
  doi = {10.1029/2007JA012356}
}
Zarka P, Farrell W, Fischer G and Konovalenko A (2008), "Ground-Based and Space-Based Radio Observations ofá Planetary Lightning", Space Science Reviews. Vol. 137(1-4), pp. 257-269.
Abstract: We review radio detection of planetary lightning performed by Voyager, Galileo (including in-situ probe measurements), Cassini, and other spacecraft, and compare the information on the underlying physics derived from these observations—especially the discharge duration, at Jupiter and Saturn—with our knowledge of terrestrial lightning. The controversial evidence at Venus is discussed, as well as the prospects for lightning-like discharges in Martian dust-storms (and studies on terrestrial analogues). In addition, lightning sources provide radio beacons that allow us to probe planetary ionospheres. Ground-based observations of Saturn’s lightning have been attempted several times in the past and have been recently successful. They will be the subject of observations by the new generation of giant radio arrays. We review past results and future studies, focussing on the detection challenges and on the interest of ground-based radio monitoring, in conjunction with spacecraft observations or in standalone mode.
BibTeX:
@article{Zarka2008,
  author = {Zarka, P. and Farrell, W. and Fischer, G. and Konovalenko, A.},
  title = {Ground-Based and Space-Based Radio Observations ofá Planetary Lightning},
  journal = {Space Science Reviews},
  year = {2008},
  volume = {137},
  number = {1-4},
  pages = {257-269},
  url = {http://dx.doi.org/10.1007/s11214-008-9366-8},
  doi = {10.1007/s11214-008-9366-8}
}
Zhou Q, Raizada S, Tepley CA and Plane JM (2008), "Seasonal and diurnal variation of electron and iron concentrations at the meteor heights above Arecibo", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 70(1), pp. 49-60.
Abstract: We report observations of seasonal and local time variation of the averaged electron and iron concentrations, as well as simultaneous measurements of the two species, above the Arecibo Observatory (18.35°N, 66.75°N), Puerto Rico. The average Fe profile between 21:00 and 24:00 LT has a single peak at about 85 km with the exception of the summer when an additional peak exists at about 95 km. The higher Fe peak in the summer is correlated with higher electron concentrations in this season. The three nights of simultaneous measurements of electron and iron concentrations show that narrow layers of Fe and electrons are well correlated. Comparison of the climatological and simultaneous Fe and electron data suggests that recombination of Fe+ plays an important role in determining the Fe profile in the upper part of the Fe layer. Above 93 km, the Fe concentration appears to increase after sunset if the electron concentration exceeds about 4000 electrons cm?3. The average rate of Fe production is about 0.1 atom cm?3 s?1 for all seasons at 100 km in the early evening hours. A chemical model reveals that the concentration of Fe+ must be 50–80% of the total ionization over Arecibo for typical equinox conditions to explain the observed rate of Fe production. These high relative Fe+ concentrations are consistent with in situ observations that Fe+ is usually the dominant ion in sporadic E layers in the nighttime lower E region. This suggests that the source of Fe+ is provided by sporadic E layers descending over Arecibo after sunset. The Fe density between 80 and 85 km decreases during the night, for all seasons. This is attributed to the formation of stable molecular Fe species, such as FeOH, due to the increase in O3 and decrease in atomic O and H during the night at these altitudes.
BibTeX:
@article{Zhou2008,
  author = {Qihou Zhou and Shikha Raizada and Craig A. Tepley and John M.C. Plane},
  title = {Seasonal and diurnal variation of electron and iron concentrations at the meteor heights above Arecibo},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2008},
  volume = {70},
  number = {1},
  pages = {49-60},
  doi = {10.1016/j.jastp.2007.09.012}
}
Fentzke JT, Friedman JS and Janches D (2008), "High resolution potassium lidar meteor trail observations at Arecibo: Preliminary results.", In 25th International Laser Radar Conference.
BibTeX:
@conference{,
  author = {J. T. Fentzke and J. S. Friedman and D. Janches},
  title = {High resolution potassium lidar meteor trail observations at Arecibo: Preliminary results.},
  booktitle = {25th International Laser Radar Conference},
  year = {2008}
}
(2007), "Arecibo radar under pressure", Astronomy & Geophysics. Vol. 48(4), pp. 4.05. Blackwell Publishing Ltd.
Abstract: The planetary radar at Arecibo Observatory, the most powerful in the world, is short of money and may have to close.
BibTeX:
@article{AAG:AAG48404_5,,
  title = {Arecibo radar under pressure},
  journal = {Astronomy & Geophysics},
  publisher = {Blackwell Publishing Ltd},
  year = {2007},
  volume = {48},
  number = {4},
  pages = {4.05},
  url = {http://dx.doi.org/10.1111/j.1468-4004.2007.48404_5.x},
  doi = {10.1111/j.1468-4004.2007.48404_5.x}
}
Aponte N, Sulzer MP, Nicolls MJ, Nikoukar R and Gonzalez SA (2007), "Molecular ion composition measurements in the F1 region at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 112(A6), pp. n/a-n/a.
Abstract: The molecular ion composition in the F1 region is extremely difficult to measure with incoherent scatter (IS) radars because of the temperature/ion composition ambiguity in the shape of the incoherent scatter ion line spectrum. In practice, this means that a nonlinear least squares fitting (LSF) analysis of IS ion line data in this region can find different combinations of ionospheric parameters to be equally good fits. The only way to mitigate this problem is to add additional information to reduce the number of unknown parameters that need to be determined by the nonlinear least squares fitting. Following the concept originally reported by Waldteufel (1971), we have implemented a technique to combine the very precise electron density information in the plasma line with very accurate ion line spectra to measure the F1 region molecular ion composition. In this study, we describe the technique and show the first results from this method.
BibTeX:
@article{Aponte2007,
  author = {Aponte, Nestor and Sulzer, Michael P. and Nicolls, Michael J. and Nikoukar, Romina and Gonzalez, Sixto A.},
  title = {Molecular ion composition measurements in the F1 region at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JA012028},
  doi = {10.1029/2006JA012028}
}
Friedman JS and Chu X (2007), "Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35 N, 66.75 W): Seasonal variations", Journal of Geophysical Research: Atmospheres. Vol. 112(D14), pp. n/a-n/a.
Abstract: We present the mean seasonal climatology of the nocturnal temperature structure in the mesopause region (80–105 km) above the Arecibo Observatory, Puerto Rico (18.35°N, 66.75°W) from 106 nights of potassium Doppler lidar observations between December 2003 and September 2006. This first complete range-resolved mesopause climatology for a tropical latitude exhibits several unique features. Compared to higher latitude sites, mesospheric temperature inversion layers in the nocturnal means are much weaker at Arecibo. Seasonally large inversions occur in summer but are almost non-existent during the rest of the year. The Arecibo climatology shows a three-level mesopause: a high altitude in summer (~100 km), a medium altitude in late autumn and winter (~96 km), and a low altitude in early spring (~91 km). The mesopause is cold in the solstices (~171 K in summer, ~176 K in winter) and warm around equinoxes, particularly late autumn when it is near 195 K, while the spring mesopause temperature is close to 185 K. The lower thermosphere around 100 km at Arecibo shows a decreasing temperature from spring to summer when it reaches its coldest temperature, which is contrary to the increasing temperature observed at all midlatitude locations. Semiannual variations in the seasonal temperature have amplitudes as large as the annual variations through most of the MLT altitude range at Arecibo. These observed seasonal variations appear to be associated with the semi-annual oscillation, a predominantly tropical phenomenon. This report provides one of the very few observations of the semi-annual oscillation in lower thermosphere temperature.
BibTeX:
@article{Friedman2007,
  author = {Friedman, Jonathan S. and Chu, Xinzhao},
  title = {Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35 N, 66.75 W): Seasonal variations},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2007},
  volume = {112},
  number = {D14},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JD008220},
  doi = {10.1029/2006JD008220}
}
Goncharenko L, Foster J, Coster A, Huang C, Aponte N and Paxton L (2007), "Observations of a positive storm phase on September 10, 2005", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 69(10-11), pp. 1253-1272.
Abstract: In this study, we present multi-instrument observations of a strong positive phase of ionospheric storm, which occurred on September 10, 2005 during a moderate geomagnetic storm with minimum Dst=-60nT and maximum Kp=6-. The daytime electron density measured by the Millstone Hill incoherent scatter radar (42.6oN, 288.5oE) increased after 13UT (8LT) compared with that before the storm. This increase is observed throughout the daytime, lasts for about 9h, and covers F-region altitudes above ~230km. At the altitude of 300km, the maximum increase in Ne reaches a factor of 3 by 19:30-20:00UT and is accompanied by a ~1000K decrease in electron temperature, a ~100-150K increase in ion temperature, and a strong upward drift. Observations by Arecibo ISR (18.3oN, 293.3oE) reveal similar features, with the maximum increase in electron density reaching a factor of 2.5 at 21:30UT, i.e. 1.5-2h later than over Millstone Hill. The GPS TEC data show that the increase in electron density observed at Millstone Hill and Arecibo is only a part of a global picture reflected in TEC. The increase in TEC reaches a factor of 2 and covers middle and low latitudes at 19UT. At later times this increase moves to lower latitudes. A combination of mechanisms were involved in generation of positive phase. The penetration electric field resulted in Ne enhancements at subauroral and middle latitudes, the TAD/TID played an important role at middle and lower latitudes, and increase in O/N2 ratio could contribute to the observed positive phase at middle and lower latitudes. The results show the importance of an upward vertical drift at ~140-250km altitude, which is observed for sustained period of time and assists in the convergence of ionization into the F-region.
BibTeX:
@article{Goncharenko2007,
  author = {L.P. Goncharenko and J.C. Foster and A.J. Coster and C. Huang and N. Aponte and L.J. Paxton},
  title = {Observations of a positive storm phase on September 10, 2005},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2007},
  volume = {69},
  number = {10-11},
  pages = {1253-1272},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682607000727},
  doi = {10.1016/j.jastp.2006.09.011}
}
Rodrigues FS, Nicolls MJ, Woodman R, Hysell DL, Chau JL and GonzÀlez SA (2007), "Ion gyroresonance observations at Jicamarca revisited", Geophysical Research Letters. Vol. 34(13), pp. n/a-n/a.
Abstract: This paper presents recent observations of the proton gyroresonance over Jicamarca. In October 2006, a single-polarization double-pulse experiment was set up to measure the first gyroresonance peak in the incoherent scatter (IS) auto-correlation function (ACF). Despite the clutter caused by Spread-F and artificial satellites, it was possible to measure the first proton gyroresonance peak of the ACF in the topside ionosphere. For the first time, least-squares fits of theoretical IS ACFs to gyroresonance measurements are reported. Theoretical ACFs that best fit the measurements were found using the H+ fraction and temperature (assuming Te = Ti) as fitting parameters. Uncertainties for the estimated fraction of H+ were as low as 12%, while uncertainties for estimated temperatures were around 30%. These are the first successful gyroresonance measurements since the early observations of Farley (1967), and it is the first time measurements of this type have been used to obtain least squares estimates of ion composition and temperatures.
BibTeX:
@article{GRL:GRL23052,
  author = {Rodrigues, F. S. and Nicolls, M. J. and Woodman, R. and Hysell, D. L. and Chau, J. L. and GonzÀlez, S. A.},
  title = {Ion gyroresonance observations at Jicamarca revisited},
  journal = {Geophysical Research Letters},
  year = {2007},
  volume = {34},
  number = {13},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2007GL029680},
  doi = {10.1029/2007GL029680}
}
Janches D and Nicolls MJ (2007), "Diurnal variability of the gyro resonance line observed with the Arecibo incoherent scatter radar at E- and F1-region altitudes", Geophysical Research Letters. Vol. 34(1), pp. n/a-n/a.
Abstract: In this paper, we report on observations of the diurnal variation of a resonance line that occurs near the gyro frequency as seen with the incoherent scatter radar (ISR) at the Arecibo Observatory. This gyro resonance line has rarely been observed in ISR data, but recent results, exemplified by the observations of Bhatt et al. (2006), have implied that the gyro line is a common ionospheric feature. The observations presented here were made with much better altitude resolution in comparison with previous results and represent full 24 hour coverage for several days. The data indicate that an increase in the gyro line intensity near sunrise and sunset is an everyday occurrence. As the increase in intensity is occurring at sunset, the gyro line frequency drops from the expected frequency to one near zero frequency. As the increase in intensity is occurring at sunrise, the gyro line frequency increases from near zero frequency to one near the expected gyro line frequency. This behavior of the gyro line frequency and intensity has not been observed before. We explain these results using normal Maxwellian incoherent scatter theory together with the diurnal variation of the density in the E and F1 regions. These results may explain previous observations of the gyro line made at Arecibo and suggest avenues of future research for studying this exciting feature of the incoherent scatter spectrum.
BibTeX:
@article{Janches2007,
  author = {Janches, Diego and Nicolls, Michael J.},
  title = {Diurnal variability of the gyro resonance line observed with the Arecibo incoherent scatter radar at E- and F1-region altitudes},
  journal = {Geophysical Research Letters},
  year = {2007},
  volume = {34},
  number = {1},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006GL028510},
  doi = {10.1029/2006GL028510}
}
Kohenl T, Aponte N, Nicolls MJ, Robles E, Tepley CA and Gonzalez SA (2007), "A Comparison of Long-term Meridional Neutral Winds extracted from Arecibo Incoherent Scatter Radar with the Neutral Winds Obtained via Fabry Perot Interferometry", In Radar Conference, 2007 IEEE. , pp. 259-264.
Abstract: This ten-week summer study compares long term averages of the meridional (north-south) component of neutral winds obtained by Arecibo 630 nm Fabry Perot interferometry (FPI), with those obtained by the Arecibo incoherent scatter radar (ISR). Night-time meridional neutral winds from the ISR were plotted by year and by month for the period between 1985 and 2003, and compared to the plots produced by Robles et al [1], who investigated FPI derived neutral winds. The magnitude and trends of the ISR data fit well with the FPI study, indicating that the neutral wind vector rotated from southeast to due east mostly due to changes in the meridional (north-south) component. A shift in the vector over time is important for modeling the ionosphere, since neutral winds are one of three main forces in the F-region of the ionosphere (region of atmosphere starting at 150 km above the earth's surface) that drive the movement of plasma. The ionosphere is the primary medium of much RF communication, and modeling plasma movement assists in mitigating unwanted propagation effects.
BibTeX:
@conference{Kohenl2007,
  author = {Talia Kohenl and Nestor Aponte and Michael J. Nicolls and Eva Robles and Craig A. Tepley and Sixto A. Gonzalez},
  title = {A Comparison of Long-term Meridional Neutral Winds extracted from Arecibo Incoherent Scatter Radar with the Neutral Winds Obtained via Fabry Perot Interferometry},
  booktitle = {Radar Conference, 2007 IEEE},
  year = {2007},
  pages = {259-264},
  doi = {10.1109/RADAR.2007.374224}
}
Labno A, Pradipta R, Lee MC, Sulzer MP, Burton LM, Cohen JA, Kuo SP and Rokusek DL (2007), "Whistler-mode wave interactions with ionospheric plasmas over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 112(A3), pp. n/a-n/a.
Abstract: The Naval transmitter, code-named NAU, in Puerto Rico emits radio waves at a power and frequency of 100 kW and 40.75 kHz, respectively. The NAU-generated 40.75 kHz whistler-mode waves are intense enough to excite lower hybrid waves and zero-frequency field-aligned ionospheric irregularities over Arecibo. It is proposed that NAU is responsible for causing the enhanced plasma lines, detected by the Arecibo 430 MHz radar in the nighttime ionosphere F region, in the presence of spread F events. The lower hybrid waves, generated in a broad range of altitudes at the wake of 40.75 kHz whistler-mode waves, have a single frequency of 40.75 kHz but with a spectrum of wavelengths. They can effectively accelerate electrons continuously along the Earth's magnetic field with energies from a fraction of 1 eV to 10 eV. These energetic streaming electrons, when detected by the Arecibo 430 MHz radar, give rise to enhanced plasma lines with a frequency spectrum of ?3.25–4.75 MHz.
BibTeX:
@article{Labno2007,
  author = {Labno, A. and Pradipta, R. and Lee, M. C. and Sulzer, M. P. and Burton, L. M. and Cohen, J. A. and Kuo, S. P. and Rokusek, D. L.},
  title = {Whistler-mode wave interactions with ionospheric plasmas over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A3},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JA012089},
  doi = {10.1029/2006JA012089}
}
Larsen MF, Hysell DL, Zhou QH, Smith SM, Friedman J and Bishop RL (2007), "Imaging coherent scatter radar, incoherent scatter radar, and optical observations of quasiperiodic structures associated with sporadic E layers", Journal of Geophysical Research: Space Physics. Vol. 112(A6), pp. n/a-n/a.
Abstract: During June and July 2002, a 30-MHz imaging coherent scatter radar was installed and operated on the island of St. Croix, to view the E region ionosphere above Arecibo, Puerto Rico. During the observing period, 10 events with discernible quasiperiodic echo structure were observed with the coherent scatter radar. In six of those events, simultaneous measurements were made with the Arecibo 430-MHz incoherent scatter radar. The imaging coherent scatter radar allows us to locate and track the echo structures within the volume illuminated by the transmitter, which shows structures that are generally aligned along wavefronts. A slight preference for motion of the structures toward the southwest is evident throughout the period, but the propagation directions and speeds vary greatly. The incoherent scatter radar measurements show a close correspondence between the occurrence of the coherent echoes and the location of the enhanced electron density structures. In particular, the coherent echoes occur when the electron density layers show uplifts.
BibTeX:
@article{Larsen2007,
  author = {Larsen, M. F. and Hysell, D. L. and Zhou, Q. H. and Smith, S. M. and Friedman, J. and Bishop, R. L.},
  title = {Imaging coherent scatter radar, incoherent scatter radar, and optical observations of quasiperiodic structures associated with sporadic E layers},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JA012051},
  doi = {10.1029/2006JA012051}
}
Lei J, Roble RG, Wang W, Emery BA and Zhang S-R (2007), "Electron temperature climatology at Millstone Hill and Arecibo", Journal of Geophysical Research: Space Physics. Vol. 112(A2), pp. n/a-n/a.
Abstract: In this paper, ionospheric electron temperature (Te) data for more than two solar cycles measured by the incoherent scatter radars (ISR) at Millstone Hill (42.6°N, 71.5°W) and Arecibo (18.3°N, 66.7°W) are compared with the theoretical Te calculated from the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (NCAR-TIEGCM) to investigate the temporal variations of Te. The comparisons are made for both low and high solar activity conditions and for three seasons: equinox, summer, and winter. The observations show that the diurnal variation of Te is characterized by morning and evening peaks at Arecibo and by a morning peak at Millstone Hill. The occurrence and strength of the peaks at Arecibo are significantly different from those at Millstone Hill. Daytime Te tends to increase with solar activity at both stations below ?300 km. Te above 300 km generally decreases with solar activity; however, it increases with solar activity in equinox and summer at Arecibo, whereas it does so only in summer at Millstone Hill. The TIEGCM model can reproduce these variations. However, the modeled evening peak is weaker than that from observations at Arecibo. The simulations show that the daytime bulge of Te tends to occur at low latitudes and high solar activity, as seen in the observations, and the significant morning peak at low solar activity over Arecibo is associated with the equatorial anomaly. Moreover, an interesting feature predicted by the model is that the midday Te at the F2 peak height increases with solar activity when F10.7 values are less than about 100 â 10?22 W m?2 Hz?1 or larger than 190 â 10?22 W m?2 Hz?1 at Millstone Hill; so does at Arecibo when F10.7 values are larger than 100 â 10?22 W m?2 Hz?1. As a result, a positive correlation between daytime Te and Ne occurs under these conditions.
BibTeX:
@article{Lei2007,
  author = {Lei, Jiuhou and Roble, Raymond G. and Wang, Wenbin and Emery, Barbara A. and Zhang, Shun-Rong},
  title = {Electron temperature climatology at Millstone Hill and Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A2},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JA012041},
  doi = {10.1029/2006JA012041}
}
Liu L, Le H, Wan W, Sulzer MP, Lei J and Zhang M-L (2007), "An analysis of the scale heights in the lower topside ionosphere based on the Arecibo incoherent scatter radar measurements", Journal of Geophysical Research: Space Physics. Vol. 112(A6), pp. n/a-n/a.
Abstract: We statistically analyze the ionospheric scale heights in the lower topside ionosphere based on the electron density (Ne) and temperature profiles observed from the incoherent scatter radar (ISR) at Arecibo (293.2°E, 18.3°N), Puerto Rico. In this study, a database containing the Arecibo ISR observations from 1966 to 2002 has been used in order to investigate the diurnal and seasonal variations and solar activity dependences of the vertical scale height (VSH), which is deduced from the electron concentration profiles defined as the value of -dh/d(ln(Ne)), and the effective scale height (Hm), which is defined as the scale height in the Chapman-alpha function to approximate the Ne profiles. As a measure of the slope of the height profiles of the topside electron density, the derived VSH and Hm show marked diurnal and seasonal variations and solar activity dependences. Their features are discussed in terms of thermal structures in the lower topside ionosphere. We also investigate the quantitative relationships between Hm, VSH, and plasma scale height (Hp) over Arecibo. The similarities and differences in these scale heights are discussed. Results suggest that both the contributions from topside temperature structure and diffusion processes can also greatly control VSH and Hm through changing the profile shape.
BibTeX:
@article{Liu2007,
  author = {Liu, Libo and Le, Huijun and Wan, Weixing and Sulzer, Mike P. and Lei, Jiuhou and Zhang, Man-Lian},
  title = {An analysis of the scale heights in the lower topside ionosphere based on the Arecibo incoherent scatter radar measurements},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012250},
  doi = {10.1029/2007JA012250}
}
Liu L, Wan W, Zhang M-L, Ning B, Zhang S-R and Holt JM (2007), "Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment", Annales Geophysicae. Vol. 25(9), pp. 2019-2027.
BibTeX:
@article{Liu2007a,
  author = {Liu, L. and Wan, W. and Zhang, M.-L. and Ning, B. and Zhang, S.-R. and Holt, J. M.},
  title = {Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment},
  journal = {Annales Geophysicae},
  year = {2007},
  volume = {25},
  number = {9},
  pages = {2019-2027},
  doi = {10.5194/angeo-25-2019-2007}
}
Liu L, Wan W, Yue X, Zhao B, Ning B and Zhang M-L (2007), "The dependence of plasma density in the topside ionosphere on the solar activity level", Annales Geophysicae. Vol. 25(6), pp. 1337-1343.
BibTeX:
@article{Liu2007b,
  author = {Liu, L. and Wan, W. and Yue, X. and Zhao, B. and Ning, B. and Zhang, M.-L.},
  title = {The dependence of plasma density in the topside ionosphere on the solar activity level},
  journal = {Annales Geophysicae},
  year = {2007},
  volume = {25},
  number = {6},
  pages = {1337-1343},
  doi = {10.5194/angeo-25-1337-2007}
}
Livneh DJ, Seker I, Djuth FT and Mathews JD (2007), "Continuous quasiperiodic thermospheric waves over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 112(A7), pp. n/a-n/a.
Abstract: Incoherent scatter radar (ISR) power profile observations at Arecibo Observatory (AO) have revealed long vertical wavelength (>100 km) quasi-coherent waves with periods of ?1 hour that are observed to be nearly continuously present over two ?35-hour geomagnetically quiet observation periods. When properly filtered, results from both 22–23 March 2004 and 5–6 June 2005 provide unambiguous views of these waves. The waves are strong throughout the F region, often spanning 160 to above 500 km in altitude and are present day and night in the F2 layer. Filtering techniques that were used to better reveal the waves are extensively discussed. Barometric pressure and imager data, both of which were taken on site at Arecibo, are used to provide further insight into the nature of these waves. These waves may be linked to high-latitude medium-scale traveling ionospheric disturbances (MSTIDs) observed with the superDARN radar network and associated with E region auroral electrojet source(s) that are quasi-coherent under geomagnetic quiet conditions. As auroral-zone MSTIDs are believed to dissipate before reaching Arecibo latitudes (Vadas, 2007), various alternative sources including weather patterns are explored.
BibTeX:
@article{Livneh2007,
  author = {Livneh, D. J. and Seker, I. and Djuth, F. T. and Mathews, J. D.},
  title = {Continuous quasiperiodic thermospheric waves over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A7},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006JA012225},
  doi = {10.1029/2006JA012225}
}
Martinis C and Mendillo M (2007), "Equatorial spread F-related airglow depletions at Arecibo and conjugate observations", Journal of Geophysical Research: Space Physics. Vol. 112(A10), pp. n/a-n/a.
Abstract: We present evidence of the incursion into the Caribbean region of airglow depletions associated with the equatorial Rayleigh-Taylor instability. Data from the Boston University all-sky imager located at Arecibo, Puerto Rico (18.3°N, 66.7°W, 28°N magnetic latitude), have been used to identify several nights with 630.0 nm airglow patterns that are typical signatures of equatorial spread F and distinctly different from the more common “airglow bands” frequently observed there. Two case studies (2 November 2002 and 26 February 2003) show the occurrence of simultaneous airglow depletions observed with another all-sky imager located at El Leoncito, Argentina (31.8°S, 69.3°W, 18°S magnetic latitude), relatively close to the Arecibo conjugate point. Supporting information is obtained from Defense Meteorological Satellite Program, ROCSAT-1, and GPS data, all of them showing the presence of strong ionospheric irregularities collocated with the airglow depletions. Mapping the circular field of view from Arecibo into the Southern Hemisphere reveals a distorted pattern due to the differences in the magnetic field characteristics in both hemispheres. This adds an interesting spatial complexity to the formulation of conjugate point observing programs in the Latin American longitude sector.
BibTeX:
@article{Martinis2007,
  author = {Martinis, C. and Mendillo, M.},
  title = {Equatorial spread F-related airglow depletions at Arecibo and conjugate observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2007},
  volume = {112},
  number = {A10},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007JA012403},
  doi = {10.1029/2007JA012403}
}
Pradipta R, Labno A, Lee MC, Burke WJ, Sulzer MP, Cohen JA, Burton LM, Kuo SP and Rokusek DL (2007), "Electron precipitation from the inner radiation belt above Arecibo", Geophysical Research Letters. Vol. 34(8), pp. n/a-n/a.
Abstract: We examine possible correlations between occurrences of nighttime E-region plasma line (PL) enhancements over Arecibo and 40.75 kHz NAU emissions. On the night of January 1–2, 2006, the experiments were conducted from 22:00 to 6:00 local time (LT). NAU transmitter was initially turned off until 01:45 LT, when continuous operations resumed for the remainder of the experiments. Enhanced PL events lasting <10 s had central frequencies and bandwidths of about 2.5 and 1.5 MHz, respectively, indicating that Arecibo radar detected 2.3 to 8.5 eV suprathermal electrons streaming along geomagnetic fields. The rate of PL event detections increased by a factor of 2.8 after NAU turn-on. We suggest that 40.75 kHz radiation sporadically leaked though local ionosphere, probably abetted by field-aligned irregularities. The radiation propagated in whistler mode into the L = 1.35 inner radiation belt where gyroresonant interactions with trapped 390 keV electrons increased the precipitation rate.
BibTeX:
@article{Pradipta2007,
  author = {Pradipta, R. and Labno, A. and Lee, M. C. and Burke, W. J. and Sulzer, M. P. and Cohen, J. A. and Burton, L. M. and Kuo, S. P. and Rokusek, D. L.},
  title = {Electron precipitation from the inner radiation belt above Arecibo},
  journal = {Geophysical Research Letters},
  year = {2007},
  volume = {34},
  number = {8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007GL029807},
  doi = {10.1029/2007GL029807}
}
Raizada S, Rapp M, Lubken F-J, Hoffner J, Zecha M and Plane JMC (2007), "Effect of ice particles on the mesospheric potassium layer at Spitsbergen (78 N)", Journal of Geophysical Research: Atmospheres. Vol. 112(D8), pp. n/a-n/a.
Abstract: This paper quantitatively evaluates the influence of ice particles on the K layer by using radar and lidar measurements. The methodology involves determination of the volumetric surface area [Aice] of the ice particles in a noctilucent cloud by combining a microphysical ice particle model with a charging model to produce an empirical proxy for polar mesosphere summer echoes (PMSE) based on the properties of the charged aerosol particles. The altitudinal variation of [Aice] reveals peak values of about 2.2 â 10-8 cm-1 around 85 km. The first-order loss rate of atomic K due to uptake on the ice particles maximizes close to 2.2 â 10-4 s-1 at 85 km. To examine the variability of [Aice] on background parameters, a sensitivity study showed that a ±10% variation in [Aice] can result from either a ±5 K shift in the temperatures relative to a background profile or from a ±30% change in the water vapor concentration. We found that the peak [Aice] remains constant for a change of +4 to –6 K temperature fluctuations over the altitude range of 83–85 km. Finally, a new atmospheric model of potassium predicts profiles of the K layer in early May and July that are in good agreement with the observations, when the seasonally averaged K ablation flux at 79°N is set to 160 atom cm-2 s-1. This study reveals that both the vertical wind and ice particles play a significant role in controlling the K layer distribution at high latitudes.
BibTeX:
@article{Raizada2007,
  author = {Raizada, Shikha and Rapp, Markus and Lubken, F.-J. and Hoffner, J. and Zecha, M. and Plane, J. M. C.},
  title = {Effect of ice particles on the mesospheric potassium layer at Spitsbergen (78 N)},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2007},
  volume = {112},
  number = {D8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JD006938},
  doi = {10.1029/2005JD006938}
}
Seker I, Mathews JD, Wiig J, Gutierrez PF, Friedman JS and Tepley CA (2007), "First results from the Penn State Allsky Imager at the Arecibo Observatory", Earth Planets Space. Vol. 59, pp. 165-176.
Abstract: The Penn State Allsky imager (PSASI), a user-owned-public-access (UOPA) instrument installed at Arecibo Observatory (AO: 18.3°N, 66.75°W; altitude: 350 m a.s.l.; L = 1.43 at 300 km; dip angle: 46°; geomagnetic coordinates: 29°N, 5.5°E), is a CCD-based high-resolution allsky optical imager that has been collecting ionospheric airglow data at night since May 2003. The computer controlled six-position filter wheel is equipped with three filters at 630 nm (red), 557.7 nm (green), and 777.4 nm (near-IR), respectively, which correspond to ionosphere-related oxygen emissions. The imager data, taken for more than 3.5 years now, is being used to study various ionospheric processes, such as mapped equatorial spread-F plumes, E-region gravity waves, among other, in conjunction with the AO incoherent scatter radar (ISR), mesosphere and lower thermosphere (MLT) metals lidar, and other instruments, including microbarographs. Data availability and quality as well as specific airglow events on both small/large time/spatial scales are examined, categorized, and made freely available at a data-server website. Our goal here is to briefly review the airglow science enabled by allsky imaging at AO, to describe the instrument and the data-collection methodology, and to present some of the significant results, including airglow events that correspond to ISR results.
BibTeX:
@article{Seker2007,
  author = {Ilgin Seker and John D. Mathews and Johannes Wiig and Paloma F. Gutierrez and Jonathan S. Friedman and Craig A. Tepley},
  title = {First results from the Penn State Allsky Imager at the Arecibo Observatory},
  journal = {Earth Planets Space},
  year = {2007},
  volume = {59},
  pages = {165-176},
  url = {http://adsabs.harvard.edu/abs/2007EP%26S...59..165S}
}
Strelnikova I, Rapp M, Raizada S and Sulzer M (2007), "Meteor smoke particle properties derived from Arecibo incoherent scatter radar observations", Geophysical Research Letters. Vol. 34(15), pp. n/a-n/a.
Abstract: We present a new algorithm to infer information on the properties of charged meteoric smoke particles (MSPs) from the shape of incoherent scatter radar spectra. We show that in the presence of charged MSPs the spectrum can be approximated as the sum of two Lorentzians. These two distinct spectral lines correspond to two diffusion modes in the D-region plasma, i.e., one due the presence of positive ions and one because of heavy charged MSPs. The widths and amplitudes of these two spectral lines yield information on the radius and number density (the latter only for positively charged particles) of the charged MSPs. We apply this new algorithm to measurements obtained with the 430 MHz ISR at Arecibo and demonstrate that the observed spectra indeed bear the features anticipated in the presence of charged MSPs. Resulting values of retrieved MSP number densities and radii fall well within the range of values expected from models and independent in situ observations.
BibTeX:
@article{Strelnikova2007,
  author = {Strelnikova, Irina and Rapp, Markus and Raizada, Shikha and Sulzer, Mike},
  title = {Meteor smoke particle properties derived from Arecibo incoherent scatter radar observations},
  journal = {Geophysical Research Letters},
  year = {2007},
  volume = {34},
  number = {15},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2007GL030635},
  doi = {10.1029/2007GL030635}
}
Wen C-H, Briczinski S, Livneh D, Doherty J and Mathews J (2007), "Pulse-level interference and meteor processing of Arecibo ISR data", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 69(9), pp. 973-980.
BibTeX:
@article{Wen2007,
  author = {C.-H. Wen and S.J. Briczinski and D.J. Livneh and J.F. Doherty and J.D. Mathews},
  title = {Pulse-level interference and meteor processing of Arecibo ISR data},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2007},
  volume = {69},
  number = {9},
  pages = {973-980},
  doi = {10.1016/j.jastp.2007.03.004}
}
Zhang S-R, Holt JM, Bilitza DK, van Eyken T, McCready M, Amory-Mazaudier C, Fukao S and Sulzer M (2007), "Multiple-site comparisons between models of incoherent scatter radar and IRI", Advances in Space Research . Vol. 39(5), pp. 910-917.
Abstract: Long-term databases of multiple incoherent scatter radars (ISRs) are used to create local empirical models at seven ISR sites including, from magnetic north to south and east to west, EISCAT Svalbard Radar (Norway), Sondrestrom Radar (Greenland), EISCAT TromsÜRadars (Norway), Millstone Hill Radar (USA), St. Santin Radar (France), Shigaraki Middle and Upper atmosphere (MU) Radar (Japan) and Arecibo Radar (Puerto Rico). As local models, they can represent some features that may be smeared out in a global model, and are important complements to and validation tools for global models such as IRI. This paper presents comparisons between these ISR models and IRI for median solar activity and quiet magnetic activity conditions, with focus on daytime height variations for electron density, ion and electron temperatures.
BibTeX:
@article{Zhang2007,
  author = {Shun-Rong Zhang and John M. Holt and Dieter K. Bilitza and Tony van Eyken and Mary McCready and Christine Amory-Mazaudier and Shoichiro Fukao and Michael Sulzer},
  title = {Multiple-site comparisons between models of incoherent scatter radar and IRI},
  journal = {Advances in Space Research },
  year = {2007},
  volume = {39},
  number = {5},
  pages = {910-917},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117706004364},
  doi = {10.1016/j.asr.2006.05.027}
}
Abdu M, Ramkumar T, Batista I, Brum C, Takahashi H, Reinisch B and Sobral J (2006), "Planetary wave signatures in the equatorial atmosphere-ionosphere system, and mesosphere- E- and F-region coupling", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 68(3-5), pp. 509-522.
Abstract: Upward transport of wave energy and momentum due to gravity, tidal and planetary waves from below and extra-tropics controls the phenomenology of the equatorial atmosphere–ionosphere system. An important aspect of this phenomenology is the development of small- and large-scale structures including thin layers in the mesosphere and E-region, and the formation of wide spectrum plasma structures of the equatorial F-region, widely known as equatorial spread F/plasma bubble irregularities (that are known to have significant impact on space application systems based on trans-ionospheric radio waves propagation). It seems that the effects of tidal and gravity waves at mesospheric and thermospheric heights and their control of ionospheric densities, electric fields and currents are relatively better known than are the effects originating from vertical coupling due to planetary waves. Results from airglow, radar and ionospheric sounding observations demonstrate the existence of significant planetary wave influence on plasma parameters at E- and F-region heights over equatorial latitudes. We present and discuss here some results showing planetary wave oscillations in concurrent mesospheric winds and equatorial electrojet intensity variations in the Indian sector as well as in the mesospheric airglow and F-layer height variation in Brazil. Also presented are evidences of planetary wave-scale oscillations in equatorial evening pre-reversal electric field (F-region vertical drift) and their effects on equatorial spread F /plasma bubble irregularity development and day-to-day variability.
BibTeX:
@article{Abdu2006,
  author = {M.A. Abdu and T.K. Ramkumar and I.S. Batista and C.G.M. Brum and H. Takahashi and B.W. Reinisch and J.H.A. Sobral},
  title = {Planetary wave signatures in the equatorial atmosphere-ionosphere system, and mesosphere- E- and F-region coupling},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2006},
  volume = {68},
  number = {3-5},
  pages = {509-522},
  note = {Vertical Coupling in the Atmosphere/Ionosphere System 2nd IAGA/ICMA Workshop on Vertical Coupling in the Atmosphere/Ionosphere System, Bath, UK, 12 - 15 July, 2004 },
  url = {http://www.sciencedirect.com/science/article/pii/S1364682605002592},
  doi = {10.1016/j.jastp.2005.03.019}
}
Abdu MA, Batista PP, Batista IS, Brum CGM, Carrasco AJ and Reinisch BW (2006), "Planetary wave oscillations in mesospheric winds, equatorial evening prereversal electric field and spread F", Geophysical Research Letters. Vol. 33(7), pp. L07107 (4 pages).
Abstract: Analysis of the MLT region winds measured by a meteor radar and the evening F region vertical plasma drift (prereversal zonal electric field -PRE) measured by digisondes over low latitude sites in Brazil, provide evidence of planetary wave (PW) scale oscillations of episodic nature simultaneously at mesospheric and F region heights. 4-day and 7-day periods are found to dominate the event analyzed. The PW scale oscillations in the PRE produces strong modulation in the equatorial spread F (ESF) irregularity processes as diagnosed by the digisondes. Considerations on the PRE development mechanism involving the E layer integrated conductivity including the effect of metallic ions and tidal winds point to the source of the PRE oscillations to be PW modulation of E region tidal winds. The PW oscillations in PRE appear to be an important source of the day-to-day variability in the ESF.
BibTeX:
@article{Abdu2006a,
  author = {Abdu, M. A. and Batista, P. P. and Batista, I. S. and Brum, C. G. M. and Carrasco, A. J. and Reinisch, B. W.},
  title = {Planetary wave oscillations in mesospheric winds, equatorial evening prereversal electric field and spread F},
  journal = {Geophysical Research Letters},
  year = {2006},
  volume = {33},
  number = {7},
  pages = {L07107 (4 pages)},
  url = {http://dx.doi.org/10.1029/2005GL024837},
  doi = {10.1029/2005GL024837}
}
Bhatt AN, Gerken Kendall EA, Kelley MC, Sulzer MP and Shume EB (2006), "Observations of strong gyro line spectra at Arecibo near dawn", Geophysical Research Letters. Vol. 33(14), pp. n/a-n/a.
Abstract: Experiments performed near dawn during the PARS Summer School at Arecibo in August 2004 show clear evidence of the gyro line in the incoherent scatter radar (ISR) spectra with only six minutes of signal integration. A very weak gyro line was first observed by Behnke and Hagen (1978) requiring two hours of signal integration. Electrons that resonate with the gyro wave mode are well within the thermal distribution. At this point we know of no theory to explain the magnitude of the gyro lines we have detected although it seems clear that the presence of photoelectrons is related to it. We present the experimental results and a comparison with an incoherent scatter numerical model based on the theory developed by Trulsen and BjÜrn (1978), which shows a very good correlation. From this comparison, and by combining the gyro line and the plasma line techniques, it is possible to make electron temperature measurements.
BibTeX:
@article{Bhatt2006,
  author = {Bhatt, A. N. and Gerken Kendall, E. A. and Kelley, M. C. and Sulzer, M. P. and Shume, E. B.},
  title = {Observations of strong gyro line spectra at Arecibo near dawn},
  journal = {Geophysical Research Letters},
  year = {2006},
  volume = {33},
  number = {14},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006GL026139},
  doi = {10.1029/2006GL026139}
}
Bishop RL, Aponte N, Earle GD, Sulzer M, Larsen MF and Peng GS (2006), "Arecibo observations of ionospheric perturbations associated with the passage of Tropical Storm Odette", Journal of Geophysical Research: Space Physics. Vol. 111(A11), pp. A11320 (9 pages).
Abstract: A suite of instruments including incoherent scatter radar, ionosonde, and a satellite-bourne GPS receiver observed the ionosphere immediately following the passage of a tropical storm. Tropical Storm Odette formed on 4 December 2003 and proceeded northeasterly over the next 4 days, passing within 600 km of the Arecibo Observatory (AO). On the night of 7–8 December AO measured F region plasma densities and velocities nearly coincident with the storm. Large velocity variations, 10–80 m/s, are evident in the plasma drift components. The variations appear wave-like with an average period of 90 min at 367 km. Zonal drifts were observed with magnitudes significantly greater than commonly observed for similar geomagnetic conditions. The Ramey ionosonde observed intense midlatitude spread F on the night following the closest passage of the storm. GPS occultations within the storm path showed an increase in gravity wave activity and F region scintillation. Combining the local increase in gravity wave activity with the large drift variations and dominant meridional electric field observed immediately following the storm's traversal of the flux tube coincident with the AO observing volume provide insight into coupling between mesoscale weather systems and the ionosphere.
BibTeX:
@article{Bishop2006,
  author = {Bishop, R. L. and Aponte, N. and Earle, G. D. and Sulzer, M. and Larsen, M. F. and Peng, G. S.},
  title = {Arecibo observations of ionospheric perturbations associated with the passage of Tropical Storm Odette},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A11},
  pages = {A11320 (9 pages)},
  url = {http://dx.doi.org/10.1029/2006JA011668},
  doi = {10.1029/2006JA011668}
}
Brum C, Abdu M, Batista I, Carrasco A and Terra P (2006), "Numerical simulation of nighttime electron precipitation in the lower ionosphere over a sub-auroral region ", Advances in Space Research . Vol. 37(5), pp. 1051-1057.
Abstract: This work presents computational simulations of electron precipitation events in the lower ionosphere to explain 30MHz riometer absorption events registered at the Brazilian Antarctic Station - BAS (62.56S; 58.39W). The simulations are based on the calculation of ion production rates from different sources (interplanetary and geocoronal ultraviolet radiations, energetic electrons and cosmic rays) and the use of a detailed ion chemical scheme to obtain the electron density which is then used to calculate the absorption at 30MHz. The electron density calculations were performed using the continuity equations for 25 positive ions and 10 negative ions, involving 175 chemical reactions, that are solved under chemical equilibrium condition. The simulation results show that a flux of about 2.5x1e6 electrons/cm-2/s-1 can increase the ionospheric cosmic noise absorption by 1 dB. The results also show that the amplitude of the maximum absorption is sensitive to variations in the precipitated electron flux in the energy range of 98-320 keV that affect most the height region of 65-85km, and that a larger contribution of the ionospheric absorption due to electron precipitation arising from above the height of absorption peak (rather than from below it), that is, the lower energy range of the precipitated electron spectra has a more dominant contribution to the attenuation of the galactic cosmic noise signal.
BibTeX:
@article{Brum2006,
  author = {C.G.M. Brum and M.A. Abdu and I.S. Batista and A.J. Carrasco and P.M. Terra},
  title = {Numerical simulation of nighttime electron precipitation in the lower ionosphere over a sub-auroral region },
  journal = {Advances in Space Research },
  year = {2006},
  volume = {37},
  number = {5},
  pages = {1051-1057},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117706000342},
  doi = {10.1016/j.asr.2006.02.003}
}
Cerruti AP, Kintner PM, Gary DE, Lanzerotti LJ, de Paula ER and Vo HB (2006), "Observed solar radio burst effects on GPS/Wide Area Augmentation System carrier-to-noise ratio", Space Weather. Vol. 4(10), pp. n/a-n/a.
Abstract: The first direct observations of Global Positioning System (GPS) L1 (1.57542 GHz) carrier-to-noise ratio degradation due to a solar radio burst are presented for an event that occurred on 7 September 2005. Concurrent carrier-to-noise ratio data from GPS satellites are available from receivers at Arecibo Observatory, Puerto Rico; San Juan, Puerto Rico; and also from Anderson, South Carolina, United States. The right-hand circularly polarized (RHCP) signals from this solar radio burst caused a corresponding decrease in the carrier-to-noise ratio of about 2.3 dB across all visible satellites. The maximum solar radio burst power associated with this event was 8700 solar flux units (1 SFU = 10-22 W/m2/Hz) RHCP at 1600 MHz. Direct observations of GPS semicodeless L2 carrier-to-noise ratio degradation from receivers in Brazil are also presented for a solar radio burst that occurred on 28 October 2003. The maximum degradation at GPS L1 was about 3.0 dB, and a degradation of 10.0 dB was observed on the semicodeless L2 signal. Scaling to historic solar radio burst records suggests that GPS L1 receivers could fail to produce a navigation solution and that semicodeless L1/L2 receivers will fail.
BibTeX:
@article{Cerruti2006,
  author = {Cerruti, Alessandro P. and Kintner, Paul M. and Gary, Dale E. and Lanzerotti, Louis J. and de Paula, Eurico R. and Vo, Hien B.},
  title = {Observed solar radio burst effects on GPS/Wide Area Augmentation System carrier-to-noise ratio},
  journal = {Space Weather},
  year = {2006},
  volume = {4},
  number = {10},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006SW000254},
  doi = {10.1029/2006SW000254}
}
Comarazamy DE, Gonzalez JE, Tepley CA, Raizada S and Pandya RVR (2006), "Effects of atmospheric particle concentration on cloud microphysics over Arecibo", Journal of Geophysical Research: Atmospheres. Vol. 111(D9), pp. n/a-n/a.
Abstract: A new cloud microphysics module incorporated to a regional atmospheric model and atmospheric particle (AP) observations performed at the Arecibo Observatory were used to simulate two short precipitation events observed in the area of the observatory and to investigate the possible effects of AP on cloud formation and rain development. First, model runs were performed with and without the new cloud module, initialized with the new AP data set and the previous cloud spectrum available. The combination of the new cloud module and the Arecibo observations produced the most satisfactory results and significant improvements in total precipitation modeled: 70 versus 80 mm observed. The improvement results in 15% more precipitation predicted when compared with the old cloud information and more than 50% with respect to simulations without cloud condensation nuclei activation. Then, a set of idealized runs showed that cloud droplet production is significantly larger in polluted air than in clear skies and that rainwater in polluted air is less than that in unpolluted air. This may be because existing droplets will compete more vigorously for the available water vapor and will not reach the necessary radius to fall, and therefore growth by collision and coalescence is subdued.
BibTeX:
@article{Comarazamy2006,
  author = {Comarazamy, Daniel E. and Gonzalez, Jorge E. and Tepley, Craig A. and Raizada, Shikha and Pandya, R. V. R.},
  title = {Effects of atmospheric particle concentration on cloud microphysics over Arecibo},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2006},
  volume = {111},
  number = {D9},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JD006243},
  doi = {10.1029/2005JD006243}
}
Delgado R, Weiner BR and Friedman JS (2006), "Chemical model for mid-summer lidar observations of mesospheric potassium over the Arecibo Observatory", Geophysical Research Letters. Vol. 33(2), pp. n/a-n/a.
Abstract: To understand the mid-summer nocturnal mesospheric K layer over the Arecibo Observatory (18.35°N, 66.75°W) a one dimensional model has been developed. Focusing on nights with no sporadic layer activity, we identify possible molecular reservoirs and sinks in the K layer using ab initio calculations to estimate the thermochemistry. Reactions KN2+ + O, KN2+ + CO2, and KHCO3 + H play primary roles in the chemistry of ionic and neutral potassium in the mesospheric cycle. The predominant potassium species is KHCO3 as a result of the influence of odd oxygen/hydrogen chemistry. The study of the metal layer contributes to a better understanding of chemical and dynamic changes that affect atmospheric composition.
BibTeX:
@article{Delgado2006,
  author = {Delgado, RubÈn and Weiner, Brad R. and Friedman, Jonathan S.},
  title = {Chemical model for mid-summer lidar observations of mesospheric potassium over the Arecibo Observatory},
  journal = {Geophysical Research Letters},
  year = {2006},
  volume = {33},
  number = {2},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005GL024326},
  doi = {10.1029/2005GL024326}
}
Emmert JT, Faivre ML, Hernandez G, Jarvis MJ, Meriwether JW, Niciejewski RJ, Sipler DP and Tepley CA (2006), "Climatologies of nighttime upper thermospheric winds measured by ground-based Fabry-Perot interferometers during geomagnetically quiet conditions: 1. Local time, latitudinal, seasonal, and solar cycle dependence", Journal of Geophysical Research: Space Physics. Vol. 111(A12), pp. n/a-n/a.
Abstract: We analyze ground-based Fabry-Perot interferometer observations of upper thermospheric (~250 km) horizontal neutral winds derived from Doppler shifts in the 630.0 nm (red line) nightglow. The winds were measured over the following locations: South Pole (90°S), Halley (76°S, 27°W), Arequipa (17°S, 72°W), Arecibo (18°N, 67°W), Millstone Hill (43°N, 72°W), Sondre StrÜmfjord (67°N, 51°W), and Thule (77°N, 68°W). We derive climatological quiet time (Kp < 3) wind patterns as a function of local time, solar cycle, day of year, and the interplanetary magnetic field (IMF), and provide parameterized representations of these patterns. At the high-latitude stations, and at Arequipa near the geomagnetic equator, wind speeds tend to increase with increasing solar extreme ultraviolet (EUV) irradiance. Over Millstone Hill and Arecibo, solar EUV has a negative effect on wind magnitudes. As represented by the 10.7 cm radio flux proxy, the solar EUV dependence of the winds at all latitudes is characterized by a saturation or weakening of the effect above moderate values (F10.7 > 150). The seasonal dependence of the winds is generally annual, but there are isolated cases in which a semiannual variation is observed. Within the austral winter, winds measured from the South Pole show a substantial intraseasonal variation only along longitudes directed toward the magnetic pole. IMF effects are described in a companion paper.
BibTeX:
@article{Emmert2006,
  author = {Emmert, J. T. and Faivre, M. L. and Hernandez, G. and Jarvis, M. J. and Meriwether, J. W. and Niciejewski, R. J. and Sipler, D. P. and Tepley, C. A.},
  title = {Climatologies of nighttime upper thermospheric winds measured by ground-based Fabry-Perot interferometers during geomagnetically quiet conditions: 1. Local time, latitudinal, seasonal, and solar cycle dependence},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A12},
  pages = {n/a-n/a},
  doi = {10.1029/2006JA011948}
}
Fritts DC, Janches D, Riggin DM, Stockwell RG, Sulzer MP and Gonzalez S (2006), "Gravity waves and momentum fluxes in the mesosphere and lower thermosphere using 430 MHz dual-beam measurements at Arecibo: 2. Frequency spectra, momentum fluxes, and variability", Journal of Geophysical Research: Atmospheres. Vol. 111(D18), pp. n/a-n/a.
Abstract: Janches et al. (2006) described a new dual-beam use of the 430 MHz incoherent scatter radar at the Arecibo Observatory in Puerto Rico. We found the technique to define the radial wind field in the mesosphere and lower thermosphere with sufficient accuracy to characterize gravity waves occurring at high frequencies and small spatial scales over an extended altitude range. The coplanar, dual-beam experiment was also designed to test the ability of the system to measure gravity wave momentum fluxes and their frequency distributions, and we report here on those results. Initial measurements were of limited duration and necessarily represent a case study, but they demonstrate the value of such measurements for studies of GW variability and large-scale interactions. Radial velocity variances reveal preferential eastward propagation for most intervals and altitudes, with the greatest propagation bias at lower altitudes and later times on 11 September when strong westward mean winds favor strong gravity filtering. The momentum fluxes observed during this experiment had ~50-min averages that were often near zero, occasionally achieved amplitudes of ~20 to 50 m2s-2, displayed significant consistency in altitude, and exhibited an approximate anticorrelation with the zonal wind field in cases with significant momentum fluxes. Frequency spectra defined the major contributions to the momentum fluxes, while S transforms were employed to examine the temporal variability of the GWs and momentum fluxes in greater detail.
BibTeX:
@article{Fritts2006,
  author = {Fritts, David C. and Janches, Diego and Riggin, Dennis M. and Stockwell, Robert G. and Sulzer, Michael P. and Gonzalez, Sixto},
  title = {Gravity waves and momentum fluxes in the mesosphere and lower thermosphere using 430 MHz dual-beam measurements at Arecibo: 2. Frequency spectra, momentum fluxes, and variability},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2006},
  volume = {111},
  number = {D18},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JD006883},
  doi = {10.1029/2005JD006883}
}
Janches D, Heinselman CJ, Chau JL, Chandran A and Woodman R (2006), "Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars", Journal of Geophysical Research: Space Physics. Vol. 111(A7), pp. n/a-n/a.
BibTeX:
@article{Janches2006,
  author = {Janches, Diego and Heinselman, Craig J. and Chau, Jorge L. and Chandran, Amal and Woodman, Ronald},
  title = {Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A7},
  pages = {n/a-n/a},
  doi = {10.1029/2006JA011628}
}
Janches D, Fritts DC, Riggin DM, Sulzer MP and Gonzalez S (2006), "Gravity waves and momentum fluxes in the mesosphere and lower thermosphere using 430 MHz dual-beam measurements at Arecibo: 1. Measurements, methods, and gravity waves", Journal of Geophysical Research: Atmospheres. Vol. 111(D18), pp. n/a-n/a.
Abstract: We report here and in a companion paper by Fritts et al. (2006a) on a new use of the UHF radar at the Arecibo Observatory in Puerto Rico. We have employed the 430 MHz radar for incoherent scatter measurements of radial wind spectra at altitudes from ~71 to 95 km using the Gregorian and line-feed antennas to define beam angles inclined 15° to the east and west of zenith. We find that the two beams define radial velocities with sufficient accuracy to characterize both the gravity waves and the momentum fluxes due to these waves over the majority of the observed altitude range during daylight hours. The characteristics of the gravity waves inferred from these measurements include (1) vertical scales ranging from ~2 to 20 km, (2) downward phase progression of the dominant gravity waves up to ~5 ms-1, and (3) vertical wave number spectra having slopes near a value (-3) expected for saturated gravity waves. Gravity wave frequency spectra and momentum fluxes are addressed in the companion paper.
BibTeX:
@article{Janches2006a,
  author = {Janches, Diego and Fritts, David C. and Riggin, Dennis M. and Sulzer, Michael P. and Gonzalez, Sixto},
  title = {Gravity waves and momentum fluxes in the mesosphere and lower thermosphere using 430 MHz dual-beam measurements at Arecibo: 1. Measurements, methods, and gravity waves},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2006},
  volume = {111},
  number = {D18},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JD006882},
  doi = {10.1029/2005JD006882}
}
Coles WA, Harmon JK, Sulzer MP, Chau JL and Woodman RF (2006), "An upper bound on the solar radar cross section at 50 MHz", Journal of Geophysical Research: Space Physics. Vol. 111(A4), pp. n/a-n/a.
Abstract: We have made 16 unsuccessful attempts, in February and October 2003, and February 2004, to observe solar echoes using the 50 MHz radar at Jicamarca in Peru. The upper bound that we have determined on the solar cross section is significantly lower than the average of earlier reported observations. In this paper we will describe the observations, discuss the noise and interference from solar bursts, and suggest possible reasons why the echo might be weaker than expected.
BibTeX:
@article{JGRA:JGRA18173,
  author = {Coles, W. A. and Harmon, J. K. and Sulzer, M. P. and Chau, J. L. and Woodman, R. F.},
  title = {An upper bound on the solar radar cross section at 50 MHz},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A4},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2005JA011416},
  doi = {10.1029/2005JA011416}
}
PintÈr B, Thom SD, Balthazor R, Vo H and Bailey GJ (2006), "Modeling subauroral polarization streams equatorward of the plasmapause footprints", Journal of Geophysical Research: Space Physics. Vol. 111(A10), pp. n/a-n/a.
Abstract: We report on a modeling study on the effects of subauroral polarization stream (SAPS) events equatorward of the plasmapause footprints, using the Sheffield Coupled Thermosphere-Ionosphere-Plasmasphere (CTIP) model. SAPS events are simulated by imposing a poleward electric field for 2 hours in the premidnight sector between 50° and 60° magnetic latitude. The presence of the SAPS results in a decrease in vertical total electron count and F region ion density, while the height of the F region can rise by up to 100 km. A study of the relative importance of the physical processes finds that the most significant contribution is the temperature increase due to ion-neutral friction, resulting in increased reaction rates of O+ loss. The recovery time for the SAPS studied is up to 10 hours.
BibTeX:
@article{JGRA:JGRA18208,
  author = {PintÈr, B. and Thom, S. D. and Balthazor, R. and Vo, H. and Bailey, G. J.},
  title = {Modeling subauroral polarization streams equatorward of the plasmapause footprints},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A10},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2005JA011457},
  doi = {10.1029/2005JA011457}
}
Luan X, Liu L, Wan W, Lei J, Zhang S-R, Holt JM and Sulzer MP (2006), "A study of the shape of topside electron density profile derived from incoherent scatter radar measurements over Arecibo and Millstone Hill", Radio Science. Vol. 41(4), pp. n/a-n/a.
Abstract: The shape of the topside electron density (Ne) profile is studied using incoherent scatter radar (ISR) measurements. On the basis of more than 90,000 and 84,000 Ne profiles measured over Arecibo (18.4°N, 66.7°W, dip 49.7°) and Millstone Hill (42.6°N, 71.5°W, dip 71.6°), respectively, shape factors have been derived by fitting the ISR observed profile using a Chapman-type layer with a height-independent scale height. The results reveal that the shape factor shows a general departure from the typically used values of 0.5 (Chapman ? layer) except during the night and also undergoes appreciable variation with local time, season, solar activity, and latitude. Over Arecibo, the averaged shape factor is characterized by a daytime maximum of ?0.55–0.75, a nearly constant nighttime value close to 0.5, and a marked morning decline; over Millstone Hill, the shape factor shows pronounced seasonal variations, and the diurnal variation in summer is opposite to that in other seasons. Over both stations, the shape factor exhibits a high correlation with the F2 layer peak electron density (NmF2), and it has strong solar cycle dependence during the late morning hours. It indicates that the temperature structure of the topside ionosphere can explain much of the variation of the shape factor when the plasma density is low, especially during nighttime. During daytime hours, the topside shape factor is thought to be associated with ion-neutral drag during periods of large plasma density.
BibTeX:
@article{Luan2006,
  author = {Luan, Xiaoli and Liu, Libo and Wan, Weixing and Lei, Jiuhou and Zhang, Shun-Rong and Holt, John M. and Sulzer, Michael P.},
  title = {A study of the shape of topside electron density profile derived from incoherent scatter radar measurements over Arecibo and Millstone Hill},
  journal = {Radio Science},
  year = {2006},
  volume = {41},
  number = {4},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005RS003367},
  doi = {10.1029/2005RS003367}
}
Martinis C, Baumgardner J, Smith SM, Colerico M and Mendillo M (2006), "Imaging science at El Leoncito, Argentina", Annales Geophysicae. Vol. 24(5), pp. 1375-1385.
BibTeX:
@article{Martinis2006,
  author = {Martinis, C. and Baumgardner, J. and Smith, S. M. and Colerico, M. and Mendillo, M.},
  title = {Imaging science at El Leoncito, Argentina},
  journal = {Annales Geophysicae},
  year = {2006},
  volume = {24},
  number = {5},
  pages = {1375-1385},
  doi = {10.5194/angeo-24-1375-2006}
}
Mika A, Haldoupis C, Neubert T, Su HT, Hsu RR, Steiner RJ and Marshall RA (2006), "Early VLF perturbations observed in association with elves", Annales Geophysicae. Vol. 24(8), pp. 2179-2189.
BibTeX:
@article{Mika2006,
  author = {Mika, A. and Haldoupis, C. and Neubert, T. and Su, H. T. and Hsu, R. R. and Steiner, R. J. and Marshall, R. A.},
  title = {Early VLF perturbations observed in association with elves},
  journal = {Annales Geophysicae},
  year = {2006},
  volume = {24},
  number = {8},
  pages = {2179-2189},
  doi = {10.5194/angeo-24-2179-2006}
}
Nicolls MJ, Sulzer MP, Aponte N, Seal R, Nikoukar R and Gonzalez SA (2006), "High-resolution electron temperature measurements using the plasma line asymmetry", Geophysical Research Letters. Vol. 33(18), pp. n/a-n/a.
Abstract: In this paper, we present the first results of a new technique for measuring the electron temperature in the daytime ionosphere using the Arecibo incoherent scatter radar (ISR). The technique utilizes the plasma line component of the incoherent scatter spectrum. The difference in the up- and down-shifted plasma line frequencies is related to the density and temperature of the ionosphere, as well as more minor effects resulting from photoelectrons, currents, and other sources. The shift is very small (the order of 1 kHz in a plasma line frequency of several MHz) but can be measured quite accurately with the coded long pulse plasma line technique. We compare the results to ion line measurements of the electron temperature, and the two independent techniques show good agreement. In addition to providing a measure of the electron temperature that is independent of the ion line, the approach allows for a sensitive test of kinetic plasma theory including a magnetic field, gives us the ability to study photoelectron populations and electron currents, and will allow us to constrain ion line fits in the bottomside (and possibly topside) regions to more accurately fit for composition.
BibTeX:
@article{Nicolls2006,
  author = {Nicolls, M. J. and Sulzer, M. P. and Aponte, N. and Seal, R. and Nikoukar, R. and Gonzalez, S. A.},
  title = {High-resolution electron temperature measurements using the plasma line asymmetry},
  journal = {Geophysical Research Letters},
  year = {2006},
  volume = {33},
  number = {18},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2006GL027222},
  doi = {10.1029/2006GL027222}
}
Nicolls MJ, Aponte N, Gonzalez SA, Sulzer MP and Oliver WL (2006), "Daytime F region ion energy balance at Arecibo for moderate to high solar flux conditions", Journal of Geophysical Research: Space Physics. Vol. 111(A10), pp. A10307 (16 pages).
Abstract: Ion energy balance studies using incoherent scatter radar (ISR) data involve the estimation of the neutral density and exospheric temperature from the ISR-measured parameters using theoretical collision cross sections. The ratio [O]radar/[O]MSIS in long-term averages is an estimate of the so-called Burnside factor and can be derived from these studies. This parameter is thought to be associated with errors in the O+-O collision cross section. The most recent comparison between the Mass Spectrometer Incoherent Scatter (MSIS) neutral atomic oxygen densities and values derived from Arecibo ISR measurements using ion energy balance shows large discrepancies for high solar flux conditions. In contrast to ion momentum studies, which typically lead to a Burnside factor greater than 1 (usually near 1.2–1.3), the discrepancies between MSIS densities and radar-derived values tend to result in low values (near 0.8) for the Burnside factor. Various interpretations of this discrepancy have been put forward. We have reanalyzed the Arecibo ISR World Day data from 1988 to 1994, corresponding to the moderate to high solar flux period of solar cycle 22. By extending the analysis to the upper F region/lower topside (and explicitly including the role of H+, which is often neglected) we obtain consistent results for the neutral density and exospheric temperature that show no significant long-term discrepancy from the MSIS predictions. For this period, we obtain a median ratio [O]radar/[O]MSIS of 1.26 ± 0.02 using the O+-O collision cross section from Banks (1966). The standard deviation of the data is about 0.35. This ratio is close to the most recently published theoretical simulations of the collision cross section within the uncertainties. Knowing the correct O+-O collision cross section allows one to extract the neutral parameters from the radar data and study short-term (day-to-day) variations in those parameters.
BibTeX:
@article{Nicolls2006a,
  author = {Nicolls, Michael J. and Aponte, NÈstor and Gonzalez, Sixto A. and Sulzer, Michael P. and Oliver, William L.},
  title = {Daytime F region ion energy balance at Arecibo for moderate to high solar flux conditions},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A10},
  pages = {A10307 (16 pages)},
  url = {http://dx.doi.org/10.1029/2006JA011664},
  doi = {10.1029/2006JA011664}
}
Pavlov AV, Fukao S and Kawamura S (2006), "A modeling study of ionospheric F2-region storm effects at low geomagnetic latitudes during 17-22 March 1990", Annales Geophysicae. Vol. 24(3), pp. 915-940.
BibTeX:
@article{Pavlov2006,
  author = {Pavlov, A. V. and Fukao, S. and Kawamura, S.},
  title = {A modeling study of ionospheric F2-region storm effects at low geomagnetic latitudes during 17-22 March 1990},
  journal = {Annales Geophysicae},
  year = {2006},
  volume = {24},
  number = {3},
  pages = {915-940},
  doi = {10.5194/angeo-24-915-2006}
}
Pavlov AV (2006), "The role of the zonal E&times;B plasma drift in the low-latitude ionosphere at high solar activity near equinox from a new three-dimensional theoretical model", Annales Geophysicae. Vol. 24(10), pp. 2553-2572.
BibTeX:
@article{Pavlov2006a,
  author = {Pavlov, A. V.},
  title = {The role of the zonal E&times;B plasma drift in the low-latitude ionosphere at high solar activity near equinox from a new three-dimensional theoretical model},
  journal = {Annales Geophysicae},
  year = {2006},
  volume = {24},
  number = {10},
  pages = {2553-2572},
  doi = {10.5194/angeo-24-2553-2006}
}
Waldrop LS, Kudeki E, Gonzalez SA, Sulzer MP, Garcia R, Butala M and Kamalabadi F (2006), "Derivation of neutral oxygen density under charge exchange in the midlatitude topside ionosphere", Journal of Geophysical Research: Space Physics. Vol. 111(A11), pp. n/a-n/a.
BibTeX:
@article{Waldrop2006,
  author = {Waldrop, L. S. and Kudeki, E. and Gonzalez, S. A. and Sulzer, M. P. and Garcia, R. and Butala, M. and Kamalabadi, F.},
  title = {Derivation of neutral oxygen density under charge exchange in the midlatitude topside ionosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2006},
  volume = {111},
  number = {A11},
  pages = {n/a-n/a},
  doi = {10.1029/2005JA011496}
}
Zhou Q and Morton YT (2006), "A case study of mesospheric gravity wave momentum flux and dynamical instability using the Arecibo dual beam incoherent scatter radar", Geophysical Research Letters. Vol. 33(10), pp. L10802 (4 pages).
Abstract: We report the first observation of gravity wave momentum flux in the mesosphere using the dual-beam Arecibo incoherent scatter radar (ISR). Quasi-monochromatic waves were observed throughout the daytime of July 28, 2001 in the altitude range of 65–85 km. The largest wave speed was about 100 m/s and the dominant period was about 15 min. Instability, as indicated by the Richardson number, occurred at several altitudes, most dramatically at 77 and 81 kilometers. The zonal momentum flux is found to change sign at altitudes where dynamical instability occurs. No significant gravity waves were observed in the region having an eastward background wind, while they were ubiquitous when the background wind was westward.
BibTeX:
@article{Zhou2006,
  author = {Zhou, Qihou and Morton, Y. T.},
  title = {A case study of mesospheric gravity wave momentum flux and dynamical instability using the Arecibo dual beam incoherent scatter radar},
  journal = {Geophysical Research Letters},
  year = {2006},
  volume = {33},
  number = {10},
  pages = {L10802 (4 pages)},
  url = {http://dx.doi.org/10.1029/2005GL025608},
  doi = {10.1029/2005GL025608}
}
Abdu M, Batista I, Carrasco A and Brum C (2005), "South Atlantic magnetic anomaly ionization: A review and a new focus on electrodynamic effects in the equatorial ionosphere ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 67(17-18), pp. 1643 - 1657.
Abstract: Satellite observations of enhanced energetic particle fluxes in the South Atlantic Magnetic Anomaly (SAMA) region have been supported by ground-based observations of enhanced ionization induced by particle precipitation in the ionosphere over this region. Past observations using a variety of instruments such as vertical sounding ionosondes, riometers and VLF receivers have provided evidences of the enhanced ionization due to energetic particle precipitation in the ionosphere over Brazil. The extra ionization at E-layer heights could produce enhanced ionospheric conductivity within and around the SAMA region. The energetic particle ionization source that is operative even under “quiet” conditions can undergo significant enhancements during magnetospheric storm disturbances, when the geographic region of enhanced ionospheric conductivity can extend to magnetic latitudes closer to the equator where the magnetic field line coupling of the E and F regions plays a key role in the electrodynamics of the equatorial ionosphere. Of particular interest are the sunset electrodynamic processes responsible for equatorial spread F/plasma bubble irregularity generation and related dynamics (zonal and vertical drifts, etc.). The SAMA represents a source of significant longitudinal variability in the global description of the equatorial spread F irregularity phenomenon. Recent results from digital ionosondes operated at Fortaleza and Cachoeira Paulista have provided evidence that enhanced ionization due to particle precipitation associated with magnetic disturbances, in the SAMA region, can indeed significantly influence the equatorial electrodynamic processes leading to plasma irregularity generation and dynamics. Disturbance magnetospheric electric fields that penetrate the equatorial latitudes during storm events seem to be intensified in the SAMA region based on ground-based and satellite-borne measurements. This paper will review our current understanding of the influence of SAMA on the equatorial electrodynamic processes from the perspective outlined above.
BibTeX:
@article{Abdu2005,
  author = {M.A. Abdu and I.S. Batista and A.J. Carrasco and C.G.M. Brum},
  title = {South Atlantic magnetic anomaly ionization: A review and a new focus on electrodynamic effects in the equatorial ionosphere },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2005},
  volume = {67},
  number = {17-18},
  pages = {1643 - 1657},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682605001240},
  doi = {10.1016/j.jastp.2005.01.014}
}
Aponte N, Nicolls MJ, Gonzales SA, Sulzer MP, Kelley MC, Robles E and Tepley CA (2005), "Instantaneous electric field measurements and derived neutral winds at Arecibo", Geophysical Research Letters. Vol. 32(12), pp. n/a-n/a.
Abstract: Previously, ion vector velocity measurements at Arecibo required the rotation of the antenna (a 360° rotation takes about 15 minutes) in order to accumulate enough information from different directions. In addition, a least-squares fitting method or a more sophisticated inversion technique is necessary to determine horizontal velocities. This study reports the first instantaneous long-duration F region vector velocity measurements in the magnetic meridian plane using the dual-beam system. This configuration is suitable for measuring the eastward electric field and deriving the meridional neutral wind with very high time resolution. The first results of this experiment presented here seem to show evidence for a gravity wave driven plasma process.
BibTeX:
@article{Aponte2005,
  author = {Aponte, Nestor and Nicolls, Michael J. and Gonzales, Sixto A. and Sulzer, M. P. and Kelley, Michael C. and Robles, Eva and Tepley, Craig A.},
  title = {Instantaneous electric field measurements and derived neutral winds at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2005},
  volume = {32},
  number = {12},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005GL022609},
  doi = {10.1029/2005GL022609}
}
Bhat NDR, Cordes JM, Chatterjee S and Lazio TJW (2005), "Radio frequency interference identification and mitigation using simultaneous dual-station observations", Radio Science. Vol. 40(5), pp. n/a-n/a.
Abstract: Radio frequency interference (RFI) mitigation is a critically important issue in radio astronomy using existing instruments as well as in the development of next generation radio telescopes, such as the Square Kilometer Array (SKA). Most designs for the SKA involve multiple stations with spacings of up to a few thousands of kilometers and thus can exploit the drastically different RFI environments at different stations. As demonstrator observations and analysis for SKA-like instruments, and to develop RFI mitigation schemes that will be useful in the near term, we recently conducted simultaneous observations with Arecibo Observatory and the Green Bank Telescope. The observations were aimed at diagnosing RFI and using the mostly uncorrelated RFI between the two sites to excise RFI from several generic kinds of measurements such as giant pulses from Crab-like pulsars and weak H I emission from galaxies in bands heavily contaminated by RFI. This paper presents observations, analysis, and RFI identification and excision procedures that are effective for both time series and spectroscopy applications using multistation data.
BibTeX:
@article{Bhat2005,
  author = {Bhat, N. D. R. and Cordes, J. M. and Chatterjee, S. and Lazio, T. J. W.},
  title = {Radio frequency interference identification and mitigation using simultaneous dual-station observations},
  journal = {Radio Science},
  year = {2005},
  volume = {40},
  number = {5},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2004RS003172},
  doi = {10.1029/2004RS003172}
}
Contreira D, Rodrigues F, Makita K, Brum C, Gonzalez W, Trivedi N, da Silva M and Schuch N (2005), "An experiment to study solar flare effects on radio-communication signals ", Advances in Space Research . Vol. 36(12), pp. 2455-2459.
Abstract: The occurrence of radio signal fading events caused by ionospheric absorption plays an important role in the performance of radio-communication systems. It is necessary to know the magnitude and time-scale of such events in order to specify technical parameters of the communication system to be used. Generally, fading events are associated with solar flares, which are characterized by sudden increase in the solar X-ray flux that causes an increase in the ionization in the lower ionosphere. The abrupt increase of ionization causes the absorption of radio waves propagating in the Earth–ionosphere wave-guide and is reported as radio signal fading events. A simple experiment to monitor the behavior of lower ionosphere has been carried out at the Southern Space Observatory-SSO/INPE (29.43S, 53.8W), located in southern Brazil. The experiment is basically a computer controlled radio receiver that records the received signal strength of Amplitude Modulated (AM) radio signals in the HF (High Frequencies) range. We analyzed data of the 6MHz beacon signal that has been transmitted by a broadcasting radio station located about 400;km from the observation site. In this work we present initial results of daily variation of the received signal strength and fading events associated with solar flares observed in the 6MHz signal monitored by the experiment during 2001. X-ray solar flux data from the GOES-8 satellite were used to identify X-ray solar bursts associated with solar flares. Based on the one-year data collected by the experiment, a statistical summary of fading occurrences and their correlation with solar flares, as well as the distributions of time-scales and magnitudes of such events are presented.
BibTeX:
@article{Contreira2005,
  author = {D.B. Contreira and F.S. Rodrigues and K. Makita and C.G.M. Brum and W. Gonzalez and N.B. Trivedi and M.R. da Silva and N.J. Schuch},
  title = {An experiment to study solar flare effects on radio-communication signals },
  journal = {Advances in Space Research },
  year = {2005},
  volume = {36},
  number = {12},
  pages = {2455-2459},
  note = {Arecibo author},
  url = {http://www.sciencedirect.com/science/article/pii/S027311770500013X},
  doi = {10.1016/j.asr.2004.03.019}
}
Goncharenko LP, Salah JE, van Eyken A, Howells V, Thayer JP, Taran VI, Shpynev B, Zhou Q and Chau J (2005), "Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars", Annales Geophysicae. Vol. 23(1), pp. 163-181.
Abstract: This paper describes the ionospheric response to a geomagnetic storm beginning on 17 April 2002. We present the measurements of ionospheric parameters in the F-region obtained by the network of eight incoherent scatter radars. The main effects of this storm include a deep decrease in the electron density observed at high and middle latitudes in the pre-noon sector, and a minor enhancement in the density observed in the daytime sector at middle latitudes. Extreme plasma heating (>1000-3000 K) is observed at high latitudes, subsiding to 200-300K at subauroral latitudes. The western hemisphere radar chain observed the prompt penetration of the electric field from auroral to equatorial latitudes, as well as the daytime enhancement of plasma drift parallel to the magnetic field line, which is related to the enhancement in the equatorward winds. We suggest that in the first several hours after the storm onset, a negative phase above Millstone Hill (pre-noon sector) results from counteracting processes - penetration electric field, meridional wind, and electrodynamic heating, with electrodynamic heating being the dominant mechanism. At the lower latitude in the pre-noon sector (Arecibo and Jicamarca), the penetration electric field becomes more important, leading to a negative storm phase over Arecibo. In contrast, in the afternoon sector at mid-latitudes (Kharkov, Irkutsk), effects of penetration electric field and meridional wind do not counteract, but add up, leading to a small (~15%), positive storm phase over these locations. As the storm develops, Millstone Hill and Irkutsk mid-latitude radars observe further depletion of electron density due to the changes in the neutral composition.
BibTeX:
@article{Goncharenko2005,
  author = {Goncharenko, L. P. and Salah, J. E. and van Eyken, A. and Howells, V. and Thayer, J. P. and Taran, V. I. and Shpynev, B. and Zhou, Q. and Chau, J.},
  title = {Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars},
  journal = {Annales Geophysicae},
  year = {2005},
  volume = {23},
  number = {1},
  pages = {163-181},
  doi = {10.5194/angeo-23-163-2005}
}
Gonzalez SA, Nicolls MJ, Sulzer MP and Aponte N (2005), "An energy balance study of the lower topside ionosphere using the Arecibo incoherent scatter radar and heating facilities", Journal of Geophysical Research: Space Physics. Vol. 110(A11), pp. n/a-n/a.
Abstract: In this paper we describe the results of an experiment to study electron and ion temperature enhancements during an HF modification experiment at the Arecibo Observatory. This experiment is unique in that we pointed the radar away from the interaction region in the F region in order to study heat conduction along the field lines. Although electron temperature enhancements have been frequently observed when high-power radio waves are injected into the ionosphere, observations generally have occurred in the interaction region and the regions of elevated electron temperatures have been accompanied by small ion temperature increases (50–200 K). Like many such experiments, this one was conducted during winter solar minimum, when f0F2 is low during the night at midlatitudes, but this experiment also had the advantage of the upgraded Arecibo HF facility, first used in 1997. The electron temperature enhancements were accompanied by a significant increase in the ion temperature (nearly 500 K). The observation away from the interaction region allowed the application of the time-dependent heating equation without having to estimate local heating effects (i.e., by keeping the conduction and loss terms in the energy balance calculation and neglecting the source term). More specifically, the heating rate of conduction was quantified by manipulating the heat equation. Thus the primary purpose was to observe the temperatures as the heat was conducted away from the F region ionosphere. We have observed the gradients in the electron temperature caused by the heater, estimated the conduction along the field lines, and studied the transfer of energy from the hot electrons to the ions and neutrals. At lower altitudes, near the electron-temperature peak, we show that O+ cooling is dominant, whereas in the lower topside H+ cooling is the most important. Experiments of the type described here could be enhanced with the new dual-beam system at Arecibo in conjunction with a heating facility.
BibTeX:
@article{Gonzalezs2005,
  author = {Gonzalez, S A. and Nicolls, Michael J. and Sulzer, Michael P. and Aponte, Nestor},
  title = {An energy balance study of the lower topside ionosphere using the Arecibo incoherent scatter radar and heating facilities},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A11},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JA011154},
  doi = {10.1029/2005JA011154}
}
Janches D and ReVelle DO (2005), "Initial altitude of the micrometeor phenomenon: Comparison between Arecibo radar observations and theory", Journal of Geophysical Research: Space Physics. Vol. 110(A8), pp. n/a-n/a.
Abstract: We present calculations of the altitude at which the micrometeor phenomenon begins, that is, the point where the interaction between micrometeoroids and the Earth's atmosphere becomes important. At these altitudes, physical processes such as light emission, heating, electron production, etc., begin to occur. The calculations are performed using four very different initial height models including (1) solving the full integration of the single-body meteor equations, (2) using a balance between the loss of momentum and the component of the acceleration due to gravity along the meteor trajectory, (3) using a solution that emanates from a “linearized” form of the meteor energy equation but without including either atmosphere or meteoroid radiation emission effects, and finally (4) utilizing a solution of the meteor energy equation that is specifically approximated for small particles. We compare our evaluated theoretical results with direct micrometeor observations detected using the 430 MHz Arecibo Observatory (AO) radar system. The goal of these calculations is to provide reliable initial conditions in order to completely model the AO micrometeor observations, most of which have nearly constant decelerations. The nature of this study, although performed with already existing theoretical formulations, is of unprecedented value because it is the first study where these models are directly compared against very highly resolved micrometeor velocity and altitude distributions that are derived directly from the radar observations. We found that the meteor energy equation approximated for small particles agrees very well with the radar observations, in particular for meteor melting temperatures of the order of 2100 K and entry angles lower than 30° with respect to the radar beam normal direction. Unfortunately, from this model the composition characteristics of the particles detected by the AO radar cannot conclusively be drawn. However, comparison with the calculation of the penetration height of meteoroids reported by ReVelle (2005a) suggests that chondritic material seem to be the best candidate to explain the observed penetration of these particles in the mesosphere. Calculation of the light emission and electron density production of the meteor are also presented and discussed.
BibTeX:
@article{Janches2005,
  author = {Janches, Diego and ReVelle, Douglas O.},
  title = {Initial altitude of the micrometeor phenomenon: Comparison between Arecibo radar observations and theory},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A8},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JA011022},
  doi = {10.1029/2005JA011022}
}
Janches D and Chau J (2005), "Observed diurnal and seasonal behavior of the micrometeor flux using the Arecibo and Jicamarca radars ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 67(13), pp. 1196-1210.
BibTeX:
@article{Janches2005a,
  author = {D. Janches and J.L. Chau},
  title = {Observed diurnal and seasonal behavior of the micrometeor flux using the Arecibo and Jicamarca radars },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2005},
  volume = {67},
  number = {13},
  pages = {1196-1210},
  doi = {10.1016/j.jastp.2005.06.011}
}
Harmon JK and Coles WA (2005), "Modeling radio scattering and scintillation observations of the inner solar wind using oblique AlfvÈn/ion cyclotron waves", Journal of Geophysical Research: Space Physics. Vol. 110(A3), pp. n/a-n/a.
Abstract: Radio scattering and scintillation observations of the near-Sun solar wind are shown to be dominated by effects associated with obliquely propagating AlfvÈn/ion cyclotron waves. We base this on a modeling of structure functions from angular/spectral broadening observations and velocity measurements from interplanetary scintillation (IPS) observations. A simple damped-WKB model was found inadequate, as Landau damping erodes the spectrum faster than is consistent with the observed inner scale. Invoking a turbulent cascade can counteract this damping and push the spectral cutoff back out to the observed inner scale near the ion inertial scale. Adjusting the spectrum amplitude and cascade rate to match observations gives an estimate of the wave dissipation power associated with electron Landau damping and proton cyclotron damping. The implied power levels are substantial, being comparable with levels typically invoked in extended wave heating models. Both the shape and the amplitude of the observed structure functions can be explained by a composite spectrum made up of a power law component of passive or non-AlfvÈnic density fluctuations and a local flattening associated with the enhanced linear AlfvÈn wave compressibility at small (ion cyclotron) scales. Since IPS is dominated by the enhanced small-scale density fluctuations, the scintillation velocity field should show a strong wave effect. Our modeling of IPS velocities does, in fact, show that the large parallel velocity spread and upward bias to the mean velocity observed near the Sun are a direct result of the density fluctuations associated with AlfvÈn waves along an extended line of sight.
BibTeX:
@article{JGRA:JGRA17735,
  author = {Harmon, John K. and Coles, William A.},
  title = {Modeling radio scattering and scintillation observations of the inner solar wind using oblique AlfvÈn/ion cyclotron waves},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A3},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2004JA010834},
  doi = {10.1029/2004JA010834}
}
Kuo SP and Lee MC (2005), "Cascade spectrum of HF enhanced plasma lines generated in HF heating experiments", Journal of Geophysical Research: Space Physics. Vol. 110(A1), pp. n/a-n/a.
BibTeX:
@article{Kuo2005,
  author = {Kuo, S. P. and Lee, M. C.},
  title = {Cascade spectrum of HF enhanced plasma lines generated in HF heating experiments},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A1},
  pages = {n/a-n/a},
  doi = {10.1029/2004JA010674}
}
Martin JD, Morton YT and Zhou Q (2005), "Neural network development for the forecasting of upper atmosphere parameter distributions ", Advances in Space Research . Vol. 36(12), pp. 2480-2485.
BibTeX:
@article{Martin2005,
  author = {Jeffrey D. Martin and Yu T. Morton and Qihou Zhou},
  title = {Neural network development for the forecasting of upper atmosphere parameter distributions },
  journal = {Advances in Space Research },
  year = {2005},
  volume = {36},
  number = {12},
  pages = {2480-2485},
  doi = {10.1016/j.asr.2003.12.015}
}
Nicolls MJ and Kelley MC (2005), "Strong evidence for gravity wave seeding of an ionospheric plasma instability", Geophysical Research Letters. Vol. 32(5), pp. n/a-n/a.
Abstract: Here we present evidence for gravity wave seeding of ionospheric plasma instabilities. On October 2, 2002 a series of magnetic substorms led to a large-scale traveling ionospheric disturbance (LSTID) that was detected by the Arecibo incoherent scatter radar. Several large oscillations of the F layer occurred, including one that lifted the layer to over 450 km. At least two shorter period oscillations were identified in the plasma contours along the bottomside of the layer. The largest amplitude signal exhibited a downward phase velocity, vertical wavelength, and period (~50 minutes) consistent with the linear theory of gravity waves. A ~30-minute period oscillation was amplified considerably when the bottomside was lifted to high altitudes near dawn. This amplification was likely due to a gravitational instability with a growth time of about 15 minutes. We believe that the LSTID created conditions conducive to instability, while the shorter period waves created the seed irregularities.
BibTeX:
@article{Nicolls2005,
  author = {Nicolls, Michael J. and Kelley, Michael C.},
  title = {Strong evidence for gravity wave seeding of an ionospheric plasma instability},
  journal = {Geophysical Research Letters},
  year = {2005},
  volume = {32},
  number = {5},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2004GL020737},
  doi = {10.1029/2004GL020737}
}
Pellinen-Wannberg A (2005), "Meteor head echoes - observations and models", Annales Geophysicae. Vol. 23, pp. 201-205.
BibTeX:
@article{Pellinen-Wannberg2005,
  author = {Pellinen-Wannberg, A},
  title = {Meteor head echoes - observations and models},
  journal = {Annales Geophysicae},
  year = {2005},
  volume = {23},
  pages = {201-205},
  doi = {10.5194/angeo-23-201-2005}
}
Petitdidier M and Laroche P (2005), "Lightning observations with the Strato-Tropospheric UHF and VHF radars at Arecibo, Puerto Rico", Atmospheric Research. Vol. 76(1-4), pp. 481-492.
Abstract: Observations were carried out at National Astronomy and Ionospheric Center (NAIC) in Puerto Rico with a dual-frequency (46.8MHz/430MHz) Strato-Tropospheric radar associated with ground-based precipitation and electrostatic field measurements. This experimental set-up is devoted to provide wind measurements and detection of clear air turbulence. During a thunderstorm event, VHF-UHF radar receivers detected wide frequency band radiation emitted by lightning flashes. We present in this paper observations of a specific storm for which lightning radiation and ionized lightning channel were fortuitously and simultaneously detected. A bi-level structure of the lightning flash channel is observed and is consistent with observations obtained previously by other authors with VHF lightning mapper.
BibTeX:
@article{Petitdidier2005,
  author = {Petitdidier, M and Laroche, P},
  title = {Lightning observations with the Strato-Tropospheric UHF and VHF radars at Arecibo, Puerto Rico},
  journal = {Atmospheric Research},
  year = {2005},
  volume = {76},
  number = {1-4},
  pages = {481-492},
  url = {http://www.sciencedirect.com/science/article/pii/S0169809505000724},
  doi = {10.1016/j.atmosres.2004.11.037}
}
Deshpande AA (2005), "Correlations of spectral intensity fluctuations: Application to radio frequency interference mitigation", Radio Science. Vol. 40(5), pp. n/a-n/a.
Abstract: This paper describes a technique based on correlating fluctuations in spectral intensities. When applied to intensity data recorded as a function of time and frequency, the result can be viewed in the form of a correlation map, wherein the temporal correlation between fluctuations in every possible pair of spectral channels is represented. In addition to serving as a useful diagnostic tool for the measuring system itself, such a correlation map offers a wealth of information on spectral channels affected by radio frequency interference (RFI) and intermodulation products, if any. Although such estimations are inherently less sensitive than those using voltage correlations, the technique promises much broader applicability since intensity data are more commonly available. The strengths and weaknesses of this technique with respect to RFI mitigation are discussed and are illustrated with real examples. An extension of this analysis to polarization data is also explored. A promising way to isolate RFI on the basis of its highly polarized nature is proposed, and relevant practical issues are discussed. The present study suggests that high-resolution time-frequency data for the full Stokes parameters allow effective excision of RFI (by typically more than 20 dB), particularly for observations of unpolarized astronomical sources. This method is exceedingly effective in situations where a large fraction of the data is affected by polarized RFI, where a robust statistics approach fails.
BibTeX:
@article{RDS:RDS5154,
  author = {Deshpande, Avinash A.},
  title = {Correlations of spectral intensity fluctuations: Application to radio frequency interference mitigation},
  journal = {Radio Science},
  year = {2005},
  volume = {40},
  number = {5},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2004RS003156},
  doi = {10.1029/2004RS003156}
}
ReVelle D (2005), "The Mesopause as a physical penetration boundary", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 67(13), pp. 1159-1170.
BibTeX:
@article{ReVelle2005,
  author = {D.O. ReVelle},
  title = {The Mesopause as a physical penetration boundary},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2005},
  volume = {67},
  number = {13},
  pages = {1159-1170},
  doi = {10.1016/j.jastp.2005.06.002}
}
Roper RG and Brosnahan JW (2005), "Diurnal variations in the rate of dissipation of turbulent energy in the equatorial uppermesosphereÁ€“lower thermosphere", Radio Science. Vol. 40(4), pp. n/a-n/a.
BibTeX:
@article{Roper2005,
  author = {Roper, R. G. and Brosnahan, J. W.},
  title = {Diurnal variations in the rate of dissipation of turbulent energy in the equatorial uppermesosphereÁ€“lower thermosphere},
  journal = {Radio Science},
  year = {2005},
  volume = {40},
  number = {4},
  pages = {n/a-n/a},
  doi = {10.1029/2004RS003198}
}
Smith SM, Friedman JS, Raizada S, Tepley CA, Baumgardner J and Mendillo M (2005), "Evidence of mesospheric bore formation from a breaking gravity wave event: simultaneous imaging and lidar measurements", Journal of Atmospheric and Terrestrial Physics. Vol. 67, pp. 345-356.
BibTeX:
@article{Smith2005,
  author = {Smith, S M and Friedman, J S and Raizada, S. and Tepley, C A and Baumgardner, J and Mendillo, M},
  title = {Evidence of mesospheric bore formation from a breaking gravity wave event: simultaneous imaging and lidar measurements},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {2005},
  volume = {67},
  pages = {345-356},
  note = {doi:10.1016/j.jastp.2004.11.008},
  doi = {10.1016/j.jastp.2004.11.008}
}
Sulzer MP, Aponte N and Gonzalez SA (2005), "Application of linear regularization methods to Arecibo vector velocities", Journal of Geophysical Research: Space Physics. Vol. 110(A10), pp. n/a-n/a.
Abstract: Estimates of the three-dimensional ion velocity field can be difficult to make with monostatic radars because there are three unknown components for each independent line of sight velocity measurement. To cope with this problem, one or more assumptions about the vector field must be made to arrive at a solution. At Arecibo, one can measure the ion vector velocities by continuously rotating the antenna beam back and forth 360 degrees in azimuth at 15 degrees off zenith to sample the horizontal components. Until recently, the line of sight velocities obtained from this experiment were typically converted into vector velocities by assuming that the vector field remains constant during one rotation and that horizontal gradients are negligible. In this paper we show how to apply the linear regularization inversion method to the problem of computing ion vector velocities. This technique improves the accuracy of the vector velocities obtained from the measured F region line of sight velocities and also provides a convenient way to do the computations for dual-beam experiments. The technique could improve the vector velocities at other monostatic incoherent scatter radar facilities.
BibTeX:
@article{Sulzer2005,
  author = {Sulzer, Michael P. and Aponte, NÈstor and Gonzalez, Sixto A.},
  title = {Application of linear regularization methods to Arecibo vector velocities},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A10},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JA011042},
  doi = {10.1029/2005JA011042}
}
Vlasov MN, Nicolls MJ, Kelley MC, Smith SM, Aponte N and Gonzalez SA (2005), "Modeling of airglow and ionospheric parameters at Arecibo during quiet and disturbed periods in October 2002", Journal of Geophysical Research: Space Physics. Vol. 110(A7), pp. n/a-n/a.
Abstract: The main purpose of this paper is to analyze observations of the 630.0-nm (red line) and 557.7-nm (green line) zenith airglow intensities measured during the month of October 2002 over Arecibo, Puerto Rico. We begin by describing an improved model for calculating the intensity of the red and green airglow lines that takes into account the role of molecular ions. We show, however, that at least for the data used in this study, it is not necessary to include the effects of molecular ions in our calculations. From observations of the airglow emissions on quiet days, we infer the general characteristics of the red-line intensities, which show a minimum before midnight and a peak after midnight. These results are consistent with a decrease in NmF2 and an increase in hmF2 before midnight, followed by the so-called “midnight collapse.” We then focus on the storm day of October 1-2, 2002, during which large-amplitude variations in both the red- and green-line intensities were observed and reproduced by the airglow model. An additional peak of NmF2, together with an hmF2 decrease, was observed before midnight, associated with the passage of a large-scale atmospheric gravity wave. The NmF2 nighttime increase requires plasma flux from the plasmasphere, which we find can be as large as 109 cm-2 s-1. The plasmasphere needs an additional source of plasma in order to provide such a large flux, and we explain this by considering the role of the meridional wind in the plasma exchange process. Strong changes in the shape of the F2 region were observed during the downward and upward motion of the F2 layer during the storm period. We have found simple analytical solutions for the height distributions of the electron density in the F2 region by including the effects of recombination and diffusion. These height distributions are in excellent agreement with the measured profiles. Finally, we discuss mesospheric green-line fluctuations and show that good agreement can be obtained for the storm conditions if small adjustments are made to the eddy diffusion coefficients in the mesosphere, which we associate with the passage of the gravity wave. However, we find that some green-line behavior during quiet-time conditions is difficult to explain.
BibTeX:
@article{Vlasov2005,
  author = {Vlasov, Michael N. and Nicolls, Michael J. and Kelley, Michael C. and Smith, Steven M. and Aponte, Nestor and Gonzalez, Sixto A.},
  title = {Modeling of airglow and ionospheric parameters at Arecibo during quiet and disturbed periods in October 2002},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A7},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2005JA011074},
  doi = {10.1029/2005JA011074}
}
Waldrop LS, Kerr RB, Gonzalez SA, Sulzer MP, Noto J and Kamalabadi F (2005), "Generation of metastable helium and the 1083 nm emission in the upper thermosphere", Journal of Geophysical Research: Space Physics. Vol. 110(A8), pp. n/a-n/a.
BibTeX:
@article{Waldrop2005,
  author = {Waldrop, L. S. and Kerr, R. B. and Gonzalez, S. A. and Sulzer, M. P. and Noto, J. and Kamalabadi, F.},
  title = {Generation of metastable helium and the 1083 nm emission in the upper thermosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2005},
  volume = {110},
  number = {A8},
  pages = {n/a-n/a},
  doi = {10.1029/2004JA010855}
}
Wen C-H, Doherty J, Mathews J and Janches D (2005), "Meteor detection and non-periodic bursty interference removal for Arecibo data", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 67(3), pp. 275-281.
BibTeX:
@article{Wen2005,
  author = {C.-H. Wen and J.F. Doherty and J.D. Mathews and D. Janches},
  title = {Meteor detection and non-periodic bursty interference removal for Arecibo data},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2005},
  volume = {67},
  number = {3},
  pages = {275-281},
  doi = {10.1016/j.jastp.2004.10.004}
}
Wen CH, Doherty JF and Mathews J (2005), "Adaptive filtering for the separation of incoherent scatter and meteor signals for Arecibo observation data", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 67(13), pp. 1190-1195.
BibTeX:
@article{Wen2005a,
  author = {Wen, C H and Doherty, J F and Mathews, J},
  title = {Adaptive filtering for the separation of incoherent scatter and meteor signals for Arecibo observation data},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2005},
  volume = {67},
  number = {13},
  pages = {1190-1195},
  doi = {10.1016/j.jastp.2005.06.004}
}
Zhang S-R, Holt JM, van Eyken AP, McCready M, Amory-Mazaudier C, Fukao S and Sulzer M (2005), "Ionospheric local model and climatology from long-term databases of multiple incoherent scatter radars", Geophysical Research Letters. Vol. 32(20), pp. n/a-n/a.
BibTeX:
@article{Zhang2005,
  author = {Zhang, Shun-Rong and Holt, John M. and van Eyken, Anthony P. and McCready, Mary and Amory-Mazaudier, Christine and Fukao, Shoichiro and Sulzer, Michael},
  title = {Ionospheric local model and climatology from long-term databases of multiple incoherent scatter radars},
  journal = {Geophysical Research Letters},
  year = {2005},
  volume = {32},
  number = {20},
  pages = {n/a-n/a},
  doi = {10.1029/2005GL023603}
}
Zhou QH and Morton YT (2005), "Incoherent scatter radar study of photochemistry in the E-region", Geophysical Research Letters. Vol. 32(1), pp. n/a-n/a.
BibTeX:
@article{Zhou2005,
  author = {Zhou, Qihou H. and Morton, Yu T.},
  title = {Incoherent scatter radar study of photochemistry in the E-region},
  journal = {Geophysical Research Letters},
  year = {2005},
  volume = {32},
  number = {1},
  pages = {n/a-n/a},
  doi = {10.1029/2004GL021275}
}
Zhou Q, Friedman J, Raizada S, Tepley C and Morton YT (2005), "Morphology of nighttime ion, potassium and sodium layers in the meteor zone above Arecibo", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 67(13), pp. 1245-1257.
BibTeX:
@article{Zhou2005a,
  author = {Qihou Zhou and Jonathan Friedman and Shikha Raizada and Craig Tepley and Yu T. Morton},
  title = {Morphology of nighttime ion, potassium and sodium layers in the meteor zone above Arecibo},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2005},
  volume = {67},
  number = {13},
  pages = {1245-1257},
  doi = {10.1016/j.jastp.2005.06.013}
}
Bernhardt PA and Sulzer MP (2004), "Incoherent scatter measurements of ring-ion beam distributions produced by space shuttle exhaust injections into the ionosphere", Journal of Geophysical Research: Space Physics. Vol. 109(A2), pp. n/a-n/a.
Abstract: When the space shuttle Orbiting Maneuver Subsystem (OMS) engines burn in the ionosphere, two types of effects are produced. First, charge exchange between the exhaust molecules and the ambient O+-ions yields beams of high-speed molecular ions that can excite plasma turbulence. Second, the molecular ions eventually recombine with electrons to yield a plasma hole. The ion-beam interactions and the formation of artificial plasma holes in the ionosphere have been studied with ground-based, incoherent-scatter radars (ISRs) during the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) series of experiments. The SIMPLEX II experiment took place in late July 1999 during the STS-93 flight of the Space Shuttle Columbia. The Orbital Maneuver Subsystem (OMS) engines provided controlled ion injections over the incoherent scatter radar (ISR) facilities located at Arecibo, Puerto Rico to excite unusual radar signatures. After charge exchange between the exhaust and the ambient plasma, pickup ions were produced with velocities near 10 km/s using a ram-burn orientation of the OMS engines relative to the vehicle orbit vector. During the SIMPLEX II experiment, the ISR spectra of the exhaust-modified plasma were obtained for the first time. The formation of ring-ion beam distributions was determined from curve fitting to the radar spectra. These spectra show the presence of the nonthermal ion distributions and enhanced scatter from electrons for thermal ion distributions with elevated ion temperatures. Analysis of the ion distributions in the modified ionosphere indicates that they were unstable and may have quickly generated plasma waves that along with ion-neutral collisions changed the ion-velocity distributions. The observations show that the perpendicular ion speed was rapidly reduced from 10 km/s to about 1 km/s. These observations open up the possibility of conducting a new series of experiments studying ring-ion beam instabilities that occur naturally in the auroral-region ionosphere and artificially in the space shuttle exhaust where there is large relative motion between the ion and neutral species.
BibTeX:
@article{Bernhardt2004,
  author = {Bernhardt, P. A. and Sulzer, M. P.},
  title = {Incoherent scatter measurements of ring-ion beam distributions produced by space shuttle exhaust injections into the ionosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2004},
  volume = {109},
  number = {A2},
  pages = {n/a-n/a},
  doi = {10.1029/2002JA009693}
}
Clemesha BR, Batista PP, Simonich DM and Batista IS (2004), "Sporadic structures in the atmospheric sodium layer", Journal of Geophysical Research: Atmospheres. Vol. 109(D11), pp. n/a-n/a.
Abstract: The sporadic occurrence of layers of enhanced concentration of meteoric metals in the vicinity of the mesopause has been observed by lidar at many locations. These layers are much thinner than the background layer, last between a few minutes and many hours, and appear to be related to ionospheric sporadic E. A much more rare type of transient layer has been reported in the literature only once, by Kane et al. [2001]. The layers in question, observed in sodium by a lidar operating at Arecibo (18.3°N, 66.7°W), appear as C-shaped structures in the lidar height/time display. The structures, which have been observed at around 100 km, with durations around 30 min, appear not to be related to normal sporadic metals layers, and the Arecibo workers suggest that they might be produced by wave-breaking or Kelvin-Helmholtz billows. At SÖo JosÈ dos Campos (23°S, 46°W) we observe C-structures in the sodium layer only very occasionally, but an analysis of their formation, together with simultaneous meteor winds measurements, suggests that the observed structures might be the result of wind-shear distortion of preexisting clouds of enhanced sodium concentration.
BibTeX:
@article{Clemesha2004,
  author = {Clemesha, Barclay R. and Batista, Paulo P. and Simonich, Dale M. and Batista, Inez S.},
  title = {Sporadic structures in the atmospheric sodium layer},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2004},
  volume = {109},
  number = {D11},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003JD004496},
  doi = {10.1029/2003JD004496}
}
Djuth FT, Sulzer MP, Gonzalez SA, Mathews JD, Elder JH and Walterscheid RL (2004), "A continuum of gravity waves in the Arecibo thermosphere?", Geophysical Research Letters. Vol. 31(16), pp. n/a-n/a.
Abstract: Previous incoherent radar studies at Arecibo Observatory, Puerto Rico have demonstrated that ~1–3% electron density “imprints” of internal gravity waves are routinely present in the Arecibo thermosphere (?118–500 km). A special radar technique involving photoelectron-enhanced plasma waves (PEPWs) was used for these observations. Recently, it was discovered that the trails of the gravity waves can be detected in standard incoherent scatter power profiles when properly filtered. This result was validated using simultaneous PEPW observations. This new development opens up the possibility of monitoring thermospheric gravity waves day and night. Preliminary studies indicate that gravity waves are continually propagating through the Arecibo thermosphere, and that “sets” of waves separated by approximately 20–60 min are typically present. With the aid of additional radar tests, it may be possible to unlock Arecibo power profiles recorded over the past 30 years for gravity wave studies. The precise origin of the waves is currently unknown.
BibTeX:
@article{Djuth2004,
  author = {Djuth, F. T. and Sulzer, M. P. and Gonzalez, S. A. and Mathews, J. D. and Elder, J. H. and Walterscheid, R. L.},
  title = {A continuum of gravity waves in the Arecibo thermosphere?},
  journal = {Geophysical Research Letters},
  year = {2004},
  volume = {31},
  number = {16},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003GL019376},
  doi = {10.1029/2003GL019376}
}
Gonzalez SA, Sulzer MP, Nicolls MJ and Kerr RB (2004), "Solar cycle variability of nighttime topside helium ion concentrations over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 109(A7), pp. n/a-n/a.
Abstract: The incoherent scatter radar mode and data extraction method used in topside experiments at the Arecibo Observatory are discussed. Helium ion concentrations in the lower topside ionosphere over Arecibo are presented for low and high solar flux periods of the same season (October). Data from 8-9 October 1988, 21-22 October 1995, 26-27 October 1997, and 12-13 October 2001 are compared. The data from October 1988 and 2001 are representative of high solar flux conditions, while the other two periods (1995 and 1997) are from low solar flux conditions. All data sets represent geomagnetic quiet periods over Arecibo and serve as examples of typical equinox topside conditions. For solar minimum the altitude distribution of the helium ions usually has a maximum near the O+ to H+ transition altitude (ht) during the night, usually around 550-650 km. The He+ number densities tend to be quite low, 2 or 3 â 103 cm-3 or <15% of the topside plasma density at the peak of the layer. For the higher solar flux case, however, He+ forms a more distinct layer at an altitude that is slightly above at night. The O+-to-He+ transition altitude (ht) is reported to be below after the postsunset collapse in these solar-maximum conditions, meaning that He+ is the dominant species. We find that the relative abundance of He+ can reach 60-65% of the topside plasma at the peak of this layer during these equinox conditions or up to 4 â 104 cm-3, with as low as 700 km and the He+ to H+ transition (ht) extending over 1000 km at night.
BibTeX:
@article{Gonzalez2004,
  author = {Gonzalez, Sixto A. and Sulzer, Michael P. and Nicolls, Michael J. and Kerr, Robert B.},
  title = {Solar cycle variability of nighttime topside helium ion concentrations over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2004},
  volume = {109},
  number = {A7},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003JA010100},
  doi = {10.1029/2003JA010100}
}
Nicolls MJ, Kelley MC, Coster AJ, GonzÀlez SA and Makela JJ (2004), "Imaging the structure of a large-scale TID using ISR and TEC data", Geophysical Research Letters. Vol. 31(9), pp. n/a-n/a.
Abstract: Here we present North American observations of the 3-dimensional structure of large-scale traveling ionospheric disturbances (TIDs) that affected the low- and mid-latitude ionosphere during the stormtime period of October 1–2, 2002. Using TEC data from the American network of dual-frequency GPS receivers, we are able to examine the effect of the TIDs on the background TEC and thus image their horizontal scales. Incoherent scatter radar data from the Arecibo Observatory give information on the vertical structure of the disturbances. The meridional and zonal structure of the TIDs are explored by computing the TEC perturbation, a method which has a resolution of a fraction of a TEC unit. The technique is effective in mapping the global structure of large-scale disturbances, as the lower latitude perturbations can be examined at the same time as the higher latitude sources. The method may prove valuable in studying the formation and propagation of TIDs.
BibTeX:
@article{GRL:GRL18232,
  author = {Nicolls, Michael J. and Kelley, Michael C. and Coster, Anthea J. and GonzÀlez, Sixto A. and Makela, Jonathan J.},
  title = {Imaging the structure of a large-scale TID using ISR and TEC data},
  journal = {Geophysical Research Letters},
  year = {2004},
  volume = {31},
  number = {9},
  pages = {n/a--n/a},
  url = {http://dx.doi.org/10.1029/2004GL019797},
  doi = {10.1029/2004GL019797}
}
Hoffner J and Friedman JS (2004), "The mesospheric metal layer topside: a possible connection to meteoroids", Atmospheric Chemistry and Physics. Vol. 4, pp. 801-808.
BibTeX:
@article{Hoffner2004,
  author = {Hoffner, J and Friedman, J S},
  title = {The mesospheric metal layer topside: a possible connection to meteoroids},
  journal = {Atmospheric Chemistry and Physics},
  year = {2004},
  volume = {4},
  pages = {801-808},
  doi = {10.5194/acp-4-801-2004}
}
Hysell DL, Larsen MF and Zhou QH (2004), "Common volume coherent and incoherent scatter radar observations of mid-latitude sporadic E-layers and QP echoes", Annales Geophysicae. Vol. 22(9), pp. 3277-3290.
BibTeX:
@article{Hysell2004,
  author = {Hysell, D. L. and Larsen, M. F. and Zhou, Q. H.},
  title = {Common volume coherent and incoherent scatter radar observations of mid-latitude sporadic E-layers and QP echoes},
  journal = {Annales Geophysicae},
  year = {2004},
  volume = {22},
  number = {9},
  pages = {3277-3290},
  doi = {10.5194/angeo-22-3277-2004}
}
Janches D, Nolan MC and Sulzer M (2004), "Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar", Atmospheric Chemistry and Physics. Vol. 4(3), pp. 621-626.
BibTeX:
@article{Janches2004,
  author = {Janches, D. and Nolan, M. C. and Sulzer, M.},
  title = {Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar},
  journal = {Atmospheric Chemistry and Physics},
  year = {2004},
  volume = {4},
  number = {3},
  pages = {621-626},
  doi = {10.5194/acp-4-621-2004}
}
Kafando P and Petitdidier M (2004), "An attempt to calibrate the UHF strato-tropospheric radar at Arecibo using NexRad radar and disdrometer data", Annales Geophysicae. Vol. 22(12), pp. 4025-4034.
Abstract: The goal of this paper is to present a methodology to calibrate the reflectivity of the UHF Strato-Tropospheric (ST) radar located at NAIC in Puerto Rico. The UHF lower relevant altitude is at 5.9km, the melting layer being at around 4.8km. The data used for the calibration came from the observations of clouds, carried out with Strato-Tropospheric dual-wavelength (UHF and VHF) radars and a disdrometer; those instruments being located on the NAIC site in Arecibo, Puerto Rico. The National Weather Service operates other instruments like the radiosondes and the NexRad Radar in other sites.

The proposed method proceeds in two steps. The first consists of the comparison between the NexRad reflectivity and the reflectivity computed from the drop size distributions measured by the disdrometer for one day with a noticeable rainfall rate. In spite of the distance of both instruments, the agreement between the reflectivities of both instruments is enough good to be used as a reference for the UHF ST radar. The errors relative at each data set is found to be 2.75dB for the disdrometer and 4dB for the NexRad radar, following the approach of Hocking et al. (2001). The inadequacy between the two sampled volume is an important contribution in the errors.

The second step consists of the comparison between the NexRad radar reflectivity and the UHF non-calibrated reflectivity at the 4 altitudes of common observations during one event on 15 October 1998. Similar features are observed and a coefficient is deduced. An offset around 4.7dB is observed and the correlation factor lies between 0.628 and 0.730. According to the errors of the data sets, the precision on the calibration is of the order of 2dB. This method works only when there are precipitation hydrometeors above the NAIC site. However, the result of the calibration could be applied to other data obtained during the campaign, the only constraint being the same value of the transmitter power.

BibTeX:
@article{Kafando2004a,
  author = {Kafando, P. and Petitdidier, M.},
  title = {An attempt to calibrate the UHF strato-tropospheric radar at Arecibo using NexRad radar and disdrometer data},
  journal = {Annales Geophysicae},
  year = {2004},
  volume = {22},
  number = {12},
  pages = {4025-4034},
  url = {www.ann-geophys.net/22/4025/2004/},
  doi = {10.5194/angeo-22-4025-2004}
}
Kelley MC, Swartz WE and Makela JJ (2004), "Mid-latitude ionospheric fluctuation spectra due to secondary instabilities", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 66(17), pp. 1559 - 1565.
Abstract: The most spectacular night of mid-latitude spread F ever recorded at Arecibo is analyzed and compared with barium cloud observations made in the 1970s and with equatorial spread F. Strong evidence is found for a secondary instability driven either by a poleward electric field and a westward density gradient (both presumably due to a primary Perkins instability), or by a zero-order eastward wind flowing across the westward gradient. Spectra computed from the incoherent scatter density profiles of this event are very similar to the spectra of both barium striations and equatorial spread F. Estimates of the strength of the radar wave scattering expected from the fluctuation spectra are in good agreement with the VHF observations from that night. Finally, a poleward-surging, mid-latitude plasma bubble is seen to bifurcate in a manner similar to equatorial spread-F simulations.
BibTeX:
@article{Kelley2004,
  author = {Michael C. Kelley and Wesley E. Swartz and Jonathan J. Makela},
  title = {Mid-latitude ionospheric fluctuation spectra due to secondary instabilities},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2004},
  volume = {66},
  number = {17},
  pages = {1559 - 1565},
  note = {40 Years of Equatorial Aeronomy Sparked by the Jicamarca Radio Observatory },
  url = {http://www.sciencedirect.com/science/article/pii/S1364682604001610},
  doi = {10.1016/j.jastp.2004.07.004}
}
Kuo SP (2004), "On the cascade spectrum of Langmuir waves observed in Arecibo heating experiments", Physica Scripta. Vol. 69(2), pp. 115-119.
Abstract: Two parametric instabilities cascading Langmuir waves, which are the sideband of the parametric decay instability (PDI) excited by an O-mode HF heating wave, are studied. The first one decays a Langmuir pump wave into a Langmuir sideband and an ion acoustic wave. Both resonant and nonresonant cascade processes are considered. A nonresonant cascade of Langmuir waves proceeds at the same location and is severely hampered by the frequency mismatch effect. Resonant cascade takes place in different resonant locations to minimize the frequency mismatch effect, but it has to overcome the propagation loss of the mother Langmuir wave in each cascade step. Depending on the propagation loss, the resonant cascade could have a lower threshold, but cascade lines spread over a height region. The second one is a three-dimensional coupling process that employs the lower hybrid wave as the decay mode. Through this process, the nonresonant cascade of Langmuir waves produces a broad spectrum of frequency-downshifted plasma waves, similar to that of experimentally observed HFPLs, in a narrow altitude range, which is preferentially located near the matching height of the PDI sideband.
BibTeX:
@article{Kuo_2004,
  author = {Kuo, S. P.},
  title = {On the cascade spectrum of Langmuir waves observed in Arecibo heating experiments},
  journal = {Physica Scripta},
  year = {2004},
  volume = {69},
  number = {2},
  pages = {115-119},
  url = {http://iopscience.iop.org/1402-4896/69/2/007},
  doi = {10.1238/Physica.Regular.069a00115}
}
Larsen MF, Liu AZ, Gardner CS, Kelley MC, Collins S, Friedman J and Hecht JH (2004), "Observations of overturning in the upper mesosphere and lower thermosphere", Journal of Geophysical Research: Atmospheres. Vol. 109(D2), pp. n/a-n/a.
Abstract: A number of observations of the sodium density primarily in the mesosphere and lower thermosphere (but also of the electron density structure) have shown what appears to be overturning or convective roll cells near the transition from the mesosphere to the lower thermosphere. The cells are found in the region between 95 and 105 km and occur near the boundary between the region of lower stability in the mesosphere and the region of higher stability in the lower thermosphere. The vertical scale for the rolls is ~5–6 km, and the timescale is ~1–3 hours. The rolls occur in a region characterized by large shear in the neutral winds, but the timescales are too long to be explained by simple Kelvin-Helmholtz instability. We present observations from the University of Illinois lidar facility located at the Starfire Optical Range near Albuquerque, New Mexico, from the Arecibo Observatory in Puerto Rico, and from the Maui/MALT Lidar Facility located on Maui in Hawaii that show the overturning structure. possible mechanisms for generating the convective rolls are discussed, Including the relationship of the observed features to the characteristics expected for an inflection point instability.
BibTeX:
@article{Larsen2004,
  author = {Larsen, M. F. and Liu, A. Z. and Gardner, C. S. and Kelley, M. C. and Collins, S. and Friedman, J. and Hecht, J. H.},
  title = {Observations of overturning in the upper mesosphere and lower thermosphere},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2004},
  volume = {109},
  number = {D2},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2002JD003067},
  doi = {10.1029/2002JD003067}
}
Lobzin VV and Pavlov AV (2004), "Relation of the Electron Temperature to the Concentrations of the Electrons and Neutral Components in the Daytime Ionosphere over Arecibo Station", International Journal of Geomagnetism and Aeronomy. Vol. 44(4), pp. 453-460.
BibTeX:
@article{Lobzin2004,
  author = {Lobzin, V. V. and Pavlov, A. V.},
  title = {Relation of the Electron Temperature to the Concentrations of the Electrons and Neutral Components in the Daytime Ionosphere over Arecibo Station},
  journal = {International Journal of Geomagnetism and Aeronomy},
  year = {2004},
  volume = {44},
  number = {4},
  pages = {453-460}
}
Love A (2004), "Arecibo Observatory 40th anniversary celebration", IEEE Antennas and Propagation Magazine. Vol. 46(1), pp. 94-97.
Abstract: The National Astronomy and Ionosphere Center (NAIC), operated by Cornell University for the National Science Foundation, has its laboratory at Arecibo in Puerto Rico. The observatory's main instrument is a radio/radar telescope that utilizes a giant reflector antenna 1,000 feet in diameter, the largest in the world by considerable margin. A 40th anniversary celebration of the 1963 inauguration of this observatory was held at the site in Puerto Rico on November 1, 2003. This paper discusses the development of the said antenna, its characteristics and the upgrading of the system. The paper includes a discussion of what transpired during the said anniversary celebration.
BibTeX:
@article{Love2004,
  author = {Love, A.W.},
  title = {Arecibo Observatory 40th anniversary celebration},
  journal = {IEEE Antennas and Propagation Magazine},
  year = {2004},
  volume = {46},
  number = {1},
  pages = {94-97},
  url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1296152},
  doi = {10.1109/MAP.2004.1296152}
}
Murad E and Roth C (2004), "Evaporation of high speed sporadic meteors", Atmospheric Chemistry and Physics. Vol. 4(3), pp. 737-740.
BibTeX:
@article{Murad2004,
  author = {Murad, E. and Roth, C.},
  title = {Evaporation of high speed sporadic meteors},
  journal = {Atmospheric Chemistry and Physics},
  year = {2004},
  volume = {4},
  number = {3},
  pages = {737-740},
  doi = {10.5194/acp-4-737-2004}
}
Pandey V, Sethi N and Mahajan K (2004), "Topside electron temperature models for low and high solar activity ", Advances in Space Research . Vol. 33(6), pp. 959-962.
BibTeX:
@article{Pandey2004,
  author = {V.K. Pandey and N.K. Sethi and K.K. Mahajan},
  title = {Topside electron temperature models for low and high solar activity },
  journal = {Advances in Space Research },
  year = {2004},
  volume = {33},
  number = {6},
  pages = {959-962},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117703010238},
  doi = {10.1016/j.asr.2003.07.011}
}
Pavlov AV, Fukao S and Kawamura S (2004), "Comparison of the measured and modeled electron densities, and electron and ion temperatures in the low-latitude ionosphere during 19-21 March 1988", Annales Geophysicae. Vol. 22(8), pp. 2747-2763.
BibTeX:
@article{Pavlov2004,
  author = {Pavlov, A. V. and Fukao, S. and Kawamura, S.},
  title = {Comparison of the measured and modeled electron densities, and electron and ion temperatures in the low-latitude ionosphere during 19-21 March 1988},
  journal = {Annales Geophysicae},
  year = {2004},
  volume = {22},
  number = {8},
  pages = {2747-2763},
  doi = {10.5194/angeo-22-2747-2004}
}
Pavlov AV, Fukao S and Kawamura S (2004), "F-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987", Annales Geophysicae. Vol. 22(10), pp. 3479-3501.
BibTeX:
@article{Pavlov2004a,
  author = {Pavlov, A. V. and Fukao, S. and Kawamura, S.},
  title = {F-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987},
  journal = {Annales Geophysicae},
  year = {2004},
  volume = {22},
  number = {10},
  pages = {3479-3501},
  doi = {10.5194/angeo-22-3479-2004}
}
Raizada S, Tepley C, Janches D, Friedman J, Zhou Q and Mathews J (2004), "Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 66, pp. 595-606.
BibTeX:
@article{Raizada2004,
  author = {S. Raizada and C.A. Tepley and D. Janches and J.S. Friedman and Q. Zhou and J.D. Mathews},
  title = {Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2004},
  volume = {66},
  pages = {595-606},
  doi = {10.1016/j.jastp.2004.01.030}
}
Rodrigues FS, Brum CGM, Makita K, Nishino M, Paula ERd, Abdu MA, Nozaki K, Contreira DB, Silva MRd and Schuch NJ (2004), "A commercial radio receiver for lower ionosphere monitoring: Initial results", Geofisica Internacional. Vol. 43, pp. 193-198.
Abstract: A commercial computer controlled radio receiver has been used to measure signal strength of High Frequency (HF) signals in order to study the effects of geophysical events on radio communications and to test the system for ionospheric monitoring. The system was installed at the Southern Space Observatory (OES/CRSPE/INPE) in SÖo Martinho da Serra, Brazil (29.43S, 53.8W, B = 23350 nT). Initial results show that this system is able to detect ionospheric radio absorption events. The commercial radio receiver has a computer serial interface, to control the reception frequency in order to acquire the values of the received signal strength. We describe the system and some initial results on radio absorption events associated to C and M classes of x-ray solar flares. The results suggest the possibility of using this low-cost system to study the daily variation of the lower ionosphere ionization and to study events of ionospheric absorption. Long period measurements give statistical information about the magnitude and time scale of fading, that can be used for planning radio links.
BibTeX:
@article{Rodrigues2004,
  author = {Rodrigues, F S and Brum, C G M and Makita, K and Nishino, M and Paula, E R de and Abdu, M A and Nozaki, K and Contreira, D B and Silva, M R da and Schuch, N J},
  title = {A commercial radio receiver for lower ionosphere monitoring: Initial results},
  journal = {Geofisica Internacional},
  year = {2004},
  volume = {43},
  pages = {193-198},
  note = {Arecibo author},
  url = {http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/2004/02/Rodrigues.pdf}
}
Rosado-Roman JM, Swartz WE and Farley DT (2004), "Plasma instabilities observed in the E region over Arecibo and a proposed nonlocal theory", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 66(17), pp. 1593-1602.
BibTeX:
@article{Rosado-Roman2004,
  author = {Jose M. Rosado-Roman and Wesley E. Swartz and Donald T. Farley},
  title = {Plasma instabilities observed in the E region over Arecibo and a proposed nonlocal theory},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2004},
  volume = {66},
  number = {17},
  pages = {1593-1602},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682604001622},
  doi = {10.1016/j.jastp.2004.07.005}
}
Sethi N, Pandey V and Mahajan K (2004), "Seasonal and solar activity changes of electron temperature in the F-region and topside ionosphere", Advances in Space Research. Vol. 33(6), pp. 970-974.
BibTeX:
@article{Sethi2004,
  author = {N.K Sethi and V.K Pandey and K.K Mahajan},
  title = {Seasonal and solar activity changes of electron temperature in the F-region and topside ionosphere},
  journal = {Advances in Space Research},
  year = {2004},
  volume = {33},
  number = {6},
  pages = {970-974},
  doi = {10.1016/j.asr.2003.08.008}
}
Sulzer MP (2004), "Meteoroid velocity distribution derived from head echo data collected at Arecibo during regular world day observations", Atmospheric Chemistry and Physics. Vol. 4(4), pp. 947-954.
BibTeX:
@article{Sulzer2004,
  author = {Sulzer, M. P.},
  title = {Meteoroid velocity distribution derived from head echo data collected at Arecibo during regular world day observations},
  journal = {Atmospheric Chemistry and Physics},
  year = {2004},
  volume = {4},
  number = {4},
  pages = {947-954},
  doi = {10.5194/acp-4-947-2004}
}
Urbina J, Kudeki E, Franke SJ and Zhou Q (2004), "Analysis of a mid-latitude E-region LQP event observed during the Coqui 2 Campaign", Geophysical Research Letters. Vol. 31(14), pp. n/a-n/a.
Abstract: Arecibo ISR observations and VHF coherent backscatter data collected with a radar situated in southern Puerto Rico are examined to understand the causes of quasi-periodic variations in VHF returns from lower E-region heights (~93 km). It is found that Bragg scale density irregularities causing the observed VHF backscatter are formed and propagated horizontally in a density perturbation field localized at the upper boundary of a tidal ion layer. The density perturbation has a 7 km horizontal wavelength, propagates in southwest direction, and it is not aligned with the geomagnetic field. Thus the production mechanism of the observed density perturbation cannot be the gradient-drift instability often invoked to account for the generation of mid-latitude sporadic E radar echoes. Nevertheless, secondary gradient-drift instability operating on the gradients of the southwest propagating perturbation remains the most likely cause of Bragg scale electron density waves responsible for the VHF returns.
BibTeX:
@article{Urbina2004,
  author = {Urbina, Julio and Kudeki, Erhan and Franke, Steven J. and Zhou, Qihou},
  title = {Analysis of a mid-latitude E-region LQP event observed during the Coqui 2 Campaign},
  journal = {Geophysical Research Letters},
  year = {2004},
  volume = {31},
  number = {14},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2004GL020031},
  doi = {10.1029/2004GL020031}
}
Wen CH, Doherty JF and Mathews JD (2004), "Time-frequency radar processing for meteor detection", IEEE Transactions on Geoscience and Remote Sensing. Vol. 42(3), pp. 501-510.
Abstract: In this paper, we present signal processing techniques to detect meteor returns from Arecibo Observatory 430-MHz UHF radar data. We exploit the characteristics of the transmit waveform in the frequency domain as well as in the time domain. Two detection methods are investigated. First, when a meteor is present in the radar return over several interpulse periods, there will be a periodic structure in frequency spectrum. By detecting this structure, we detect the presence of a meteor. Second, we construct a matched filter bank to detect the energy of different Doppler frequency components. When the energy exceeds a certain threshold, we declare meteor detection. We also find the altitude of a meteor by finding the peak of the matched filter output. Analytical and experimental results show that we can efficiently and reliably detect meteors using these methods.
BibTeX:
@article{Wen2004,
  author = {Wen, C H and Doherty, J F and Mathews, J D},
  title = {Time-frequency radar processing for meteor detection},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  year = {2004},
  volume = {42},
  number = {3},
  pages = {501-510},
  doi = {10.1109/TGRS.2003.821344}
}
Zhang S, Thayer J, Roble R, Salah J, Shepherd G, Goncharenko L and Zhou Q (2004), "Latitudinal variations of neutral wind structures in the lower thermosphere for the March equinox period", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 66(1), pp. 105-117.
Abstract: Neutral winds in the lower thermosphere (95–130 km) measured during the March equinox period (1991–1992) by
ground-based incoherent scatter radars at Arecibo (18oN), Millstone Hill (42:5oN), and Sondrestrom (67oN) and by the
space-based wind imaging interferometer (WINDII) are compared and show overall good agreement but some differences.
At 18oN, the wind field in the altitude region of 95–110 km displays prevailing upward propagating diurnal tides with wavelengths
of about 22 km. The diurnal structure is afected by the semidiurnal tide resulting in regular minima separated by
11–12 h. At altitudes above 110 km, the diurnal tide dominant wind structure changes to the semidiurnal tide dominant structure
as illustrated clearly by WINDII data with 24 h coverage. Winds at 42:5oN and 67oN show similar structures in which
winds at 105–115 km are generally anti-sunward. Daytime ISR winds show prevailing upward propagating semidiurnal tides
with wavelengths of 35–70 km. Winds from WINDII reveal the existence of the in situ thermospheric diurnal tide with amplitudes
comparable to those of the semidiurnal tide. The superimposition of the two tides result in a wind field stronger during
daytime than during nighttime at mid- and high-latitudes. Geomagnetic infuence on neutral winds is negligible at low- and
mid-latitudes under solar quiet conditions, but is observed at high-latitudes, where wind vectors follow a clockwise one-cell
pattern at altitudes above about 118 km in geomagnetic coordinates. Most recent simulations for the three latitudes provided
by the NCAR thermosphere/ionosphere/mesosphere electrodynamics general circulation model are compared to the observations.
The results at low- and mid-latitudes agree well with the observed winds in both wind structures and magnitudes, and
reveal details of wave transition. Simulations for high-latitudes are less satisfactory, and require further improvements.
BibTeX:
@article{Zhang2004,
  author = {S.P. Zhang and J.P. Thayer and R.G. Roble and J.E. Salah and G.G. Shepherd and L.P. Goncharenko and Q.H. Zhou},
  title = {Latitudinal variations of neutral wind structures in the lower thermosphere for the March equinox period},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2004},
  volume = {66},
  number = {1},
  pages = {105-117},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682603002074},
  doi = {10.1016/j.jastp.2003.09.011}
}
Zhou QH, Morton YT, Mathews JD and Janches D (2004), "Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers", Atmospheric Chemistry and Physics. Vol. 4(3), pp. 685-692.
Abstract: The aspect sensitivity of VHF echoes from field aligned irregularities (FAI) within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (pB), substantial power can be obtained off the pB direction if the ionization trail/layer is thin. When the FAI length along B is 20 m, the power observed 6° off pB is about 10 db below that perpendicular to the B direction. Meteoric FAI echoes can potentially be used to determine the diffusion rate in the mesopause region. Based on the aspect sensitivity analysis, we conclude that the range spread trail echoes far off pB observed by powerful VHF radars are likely due to overdense meteors. Our simulation also shows that ionospheric FAI echoes can have an altitude smearing effect of about 4 km if the vertical extension of a FAI-layer is around 100 m, which has often been observed at Arecibo. The altitude smearing effect can account for the fact that the Es-layers observed by the Arecibo incoherent scatter radar are typically much narrower than FAI-layers and the occurrence of double spectral peaks around the Es-layer altitude in FAI echoes.
BibTeX:
@article{Zhou2004,
  author = {Zhou, Q. H. and Morton, Y. T. and Mathews, J. D. and Janches, D.},
  title = {Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers},
  journal = {Atmospheric Chemistry and Physics},
  year = {2004},
  volume = {4},
  number = {3},
  pages = {685-692},
  doi = {10.5194/acp-4-685-2004}
}
Bernhardt PA, Gondarenko NA, Guzdar PN, Djuth FT, Tepley CA, Sulzer MP, Ossakow SL and Newman DL (2003), "Using radio-induced aurora to measure the horizontal structure of ion layers in the lower thermosphere", Journal of Geophysical Research: Space Physics. Vol. 108(A9), pp. n/a-n/a.
Abstract: Two-dimensional images of sporadic E layers have been produced using a technique called radio-induced aurora. This technique makes the ion layer regions glow when being stimulated by high-power radio waves. Normally, the neutral regions near the ion layers do not radiate visible emissions. Experiments in January 1998 at Arecibo Observatory in Puerto Rico have shown that the ion layer regions at 120 km altitude can be made to glow at 557.7 nm and other wavelengths by illuminating them with radio waves at 3.175 MHz with effective radiated powers of 80 MW. The regions of the sporadic E layers that have electron densities greater than the critical density for reflection of the radio waves emit energetic electrons that collide with and excite atmospheric atomic oxygen and molecular nitrogen. Because the electron collisions increase at lower altitudes where the neutral densities are higher, major differences in excitation can occur between layers at 120 km altitude and at 100 km altitude. A charge-coupled device imager located on the ground is used to capture images of the glowing E region structures. The camera exposure times were in the range of 15–45 s. The images obtained using this technique show a wide variety of structures in the sporadic E layers. Some layers cover the 15 â 30 km region illuminated by the radio wave beam. Other layers show strong modulation of the E region by instabilities driven by a shear in the neutral wind. Two-dimensional computer simulations of the coupling between neutral wind turbulence and the ion layers replicate the structure shown in the images. The optical emissions are explained using one- and two-dimensional simulations of radio propagation to produce localized regions of large electric fields. Electrons are accelerated out of these regions yielding the artificial aurora.
BibTeX:
@article{Bernhardt2003,
  author = {Bernhardt, P. A. and Gondarenko, N. A. and Guzdar, P. N. and Djuth, F. T. and Tepley, C. A. and Sulzer, M. P. and Ossakow, S. L. and Newman, D. L.},
  title = {Using radio-induced aurora to measure the horizontal structure of ion layers in the lower thermosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2003},
  volume = {108},
  number = {A9},
  pages = {n/a-n/a},
  doi = {10.1029/2002JA009712}
}
Bishop RL and Earle GD (2003), "Metallic ion transport associated with midlatitude intermediate layer development", Journal of Geophysical Research: Space Physics. Vol. 108(A1), pp. SIA 3-1/SIA 3-8.
Abstract: Although intermediate layers are frequently observed by the Arecibo Incoherent Radar Observatory and by ionosondes around the world, many questions still remain regarding their formation, structure, and composition. In this paper, we explore the effect of metallic ions, specifically Fe+, on intermediate layer development and evolution. Several studies have demonstrated that layers can form from either molecular or metallic ions. This paper extends these earlier studies by quantifying the effect of metallic ions on intermediate layer morphology. We show that the efficiency of metallic ion transport depends significantly on the amplitude and wavelength of the imposed horizontal wind field. Specifically, larger amplitudes and longer wavelengths result in increased ion transport in the direction of the propagating neutral wind field.
BibTeX:
@article{Bishop2003,
  author = {Bishop, R. L. and Earle, G. D.},
  title = {Metallic ion transport associated with midlatitude intermediate layer development},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2003},
  volume = {108},
  number = {A1},
  pages = {SIA 3-1/SIA 3-8},
  doi = {10.1029/2002JA009411}
}
Boyer E, Larzabal P, Adnet C and Petitdidier M (2003), "Parametric spectral moments estimation for wind profiling radar", IEEE Transactions on Geoscience and Remote Sensing. Vol. 41(8), pp. 1859-1868.
Abstract: The purpose of this work is the estimation of Doppler echoes spectral moments. In case of strong overlapping, Fourier-like techniques provide poor results because of the lack of resolution. We propose the use of stochastic maximum-likelihood (SML) and subspace-based methods (WPSF algorithm) for a joint estimation of spectral moments. The statistical performances (theoretical and empirical by Monte Carlo simulations) of estimators are compared with the Cramer-Rao lower bound. The results of tests performed on very high frequency (VHF) times series obtained during Thunderstorm, Arecibo, PR during September and October 1998 validate the model and algorithms and confirm the interest of both approaches.
BibTeX:
@article{Boyer2003,
  author = {Boyer, E. and Larzabal, P. and Adnet, C. and Petitdidier, M.},
  title = {Parametric spectral moments estimation for wind profiling radar},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  year = {2003},
  volume = {41},
  number = {8},
  pages = {1859-1868},
  doi = {10.1109/TGRS.2003.813487}
}
Friedman JS, Tepley CA, Raizada S, Zhou QH, Hedin J and Delgado R (2003), "Potassium Doppler-resonance lidar for the study of the mesosphere and lower thermosphere at the Arecibo Observatory", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 65(16-18), pp. 1411-1424.
BibTeX:
@article{Friedman2003,
  author = {Jonathan S. Friedman and Craig A. Tepley and Shikha Raizada and Qihou H. Zhou and Jonas Hedin and Ruböƒá©n Delgado},
  title = {Potassium Doppler-resonance lidar for the study of the mesosphere and lower thermosphere at the Arecibo Observatory},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2003},
  volume = {65},
  number = {16-18},
  pages = {1411-1424},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682603002050},
  doi = {10.1016/j.jastp.2003.09.004}
}
Friedman JS (2003), "Tropical mesopause climatology over the Arecibo Observatory", Geophysical Research Letters. Vol. 30(12), pp. n/a-n/a.
Abstract: We report on the first annual cycle of mesopause-region (82–105 km) temperature profiles at a tropical latitude site, the Arecibo Observatory (18.35°N, 66.75°W), measured by potassium resonance lidar. Based on 74 night-time temperature profiles of observing periods greater than 5 hours we observe a mean temperature profile with a mesopause altitude of 98 km and temperature of 193 K. The annual mean nighttime temperature profile is similar to that seen at mid-latitudes, but there are striking differences in seasonal structure. The mesopause region mean seasonal structure at Arecibo experiences a temperature minimum of 176 K at 100 km during mid-summer. The winter period minimum of about 190 K is found mostly in a broad flat distribution between 90 and 95 km, and less frequently near 100 km.
BibTeX:
@article{Friedman2003a,
  author = {Friedman, Jonathan S.},
  title = {Tropical mesopause climatology over the Arecibo Observatory},
  journal = {Geophysical Research Letters},
  year = {2003},
  volume = {30},
  number = {12},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003GL016966},
  doi = {10.1029/2003GL016966}
}
Gelinas LJ, Kelley MC, Sulzer MP, Mishin E and Starks MJ (2003), "In situ observations during an HF heating experiment at Arecibo: Evidence for Z-mode and electron cyclotron harmonic effects", Journal of Geophysical Research: Space Physics. Vol. 108(A10), pp. n/a-n/a.
Abstract: On 11 March 1998 the Langmuir Turbulence sounding rocket was launched through the Arecibo heater beam during an experiment to measure electric fields and plasma densities in the heater interaction region. In spite of a serious degradation of the Arecibo heater, the rocket data has provided evidence of Z mode waves and field aligned striations above the O mode reflection height. These observations give credence to the theory that Z mode wave interactions with field-aligned striations may be, in part, responsible for some of the features of the reflected HF spectrum observed in heating experiments. We also find strong low-frequency electric fields where the local plasma frequency matches an electron cyclotron harmonic. This suggests that electron Bernstein modes must be generated in the interaction process and can propagate to regions where they are severely damped.
BibTeX:
@article{Gelinas2003,
  author = {Gelinas, L. J. and Kelley, M. C. and Sulzer, M. P. and Mishin, E. and Starks, M. J.},
  title = {In situ observations during an HF heating experiment at Arecibo: Evidence for Z-mode and electron cyclotron harmonic effects},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2003},
  volume = {108},
  number = {A10},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003JA009922},
  doi = {10.1029/2003JA009922}
}
Lee C-C, Liu J-Y, Pan C-J and Hsu H-H (2003), "The intermediate layers and associated tidal motions observed by a digisonde in the equatorial anomaly region", Annales Geophysicae. Vol. 21(4), pp. 1039-1045.
BibTeX:
@article{Lee2003,
  author = {Lee, C.-C. and Liu, J.-Y. and Pan, C.-J. and Hsu, H.-H.},
  title = {The intermediate layers and associated tidal motions observed by a digisonde in the equatorial anomaly region},
  journal = {Annales Geophysicae},
  year = {2003},
  volume = {21},
  number = {4},
  pages = {1039-1045},
  doi = {10.5194/angeo-21-1039-2003}
}
Lyons WA, CCM, Nelson TE, Armstrong RA, Pasko VP and Stanley MA (2003), "Upward Electrical Discharges From Thunderstorm Tops", Bulletin of the American Meteorological Society. Vol. 84, pp. 445-454.
Abstract: A variety of storm top electrical discharges have been observed using several types of low-light imagers, film, and the human eye. Recently, a video recorded an unprecedented, bright blue upward discharge from a tropical thunderstorm top near Puerto Rico. The event reached the base of the ionosphere. The horizontal dimensions of cloud top discharges can range from 100 m to several kilometers. Upward extents vary from 100 m to 70 km. Shapes include “points” of light, upwardly flaring trumpets, and narrow, vertical, lightning-like channels, some topped with expanding blue, flame-like features. Visual appearances range from brilliant white lightning-like channels to a grainy, almost particulate appearing jets of dim blue light, and sometimes as a blue flame within which a brilliant white channel appears. The classical blue jet is at the lower limit of human night vision whereas some upward discharges have been clearly seen during daylight. Cloud top “pixies” last no longer than 16.7 ms, whereas upward lightning-like channels are often characterized as long lasting (2.0 s or more). To date, optical measurements have not associated cloudtop events with specific lightning flashes. There is a strong tendency for all such events to occur above the convective dome of rapidly intensifying thunderstorms. It is possible that the great diversity of forms illustrates the complexity inherent in the upward streamer mechanism for blue jets. It is also possible that the basic blue jet is only one of several distinct classes of discharges from highly electrified storm cloud tops. Future research should focus on rapidly growing convective storm tops, including supercells and intense oceanic storms, as opposed to the stratiform regions of large mesoscale convective systems that have characterized sprite observations to date.
BibTeX:
@article{Lyons2003,
  author = {Walter A. Lyons and CCM and Thomas E. Nelson and Russell A. Armstrong and Victor P. Pasko and Mark A. Stanley},
  title = {Upward Electrical Discharges From Thunderstorm Tops},
  journal = {Bulletin of the American Meteorological Society},
  year = {2003},
  volume = {84},
  pages = {445-454},
  url = {http://dx.doi.org/10.1175/BAMS-84-4-445}
}
Makela JJ, Kelley MC, Gonzalez SA, Aponte N and Sojka JJ (2003), "Mid-latitude plasma and electric field measurements during space weather month, September 1999", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 65, pp. 1077-1085.
Abstract: Using data collected during the September 1999 combined ionospheric campaign (CIC), we examine the effects of moderate geomagnetic activity on low and mid-latitudes. Perturbations in the zonal electric field, measured at both Jicamarca and Arecibo, are the most striking aspect of this data. These eastward electric fields resulted in a poleward advection of the Appleton anomaly to mid-latitudes, where it was observed as a gradient in the nighttime electron density, as measured by the Arecibo incoherent scatter radar. This gradient was severe enough that it was observable in airglow measurements at 630.0 and 777.4nm. To put this data into context, we also examine the worldwide conditions during this time period and find evidence for several substorms, penetrating electric fields, and disturbance dynamo electric fields.
BibTeX:
@article{Makela2003,
  author = {Makela, J. J. and Kelley, M. C. and Gonzalez, S. A. and Aponte, N. and Sojka, J. J.},
  title = {Mid-latitude plasma and electric field measurements during space weather month, September 1999},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2003},
  volume = {65},
  pages = {1077-1085},
  url = {http://dx.doi.org/10.1016/j.jastp.2003.07.002},
  doi = {10.1016/j.jastp.2003.07.002}
}
Mathews J D and. Doherty J, Wen CH, Briczinski SJ, Janches D and Meisel DD (2003), "An update on UHF radar meteor observations and associated signal processing techniques at Arecibo Observatory", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 65(10), pp. 1139-1149.
BibTeX:
@article{Mathews2003,
  author = {Mathews, J D and. Doherty, J and Wen, C H and Briczinski, S J and Janches, D and Meisel, D D},
  title = {An update on UHF radar meteor observations and associated signal processing techniques at Arecibo Observatory},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2003},
  volume = {65},
  number = {10},
  pages = {1139-1149},
  doi = {10.1016/j.jastp.2003.07.009}
}
Pandey V, Sethi N and Mahajan K (2003), "Dependence of F2- peak height on solar activity: A study with incoherent scatter measurements", Advances in Space Research . Vol. 31(3), pp. 543-548.
Abstract: We have used about 16000 high resolution electron density profiles from Arecibo (18.4 N, 66.7 W, dip 50°) incoherent scatter radar for the years 1974–1977 and 1989–1990 to study the control of solar activity on the F2 peak height (hmF2). Although the general trend of diurnal variations in hmF2 are nearly identical (i.e. maximum around midnight and minimum around sunrise) during low as well as high solar activity, the median hmF2 increases by about 100 km from solar minimum to solar maximum. Further, there is a considerable day-to-day variability in hmF2. Comparison of measured hmF2 with the IRI (derived from numerical map of M(3000)F2) reveals that IRI generally overestimates this parameter during low solar activity and underestimates during high solar activity.
BibTeX:
@article{Pandey2003,
  author = {V.K. Pandey and N.K. Sethi and K.K. Mahajan},
  title = {Dependence of F2- peak height on solar activity: A study with incoherent scatter measurements},
  journal = {Advances in Space Research },
  year = {2003},
  volume = {31},
  number = {3},
  pages = {543-548},
  url = {http://www.sciencedirect.com/science/article/pii/S0273117703000498},
  doi = {10.1016/S0273-1177(03)00049-8}
}
Raizada S and Tepley CA (2003), "Seasonal variation of mesospheric iron layers at Arecibo: First results from low-latitudes", Geophysical Research Letters. Vol. 30(2), pp. n/a-n/a.
Abstract: We present the annual variation of the distribution of neutral iron of the low-latitude mesopause region measured at the Arecibo Observatory using resonance fluorescence lidar. A comparison was made between our low-latitude measurements and similar mid-and high-latitude observations of Fe column abundance, centroid height, and RMS width of the layer. We find that the annual variation of the height and width of the layer are essentially anti-correlated with previous measurements, while the column abundance lags its midlatitude counterpart by roughly three months. We suggest that the latitudinal differences in Fe layer properties result from variations in the distribution of mesospheric ozone and O2, which in turn affect the iron chemistry at the two latitudes.
BibTeX:
@article{Raizada2003,
  author = {Raizada, Shikha and Tepley, Craig A.},
  title = {Seasonal variation of mesospheric iron layers at Arecibo: First results from low-latitudes},
  journal = {Geophysical Research Letters},
  year = {2003},
  volume = {30},
  number = {2},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2002GL016537},
  doi = {10.1029/2002GL016537}
}
Sojka JJ, Thompson DC, Schunk RW, Eccles JV, Makela JJ, Kelley MC, Gonzalez SA, Aponte N and Bullett TW (2003), "Ionospheric data assimilation: recovery of strong mid-latitudinal density gradients", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 65(10), pp. 1087-1097.
BibTeX:
@article{Sojka2003,
  author = {Sojka, J J and Thompson, D C and Schunk, R W and Eccles, J V and Makela, J J and Kelley, M C and Gonzalez, S A and Aponte, N. and Bullett, T W},
  title = {Ionospheric data assimilation: recovery of strong mid-latitudinal density gradients},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2003},
  volume = {65},
  number = {10},
  pages = {1087-1097},
  doi = {10.1016/j.jastp.2003.07.004}
}
Tepley CA, Raizada S, Zhou Q and Friedman JS (2003), "First simultaneous observations of Ca+, K, and electron density using lidar and incoherent scatter radar at Arecibo", Geophysical Research Letters. Vol. 30(1), pp. 9-1/9-4.
Abstract: We report the first measurements of Ca+ made from the Arecibo Observatory achieved by using a frequency-agile resonance fluorescence lidar. Simultaneous observations of the electron concentration of the lower ionosphere using the Arecibo incoherent scatter radar were also made, as well as K lidar observations of the mesospause region. We find excellent agreement in the distribution of ions observed between the lidar and radar for both the thin tidal ion layers and for broader formations of ionization that occasionally occur near 90 km altitude. The concentration of Ca+ within ion layers was found to be slightly less than the relative fraction of calcium in meteors, and generally consistent with previous lidar, rocket, and twilight airglow measurements.
BibTeX:
@article{Tepley2003,
  author = {Tepley, Craig A. and Raizada, Shikha and Zhou, Qihou and Friedman, Jonathan S.},
  title = {First simultaneous observations of Ca+, K, and electron density using lidar and incoherent scatter radar at Arecibo},
  journal = {Geophysical Research Letters},
  year = {2003},
  volume = {30},
  number = {1},
  pages = {9-1/9-4},
  url = {http://dx.doi.org/10.1029/2002GL015927},
  doi = {10.1029/2002GL015927}
}
Tepley CA, Raizada S, Zhou Q and Friedman JS (2003), "Correction to “First simultaneous observations of Ca+, K, and electron density using lidar and incoherent scatter radar at Arecibo”", Geophysical Research Letters. Vol. 30(6), pp. n/a-n/a.
BibTeX:
@article{Tepley2003a,
  author = {Tepley, Craig A. and Raizada, Shikha and Zhou, Qihou and Friedman, Jonathan S.},
  title = {Correction to “First simultaneous observations of Ca+, K, and electron density using lidar and incoherent scatter radar at Arecibo”},
  journal = {Geophysical Research Letters},
  year = {2003},
  volume = {30},
  number = {6},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003GL017188},
  doi = {10.1029/2003GL017188}
}
Titheridge JE (2003), "Ionisation below the night F2 layer - a global model", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 65(9), pp. 1035-1052.
BibTeX:
@article{Titheridge2003,
  author = {Titheridge, J E},
  title = {Ionisation below the night F2 layer - a global model},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2003},
  volume = {65},
  number = {9},
  pages = {1035-1052},
  doi = {10.1016/S1364-6826(03)00136-6}
}
Vlasov MN, Kelley MC, Makela JJ and Nicolls MJ (2003), "Intense nighttime flux from the plasmasphere during a modest magnetic storm", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 65(10), pp. 1099 - 1105.
Abstract: An analytical-numerical model is created for two nights during Space Weather Month in September 1999. On one of these nights, after the midnight collapse over the Arecibo Observatory, the plasma density remained quite high in spite of a very sharp decrease in the F2 peak height. In order to support this high density against recombination, a very high plasma flux from the plasmasphere, a value of about 6â1e8cm-2s-1, is needed. Initially, data assimilation attempts did not allow such a flux (see Ionospheric data assimilation: recovery of strong mid-latitudinal density gradients, J. Atmos. Sol.-Terr. Phys., this issue). We believe the high flux results from a well-developed equatorial fountain and an Appleton anomaly well north of its usual location. The latter is consistent with both the large plasma gradient over Arecibo and the enhanced Jicamarca electric field (see Midlatitude plasma and electric field measurements during Space Weather Month, September 1999. J. Atmos. Sol.-Terr. Phys., this issue).
BibTeX:
@article{Vlasov2003,
  author = {Michael N. Vlasov and Michael C. Kelley and Jonathan J. Makela and Michael J. Nicolls},
  title = {Intense nighttime flux from the plasmasphere during a modest magnetic storm},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2003},
  volume = {65},
  number = {10},
  pages = {1099 - 1105},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682603001640},
  doi = {10.1016/j.jastp.2003.07.003}
}
Wilford CR, Moffett RJ, Rees JM, Bailey GJ and Gonzalez SA (2003), "Comparison of the He+ layer observed over Arecibo during solar maximum and solar minimum with CTIP model results", Journal of Geophysical Research: Space Physics. Vol. 108(A12), pp. n/a-n/a.
Abstract: Light ion concentration observations from the Arecibo incoherent scatter radar have shown regions of He+ layering in the topside ionosphere in the postmidnight hours. The He+ layering phenomenon has been observed during both solar maximum and solar minimum conditions. During solar maximum the layer is well defined, giving maximum relative abundances of over 50%. The observational results also show regions of He+ dominance in the topside ionosphere during solar maximum in the height range 750–1200 km. During solar minimum the magnitude of the layer is less, giving a maximum relative abundance of only ?20%; however, the layer is still a well-defined feature. The coupled thermosphere-ionosphere-plasmasphere (CTIP) model is shown to model accurately the He+ layer and the regions of He+ dominance, provided that the modeled temperature profiles are normalized to the observed values. This study serves to further highlight the importance of helium ions in the topside ionosphere, particularly during solar maximum nighttime conditions.
BibTeX:
@article{Wilford2003,
  author = {Wilford, C. R. and Moffett, R. J. and Rees, J. M. and Bailey, G. J. and Gonzalez, S. A.},
  title = {Comparison of the He+ layer observed over Arecibo during solar maximum and solar minimum with CTIP model results},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2003},
  volume = {108},
  number = {A12},
  pages = {n/a-n/a},
  url = {http://dx.doi.org/10.1029/2003JA009940},
  doi = {10.1029/2003JA009940}
}
Bishop R, Earle G, Gonzalez S, Sulzer M and Collins S (2002), "Inferred vertical ion velocities associated with intermediate layers ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 64(12-14), pp. 1471-1477.
BibTeX:
@article{Bishop2002,
  author = {R.L Bishop and G.D Earle and S.A Gonzalez and M.P Sulzer and S.C Collins},
  title = {Inferred vertical ion velocities associated with intermediate layers },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2002},
  volume = {64},
  number = {12-14},
  pages = {1471-1477},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682602001116},
  doi = {10.1016/S1364-6826(02)00111-6}
}
Collins SC, Plane JM, Kelley MC, Wright TG, SoldÀn P, Kane TJ, Gerrard AJ, Grime BW, Rollason RJ, Friedman JS, Gonzalez SA, Zhou Q, Sulzer MP and Tepley CA (2002), "A study of the role of ion–molecule chemistry in the formation of sporadic sodium layers", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 64(7), pp. 845 - 860.
Abstract: Over two campaigns in 1998 and 1999, multiple sporadic sodium events were observed by the Arecibo Observatory sodium density lidar while simultaneously monitoring the plasma density using the incoherent scatter radar. In this paper, we test the theoretical explanation proposed by Cox and Plane (1998) where Na+ in a plasma layer is neutralized via an ion–molecule mechanism to form a sporadic sodium layer. A particular challenge is to interpret observations made in a Eulerian frame of observation where the spatial and temporal characteristics of events cannot easily be separated. The reaction scheme in the original mechanism is modified to include the reactions NaO++N2--Na+•N2+O and NaO++O2--Na++O3, following the results of theoretical quantum calculations. Six unique case studies of sporadic sodium layers are presented here, and excellent agreement between simulation and observations was obtained for five of them.
BibTeX:
@article{Collins2002a,
  author = {Stephen C. Collins and John M.C. Plane and Michael C. Kelley and Timothy G. Wright and Pavel SoldÀn and Timothy J. Kane and Andrew J. Gerrard and Brent W. Grime and Rosie J. Rollason and Jonathan S. Friedman and Sixto A. Gonzalez and Qihou Zhou and Michael P. Sulzer and Craig A. Tepley},
  title = {A study of the role of ion–molecule chemistry in the formation of sporadic sodium layers},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2002},
  volume = {64},
  number = {7},
  pages = {845 - 860},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682602001293},
  doi = {10.1016/S1364-6826(02)00129-3}
}
Friedman JS, Collins SC, Delgado R and Castleberg PA (2002), "Mesospheric potassium layer over the Arecibo Observatory, 18.3°N 66.75°W", Geophysical Research Letters. Vol. 29(5), pp. 15-1-15-4.
Abstract: A resonance lidar has made regular measurements of mesospheric potassium at the Arecibo Observatory (18.3°N, 66.75°W) since July 1999. Through July 2001 a total of 65 nights of density measurements were carried out, amounting to several nights each month over most of the period. The layer shows considerable nightly and seasonal variation: Spring and early summer nights had frequent sporadic layer activity; nightly variability in the layer width was large due to sporadic layer activity, but the seasonal variation was small; the altitude of the layer centroid was fairly constant throughout the year; and the column abundance showed semi-annual variation. These results are compared with a similar set of potassium measurements from a mid-latitude site, and the latitudinal implications are discussed.
BibTeX:
@article{Friedman2002,
  author = {Friedman, Jonathan S. and Collins, Stephen C. and Delgado, RubÈn and Castleberg, Paul A.},
  title = {Mesospheric potassium layer over the Arecibo Observatory, 18.3°N 66.75°W},
  journal = {Geophysical Research Letters},
  year = {2002},
  volume = {29},
  number = {5},
  pages = {15-1-15-4},
  url = {http://dx.doi.org/10.1029/2001GL013542},
  doi = {10.1029/2001GL013542}
}
Kamalabadi F, Bust G, Dymond K, Gonzalez S, Bernhardt P, Chakrabarti S, Cotton D, Stephan A, McCoy R, Budzien S and Thonnard S (2002), "Tomographic studies of aeronomic phenomena using radio and UV techniques", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 64(12-14), pp. 1573-1580.
Abstract: Tomographic characterization of ionospheric and thermospheric structures using integrated line-of-sight measurements provides a unifying paradigm for the investigation of various aeronomic phenomena. In radio tomography, measurements of the total electron content (TEC) obtained using a chain of ground receivers and a transit satellite are inverted to reconstruct a two-dimensional electron density profile. Similarly, prominent optically thin UV emissions, such as 911 and produced by radiative recombination of O+, provide the means to obtain F-region electron densities from space-based spectroscopic measurements. The existence of a number of UV sensors in orbit and in planning stage provide the means to carry out such tomographic remote sensing investigations on global scales. The inherent non-ideal acquisition geometry of such remote sensing observations, however, results in limited-angle tomographic inverse problems that are both ill-posed and ill-conditioned. Furthermore, the intrinsic presence of noise, especially in the case of UV measurements, imposes challenges on conventional reconstruction methods. To overcome these limitations, we approach the solution of these inverse problems from a regularization standpoint. In particular, we apply regularization by incorporating appropriate edge-preserving regularizing functionals that enforce piecewise smoothness of the solution. This paper describes these techniques, investigates associated inversion issues, and demonstrates their applicability through a case study.
BibTeX:
@article{Kamalabadi2002,
  author = {Kamalabadi, Farzad and Bust, G. and Dymond, K. and Gonzalez, S. and Bernhardt, P. and Chakrabarti, S. and Cotton, D. and Stephan, A. and McCoy, R. and Budzien, S. and Thonnard, S.},
  title = {Tomographic studies of aeronomic phenomena using radio and UV techniques},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2002},
  volume = {64},
  number = {12-14},
  pages = {1573-1580},
  url = {http://dx.doi.org/10.1016/s1364-6826(02)00096-2},
  doi = {10.1016/s1364-6826(02)00096-2}
}
Kelley M, Makela J and Saito A (2002), "The mid-latitude F region at the mesoscale: some progress at last", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 64(12–14), pp. 1525 - 1529.
Abstract: Almost no new theoretical work has been conducted in the area of mid-latitude F-region plasma instabilities since Perkin's (J. Geophys. Res. 78 (1973) 218) linear theory. New experimental data now suggest that the nonlinear development of mid-latitude F-region structures includes large polarization electric fields which dominate the final state. Airglow and radar data show that SumP is greatly depleted in some regions, which is in agreement with a polarization hypothesis. We hope these new results will inspire new simulations with some anticipation of solving this perplexing but fascinating problem.
BibTeX:
@article{Kelley2002,
  author = {M.C Kelley and J.J Makela and A Saito},
  title = {The mid-latitude F region at the mesoscale: some progress at last},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2002},
  volume = {64},
  number = {12–14},
  pages = {1525 - 1529},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682602000901},
  doi = {10.1016/S1364-6826(02)00090-1}
}
Meisel DD, Janches D and Mathews JD (2002), "Extrasolar Micrometeors Radiating from the Vicinity of the Local Interstellar Bubble", The Astrophysical Journal. Vol. 567, pp. 323-341.
Abstract: Over 12,000 micrometeor detections obtained mainly during 1997 November 15-20 and over a similar period in 1998 with the Arecibo UHF (430 MHz) radar have been processed so far. Out of this particular sample, nearly 3000 particles show measurable decelerations from which particle sizes can be estimated and extra-atmospheric velocities obtained by direct numerical integration through an appropriate MSIS model atmosphere. From this subsample, 143 objects that either had distinct 1 AU heliocentric hyperbolic orbits or were on elliptical orbits of high eccentricity with semimajor axes greater than 5 AU were found to have originally hyperbolic orbits at distances between 50 and 100 AU. Original extrasolar orbits, velocities, and radiants have been calculated by a Cowell-method, numerical integration back 10 yr into the past, when these particles first encountered the solar system at greater than 50 AU. The perturbation calculations included solar radiation pressure, solar wind magnetic field deflections, and the gravitational influence of Jupiter, Saturn, Uranus, and Neptune. The original extrasolar particle sample was parsed down in several ways to make a final list of interstellar particle (ISP) candidates. In Galactic coordinates relative to an assumed LSR (&alpha; = 18 h , &#240; = 30 &deg;, v = 20 km &deg;s -1 ), most of the remaining 108 ISP radiants form an extended cluster that appears to be coming from the region of the Local Bubble or the Local Cavity. In a new LSR determined by the mean ISP velocities, many of the particles appear to radiate from a region stretching from the Vela supernova to the vicinity of the Geminga pulsar. The Geminga supernova is a more likely source or transport agent of the Arecibo ISPs because of its greater age and relatively small distance from the Sun. The likelihood of a nearby supernova as an ISP source or at least an ISP transport mechanism is discussed is some detail. It is suggested that the Arecibo ISPs are samples at 1 AU of the particles detected earlier by the Pioneer 10 and 11 spacecraft between 5 and 18 AU.
BibTeX:
@article{Meisel2002,
  author = {David D. Meisel and Diego Janches and John. D. Mathews},
  title = {Extrasolar Micrometeors Radiating from the Vicinity of the Local Interstellar Bubble},
  journal = {The Astrophysical Journal},
  year = {2002},
  volume = {567},
  pages = {323-341},
  doi = {10.1086/322317}
}
Meisel DD, Janches D and Mathews JD (2002), "The Size Distribution of the Arecibo Interstellar Particles and Its Implications", The Astrophysical Journal. Vol. 579, pp. 895-904.
Abstract: Size histograms of all Arecibo ultra-high-frequency radar micrometeors detected in 1997-1998 whose radii were measured by atmospheric drag are presented. Most can be fitted with either a lognormal function or, alternatively, one or more power-law functions. Either form is indicative of significant fragmentation. The interplanetary dust particle (IDP) histogram results are discussed and compared with those considered to be extrasolar particles, including a subset of those deemed to be true interstellar particles (ISPs). The Arecibo IDP power-law results are shown to agree well with those derived from IRAS dust bands and Long-Duration Exposure Facility cratering, thus confirming the applicability of the sample to the derivation of mass estimates. A dichotomy between size histograms of particles with preperihelion Earth encounters and those with postperihelion encounters is evidence that significant size histogram change occurs when the smallest particles, including all ISPs, pass close to the Sun, even if only once. A small sample of previously undetected Arecibo postperihelion ISPs coming from the direction of the known Ulysses gas and dust flow are shown to have a size distribution and solar system dynamical properties similar to other Arecibo ISPs and therefore can be combined with previous ISP results to obtain a more robust sample. Derived mass flux points for the Arecibo ISPs agree well (over 5 orders of magnitude of mass) with a previously derived mass flux distribution function for Ulysses/Galileo spacecraft dust. This combined spacecraft and ground-based mass flux function is then used to infer a number of interesting mass-related solar system and astrophysical quantities.
BibTeX:
@article{Meisel2002a,
  author = {David D. Meisel and Diego Janches and John. D. Mathews},
  title = {The Size Distribution of the Arecibo Interstellar Particles and Its Implications},
  journal = {The Astrophysical Journal},
  year = {2002},
  volume = {579},
  pages = {895-904},
  doi = {10.1086/342919}
}
Pasko VP, Stanley M, Mathews JD, Inan US and Wood T (2002), "Electrical discharge from a thundercloud top to the lower ionosphere", Nature. Vol. 416, pp. 152-154.
Abstract: For over a century, numerous undocumented reports have appeared about unusual large-scale luminous phenomena above thunderclouds and, more than 80 years ago, it was suggested that an electrical discharge could bridge the gap between a thundercloud and the upper atmosphere. Since then, two classes of vertically extensive optical flashes above thunderclouds have been identified—sprites and blue jet. Sprites initiate near the base of the ionosphere, develop very rapidly downwards at speeds which can exceed 107 m s-1 , and assume many different geometrical forms. In contrast, blue jets develop upwards from cloud tops at speeds of the order of 105 m s-1 and are characterized by a blue conical shape. But no experimental data related to sprites or blue jets have been reported which conclusively indicate that they establish a direct path of electrical contact between a thundercloud and the lower ionosphere. Here we report a video recording of a blue jet propagating upwards from a thundercloud to an altitude of about 70 km, taken at the Arecibo Observatory, Puerto Rico. Above an altitude of 42 km—normally the upper limit for blue jets and the lower terminal altitude for sprites—the flash exhibited some features normally observed in sprites. As we observed this phenomenon above a relatively small thunderstorm cell, we speculate that it may be common and therefore represent an unaccounted for component of the global electric circuit.
BibTeX:
@article{Pasko2002,
  author = {Pasko, V. P. and Stanley, M. and Mathews, J. D and Umran S. Inan and Wood, T.},
  title = {Electrical discharge from a thundercloud top to the lower ionosphere},
  journal = {Nature},
  year = {2002},
  volume = {416},
  pages = {152-154},
  url = {http://www.nature.com/nature/journal/v416/n6877/full/416152a.html},
  doi = {10.1038/416152a}
}
Raizada S and Tepley CA (2002), "Iron Boltzmann lidar temperature and density observations from Arecibo - An initial comparison with other techniques", Geophysical Research Letters. Vol. 29(12), pp. 1-1/1-4.
Abstract: We introduce the first measurements of upper atmospheric temperature made from the Arecibo Observatory using the iron Boltzmann lidar technique. We use a single laser transmitter that can flip between two emissions every other pulse, which is suitable to observe the two iron transitions within the same region of space. Comparisons are made with airglow measurements and the MSIS-90 model to estimate temperature, and with incoherent scatter radar observations to associate the structure of electron concentration with enhancements observed in the concentration of neutral iron. We find good agreement between lidar and airglow derived temperatures near the mesopause, while the model tends to underestimate the thermal depth of the mesopause at Arecibo compared with observations. In addition, simultaneous temperatures measured via lidar and airglow may help to clarify the heights where the airglow emissions occur.
BibTeX:
@article{Raizada2002,
  author = {Raizada, Shikha and Tepley, Craig A.},
  title = {Iron Boltzmann lidar temperature and density observations from Arecibo - An initial comparison with other techniques},
  journal = {Geophysical Research Letters},
  year = {2002},
  volume = {29},
  number = {12},
  pages = {1-1/1-4},
  url = {http://dx.doi.org/10.1029/2001GL014535},
  doi = {10.1029/2001GL014535}
}
Sethi NK and Mahajan KK (2002), "The bottomside parameters B0,B1 obtained from incoherent scatter measurements during a solar maximum and their comparisons with the IRI-2001 model", Annales Geophysicae. Vol. 20, pp. 817-822.
BibTeX:
@article{Sethi2002,
  author = {Sethi, N K and Mahajan, K K},
  title = {The bottomside parameters B0,B1 obtained from incoherent scatter measurements during a solar maximum and their comparisons with the IRI-2001 model},
  journal = {Annales Geophysicae},
  year = {2002},
  volume = {20},
  pages = {817-822},
  doi = {10.5194/angeo-20-817-2002}
}
Starks MJ (2002), "Effects of HF heater-produced ionospheric depletions on the ducting of VLF transmissions: A ray tracing study", Journal of Geophysical Research: Space Physics. Vol. 107(A11), pp. SIA 3-1/SIA 3-9.
BibTeX:
@article{Starks2002,
  author = {Starks, M. J.},
  title = {Effects of HF heater-produced ionospheric depletions on the ducting of VLF transmissions: A ray tracing study},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2002},
  volume = {107},
  number = {A11},
  pages = {SIA 3-1/SIA 3-9},
  doi = {10.1029/2001JA009197}
}
Swartz WE, Collins SC, Kelley MC, Makela JJ, Kudeki E, Franke S, Urbina J, Aponte N, Gonzalez S, Sulzer MP and Friedman JS (2002), "First observations of an F-region turbulent upwelling coincident with severe E-region plasma and neutral atmosphere perturbations", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 64, pp. 1545-1556.
BibTeX:
@article{Swartz2002,
  author = {Swartz, W. E. and Collins, S. C. and Kelley, M. C. and Makela, J. J. and Kudeki, E. and Franke, S. and Urbina, J. and Aponte, N. and Gonzalez, S. and Sulzer, M. P. and Friedman, J. S.},
  title = {First observations of an F-region turbulent upwelling coincident with severe E-region plasma and neutral atmosphere perturbations},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {2002},
  volume = {64},
  pages = {1545-1556},
  doi = {10.1016/S1364-6826(02)00092-5}
}
Aponte N, Sulzer MP and Gonzalez SA (2001), "Corection of the Jicamarca electron-ion temperature ratio problem: Verifying the effect of electron Coulomb collisions on the incoherent scatter spectrum", Journal of Geophysical Research: Space Physics. Vol. 106(A11), pp. 24785-24793.
Abstract: Ever since the first attempts to fit Jicamarca autocorrelation function (ACF) measurements in the 1970s using a full nonlinear least squares analysis, an apparent electron-ion temperature ratio below unity has been deduced for a large portion of the F region data. The cause of this unexpected and geophysically unreasonable result has been a mystery until recently, when Sulzer and Gonzalez [1999] (herein SG) explained how electron Coulomb collisions can distort, or narrow, the incoherent backscatter spectrum, and that for this narrowing to be observable two conditions must be met. First, the radar k vector must lie in a small range near perpendicular to the magnetic field, and second, the radar wavelength must be sufficiently long. Both of these conditions are true at Jicamarca. The accurate calculations from the SG theory are now available in a compact library, which we have incorporated into an incoherent scatter least squares fitting code. Using this code, we have reduced Jicamarca ACF data taken with the Faraday double-pulse mode, and find that the SG theory correctly interprets the ACF data from Jicamarca, thereby solving the longstanding Te/Ti ratio problem and thus allowing accurate electron and ion temperature measurements.
BibTeX:
@article{Aponte2001,
  author = {Aponte, NÈstor and Sulzer, Michael P. and Gonzalez, Sixto A.},
  title = {Corection of the Jicamarca electron-ion temperature ratio problem: Verifying the effect of electron Coulomb collisions on the incoherent scatter spectrum},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2001},
  volume = {106},
  number = {A11},
  pages = {24785-24793},
  url = {http://dx.doi.org/10.1029/2001JA000103},
  doi = {10.1029/2001JA000103}
}
Gorgolewski S and Rozej B (2001), "Evidence for electrotropism in some plant species", Advances in Space Research . Vol. 28(4), pp. 633-638.
BibTeX:
@article{Gorgolewski2001,
  author = {S Gorgolewski and B Rozej},
  title = {Evidence for electrotropism in some plant species},
  journal = {Advances in Space Research },
  year = {2001},
  volume = {28},
  number = {4},
  pages = {633-638},
  doi = {10.1016/S0273-1177(01)00371-4}
}
Hickey MP (2001), "Reflection of a long-period gravity wave observed in the nightglow over Arecibo on May 8–9, 1989?", Journal of Geophysical Research: Atmospheres. Vol. 106(D22), pp. 28199-28208.
Abstract: During the Arecibo Initiative for Dynamics of the Atmosphere (AIDA) campaign in 1989 a characteristic of gravity wave perturbations observed in mesopause region airglow emissions was that airglow brightness fluctuations and airglow-derived temperature fluctuations often occurred either in phase or in antiphase. This stimulated the development of a theory suggesting that such in-phase fluctuations were most probably the result of strong reflections occurring in the mesosphere and lower thermosphere region. Recent examination of a particular wave event and application of simple WKB-type theory has appeared to support this hypothesis. Here we use a full-wave model and a WKB-type model, each coupled with a chemical-airglow fluctuation model describing O2 atmospheric and OH Meinel airglow fluctuations, to assess the strength of wave reflection and also to explicitly calculate the phase difference between the airglow brightness and the temperature fluctuations. Our results suggest that reflection is not strong for the particular wave event, and the model produces fairly large phase differences between the airglow brightness and the temperature fluctuations (?35° and ?134°–165° for the O2 atmospheric and OH airglow emissions, respectively). These results are not particularly sensitive to the nominal mean winds used in the simulations. There is an instance when a region of minimum refractive index occurs directly above a region in which reflection is strongest, suggesting that the two are related. However, the reflection does not appear to be strong. Our results suggest that chemical effects can account for the inferred phases of the observed airglow fluctuations and that effects associated with wave reflection appear to play a relatively minor role in the airglow fluctuations.
BibTeX:
@article{Hickey2001,
  author = {Hickey, Michael P.},
  title = {Reflection of a long-period gravity wave observed in the nightglow over Arecibo on May 8–9, 1989?},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2001},
  volume = {106},
  number = {D22},
  pages = {28199-28208},
  url = {http://dx.doi.org/10.1029/2001JD900221},
  doi = {10.1029/2001JD900221}
}
Janches D, Meisel DD and Mathews JD (2001), "Orbital Properties of the Arecibo Micrometeoroids at Earth Interception", Icarus. Vol. 150, pp. 206-218. Elsevier Science.
Abstract: Using the Arecibo Observatory (AO) 430-MHz Radar we have developed a Doppler technique to measure very precise micrometeor instantaneous velocities directly from the meteor head echo. In addition, a large number of the observed meteoroids show deceleration. With the velocity, the deceleration, and the assumptions of a spherical shape and a mean micrometeoroid mass density, we have obtained estimates of in-atmosphere particle sizes. The size estimate, the MSIS model atmosphere, and the measured deceleration are used to obtain the meteor extra-atmospheric speeds, assuming these particles undergo little mass-loss prior to and during the time we detect them (Janches et al. 2000b, Icarus145, 53–63). Orbital elements at 1 AU are presented and discussed. These results have not been corrected for perturbation effects such as radiation pressure, Poynting–Robertson drag, attraction by the giant planets, and photoelectric charging effects. So far, over 7700 detections obtained during November 1997 and 3500 during the November 1998 observation campaigns have been analyzed. The observing periods included the Leonids meteor shower, but none of the orbits are recently derived from it. Out of these detections, we present details of over 1500 orbits with eccentricities less than unity. These orbits show (a) a depletion of postperihelion particles with small perihelion distance, suggesting the possibility of collisional and thermal destruction, and (b) an enhancement of particles with perihelia in the zone between Mercury and Venus. Also discussed are 40 betha-meteoroids (with radii less than 0.5 um) dynamically related to the elliptical orbit population with q<0.7 AU. We interpret the latter results on the basis of Poynting–Robertson drag and the electromagnetic resonant effects proposed by G. E. Morfill and E. Grun (1979, Planet. Space Sci.27, 1269–1282). Comparison with previous data sets indicates that most of the AO micrometeoroid orbits are well randomized and that association with a particular parent body is unlikely.
BibTeX:
@article{Janches2001,
  author = {Janches, D and Meisel, D D and Mathews, J D},
  title = {Orbital Properties of the Arecibo Micrometeoroids at Earth Interception},
  journal = {Icarus},
  publisher = {Elsevier Science},
  year = {2001},
  volume = {150},
  pages = {206-218},
  url = {http://dx.doi.org/10.1006/icar.2000.6575},
  doi = {10.1006/icar.2000.6575}
}
Kane T, Grime B, Franke S, Kudeki E, Urbina J, Kelley M and Collins S (2001), "Joint observations of sodium enhancements and field-aligned ionospheric irregularities", Geophysical Research Letters. Vol. 28(7), pp. 1375-1378.
Abstract: Resonance Lidar observations of neutral sodium and VHF coherent scatter radar observations of field-aligned 3-meter irregularities were obtained during the Coqui II rocket campaign in Puerto Rico. The Lidar, a facility instrument at the Arecibo Observatory (18.3°N, 66.8°W), and the University of Illinois Radar, located near Salinas on the south of the island, both monitored volumes near where the uplegs of the nominal rocket trajectories intersected the E-region. The Observatory's Incoherent Scatter Radar was also used to characterize the plasma layers. Preliminary investigation of the data sets has shown a potential correspondence between VHF backscatter from plasma layers and a new class of characteristic enhancements in the neutral sodium.
BibTeX:
@article{Kane2001,
  author = {Kane, T. and Grime, B. and Franke, S. and Kudeki, E. and Urbina, J. and Kelley, M. and Collins, S.},
  title = {Joint observations of sodium enhancements and field-aligned ionospheric irregularities},
  journal = {Geophysical Research Letters},
  year = {2001},
  volume = {28},
  number = {7},
  pages = {1375-1378},
  url = {http://dx.doi.org/10.1029/2000GL012176},
  doi = {10.1029/2000GL012176}
}
Kerr RB, Garcia R, He X, Noto J, Lancaster RS, Tepley CA, Gonzalez SA, Friedman J, Doe RA, Lappen M and McCormack B (2001), "Secular variability of the geocoronal Balmer-alpha brightness: magnetic activity and possible human influences", Journal of Geophysical Research: Space Physics. Vol. 106(A12), pp. 28819-28830.
Abstract: Measurements of the geocoronal Balmer-alpha (H&alpha;) brightness taken between 1983 and 1994 at the Arecibo Observatory (18.35° N, 66.75° W) occasionally display aperiodic brightness variations that we attribute to a local response of exospheric hydrogen abundance to geomagnetic activity. Approximately twofold H&alpha; brightness enhancements in the days following moderate storm onset conditions are demonstrated, and the absolute brightness during these events is significantly greater than modeled brightness based on quiet geomagnetic conditions. Although there are no direct measurements of the line center solar Lyman beta (Ly &beta;) flux that pumps H&alpha; during these events, the magnitude of the brightness enhancements and the temporal reproducibility of the phenomena (following onset of all storms in our data) make it likely that the enhanced H&alpha; brightness is due to enhanced column abundances of hydrogen in the exosphere above Arecibo and not to sporadic increases in the solar Ly &beta; flux. Increased hydrogen abundance due to thermal expansion of the midlatitude atmosphere following propagation of the auroral heating event cannot account for the entire enhancement. The data also suggest that H&alpha;. brightness has become systematically stronger from 1984 to 1994, independent of solar cycle variability or variations due to geomagnetic activity. An increase of ~3% per year, may be attributable to real change in the geocoronal hydrogen column abundance during the period, and is possibly a consequence of increasing hydrogenous species concentrations in the lower atmosphere. The enhancement of geocoronal H&alpha; brightness between 1984 and 1994 may be the consequence of increasing methane in the troposphere and may signal that the effects of methane deposition in the lower atmosphere have propagated throughout the atmosphere.
BibTeX:
@article{Kerr2001,
  author = {Kerr, R. B. and Garcia, R. and He, X. and Noto, J. and Lancaster, R. S. and Tepley, C. A. and Gonzalez, S. A. and Friedman, J. and Doe, R. A. and Lappen, M. and McCormack, B.},
  title = {Secular variability of the geocoronal Balmer-alpha brightness: magnetic activity and possible human influences},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2001},
  volume = {106},
  number = {A12},
  pages = {28819-28830},
  url = {http://dx.doi.org/10.1029/1999JA900187},
  doi = {10.1029/1999JA900187}
}
Kerr RB, Garcia R, He X, Noto J, Lancaster RS, Tepley CA, Gonzalez SA, Friedman J, Doe RA, Lappen M and McCormack B (2001), "Periodic variations of geocoronal Balmer-alpha brightness due to solar-driven exospheric abundance variations", Journal of Geophysical Research: Space Physics. Vol. 106(A12), pp. 28797-28817.
Abstract: Measurements of the geocoronal Balmer-alpha (H&alpha;) brightness have been made at the Arecibo Observatory during 11 separate periods since 1983 using both a Fabry-Perot interferometer and a tilting filter photometer. The tilting filter photometer is calibrated for absolute sensitivity using a constant brightness source traceable to National Institute of Standards and Techniques (NIST) standards and is used to cross-calibrate the Fabry-Perot interferometer. Since the observational technique has not changed since 1983, and since the data analyses technique are uniform, these data provide a measure of the solar cycle variation of H&alpha; brightness at Arecibo. Unlike earlier studies, we discern no systematic discrepancy between the H&alpha; brightness and estimates of the solar Lyman-beta flux that pumps the resonant fluorescent H&alpha; emission. Rather, we conclude that geocoronal hydrogen abundance is generally (but not always) larger than models suggest, although not systematically so. The largest H&alpha; emission is measured during solar minimum conditions, when brightness is approximately 50% greater than during solar maximum conditions, for measurements at solar depression angles from 15° to 35°. Above about 40° solar depression (corresponding to an illuminated column with a base at approximately 2000 km), no solar cycle variation is evident, and the brightness there is persistently greater than models. Intricacies of the Lyman-beta radiative transport problem make detection of an early morning maximum of hydrogen density near the exobase difficult using brightness data alone, although the H&alpha; brightness is generally asymmetric with respect to local midnight, with brighter emission in the postmidnight sector. Studies of the semidiurnal (nighttime) variation demonstrate that the H&alpha; brightness can vary by a factor of 2 over a period of days.
BibTeX:
@article{Kerr2001a,
  author = {Kerr, R. B. and Garcia, R. and He, X. and Noto, J. and Lancaster, R. S. and Tepley, C. A. and Gonzalez, S. A. and Friedman, J. and Doe, R. A. and Lappen, M. and McCormack, B.},
  title = {Periodic variations of geocoronal Balmer-alpha brightness due to solar-driven exospheric abundance variations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2001},
  volume = {106},
  number = {A12},
  pages = {28797-28817},
  url = {http://dx.doi.org/10.1029/1999JA900186},
  doi = {10.1029/1999JA900186}
}
Leyser T (2001), "Stimulated electromagnetic emissions by high-frequency electromagnetic pumping of the ionospheric plasma", Space Science Reviews. Vol. 98(3-4), pp. 223-328.
BibTeX:
@article{Leyser2001,
  author = {Leyser, T.B.},
  title = {Stimulated electromagnetic emissions by high-frequency electromagnetic pumping of the ionospheric plasma},
  journal = {Space Science Reviews},
  year = {2001},
  volume = {98},
  number = {3-4},
  pages = {223-328},
  doi = {10.1023/A:1013875603938}
}
Machuga D and Mathews J (2001), "Numerical simulations of three-dimensional E-region ion trajectories in realistic tidal wind and E-field structures: layer formation and transport", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 63(14), pp. 1519-1528.
BibTeX:
@article{Machuga2001,
  author = {D.W. Machuga and J.D. Mathews},
  title = {Numerical simulations of three-dimensional E-region ion trajectories in realistic tidal wind and E-field structures: layer formation and transport},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2001},
  volume = {63},
  number = {14},
  pages = {1519-1528},
  doi = {10.1016/S1364-6826(01)00033-5}
}
Mahajan KK and Sethi N (2001), "Empirical models of parameters B0, B1 from Arecibo radar measurements", Advances in Space Research. Vol. 27, pp. 17-20.
BibTeX:
@article{Mahajan2001,
  author = {Mahajan, K K and Sethi, N},
  title = {Empirical models of parameters B0, B1 from Arecibo radar measurements},
  journal = {Advances in Space Research},
  year = {2001},
  volume = {27},
  pages = {17-20},
  doi = {10.1016/S0273-1177(00)00135-6}
}
Makela JJ, Kelley MC, Gonzalez SA, Aponte N and McCoy RP (2001), "Ionospheric topography maps using multiple-wavelength all-sky images", Journal of Geophysical Research: Space Physics. Vol. 106(A12), pp. 29161-29174.
Abstract: We outline a technique to create three-dimensional topographic maps of the Earth's ionosphere. Using all-sky images at 630.0 and 777.4 nm taken with the Cornell All-Sky Imager (CASI) while located at the Arecibo Observatory, we can estimate the maximum density (Nm) and the height (Hm) of the F layer over a 1000 â 1000 km area. This is possible because to first order, the 777.4 nm emission, produced by radiative recombination, is proportional to the integral of the square of the plasma density, whereas the 630.0 nm line, produced by charge exchange and dissociative recombination, depends on both plasma height and density. Using the neutral atmosphere given by the Mass Spectrometer Incoherent Scatter (MSIS-86) model and electron densities from the international reference ionosphere 1995 (IRI-95) model, we show that the estimates given by these maps are good to within 5% of the values used as input into the models. These errors are slightly larger (10%) when extreme gradients in the height of the F layer are present. We apply our technique to two different nights in 1999. In one example these maps show a steeply rising ridge of ionization stretching equatorward of the Caribbean site, punctuated by a series of parallel ridges and valleys. We compare these observations with previous work at Arecibo during very high magnetic activity. In our case we find no evidence for particle precipitation and agree with Sahai et al. [1981a] that spatial variations may have affected the earlier study. Another example shows the Appleton anomaly much farther north than normal. Instability processes are indicated in the former case, while physical mechanisms associated with a magnetic storm are explored in the latter case.
BibTeX:
@article{Makela2001,
  author = {Makela, Jonathan J. and Kelley, Michael C. and Gonzalez, Sixto A. and Aponte, Nestor and McCoy, Robert P.},
  title = {Ionospheric topography maps using multiple-wavelength all-sky images},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2001},
  volume = {106},
  number = {A12},
  pages = {29161-29174},
  url = {http://dx.doi.org/10.1029/2000JA000449},
  doi = {10.1029/2000JA000449}
}
Makela JJ, Kelley MC, Sojka JJ, Pi X and Mannucci AJ (2001), "GPS normalization and preliminary modeling results of total electron content during a midlatitude space weather event", Radio Science. Vol. 36(2), pp. 351-361.
Abstract: On November 22–23, 1997, a geomagnetic storm occurred during a period of excellent viewing conditions over the Arecibo Observatory in Puerto Rico. Here we explore the total electron content (TEC) registered by Global Positioning System (GPS) receivers located close to the Cornell All-Sky Imager (CASI) at the Arecibo Observatory. The storm began with the equatorward surge of a very high (100% increase) TEC enhancement stretching for many hours of local time on the dayside. At dusk the TEC over the Caribbean remained elevated with levels equal to the noontime monthly averages. During the event the TEC was highly structured and clearly correlated with high and low airglow emission levels. In one fortuitous instance a common ionospheric penetration point (15 km apart), shared by two GPS satellites viewed from two receiving stations, registered an 8 TEC unit difference during the active period. We show that a GPS station can be calibrated using the pseudorange method and a reliable data-driven technique during quiet conditions and still have absolute TEC capability within 2 TEC units (RMS) 5 days later. We compare the observations to a climatological model which, although reasonable for quiet times, is very poor during the storm period. We also present an independent evaluation of the GPS TEC. This study is an initial step toward quality control of this database, needed before it is used in an assimilation model.
Review: On November 22–23, 1997, a geomagnetic storm occurred during a period of excellent viewing conditions over the Arecibo Observatory in Puerto Rico. Here we explore the total electron content (TEC) registered by Global Positioning System (GPS) receivers located close to the Cornell All-Sky Imager (CASI) at the Arecibo Observatory. The storm began with the equatorward surge of a very high (100% increase) TEC enhancement stretching for many hours of local time on the dayside. At dusk the TEC over the Caribbean remained elevated with levels equal to the noontime monthly averages. During the event the TEC was highly structured and clearly correlated with high and low airglow emission levels. In one fortuitous instance a common ionospheric penetration point (15 km apart), shared by two GPS satellites viewed from two receiving stations, registered an 8 TEC unit difference during the active period. We show that a GPS station can be calibrated using the pseudorange method and a reliable data-driven technique during quiet conditions and still have absolute TEC capability within 2 TEC units (RMS) 5 days later. We compare the observations to a climatological model which, although reasonable for quiet times, is very poor during the storm period. We also present an independent evaluation of the GPS TEC. This study is an initial step toward quality control of this database, needed before it is used in an assimilation model.
BibTeX:
@article{Makela2001a,
  author = {Makela, Jonathan J. and Kelley, Michael C. and Sojka, Jan J. and Pi, Xiaoqing and Mannucci, Anthony J.},
  title = {GPS normalization and preliminary modeling results of total electron content during a midlatitude space weather event},
  journal = {Radio Science},
  year = {2001},
  volume = {36},
  number = {2},
  pages = {351-361},
  url = {http://dx.doi.org/10.1029/1999RS002427},
  doi = {10.1029/1999RS002427}
}
Mathews JD, Janches D, Meisel DD and Zhou QH (2001), "The micrometeoroid mass flux into the upper atmosphere: Arecibo results and a comparison with prior estimates", Geophysical Research Letters. Vol. 28(10), pp. 1929-1932.
Abstract: Radar micrometeor observations at Arecibo Observatory have enabled direct estimates of the meteoroid mass flux into the upper atmosphere. We report mass flux determinations from November 1997/1998 observations that are based on the observed number of meteor events per day in the 300 m diameter Arecibo beam and on particle mass determinations from that fraction of all particles for which deceleration is measured. The average mass of the Arecibo micrometeoroids that manifest observable deceleration is ~0.32/0.76 µgm/particle with a resultant annual whole Earth mass flux of 1.6 â 106/2.7 â 106 kg/yr over the ~10-5-10² µgm mass range for 1997/1998, respectively. The annual whole earth mass flux per decade of particle mass is calculated and compared with that of Ceplecha et al. [1998] (3.7 â 106 kg/yr) and with that derived by Love and Brownlee [1993] (LB) from small particle impact craters on the orbital Long Duration Exposure Facility (LDEF). We also give the LDEF results as significantly modified using the Arecibo determined average particle velocity of ~50 km/sec-much larger than the effective value of 12 km/sec used by LB. This modification results in a net LDEF mass flux of 1.8â106 kg/yr 7% of the value we determined from reanalysis of the LB data using their original 12 km/sec mean impact speed. These results may provoke some debate.
BibTeX:
@article{Mathews2001,
  author = {Mathews, J. D. and Janches, D. and Meisel, D. D. and Zhou, Q -H.},
  title = {The micrometeoroid mass flux into the upper atmosphere: Arecibo results and a comparison with prior estimates},
  journal = {Geophysical Research Letters},
  year = {2001},
  volume = {28},
  number = {10},
  pages = {1929-1932},
  url = {http://dx.doi.org/10.1029/2000GL012621},
  doi = {10.1029/2000GL012621}
}
Mathews JD, Gonzalez S, Sulzer MP, Zhou Q-H, Urbina J, Kudeki E and Franke S (2001), "Kilometer-scale layered structures inside spread-F", Geophysical Research Letters. Vol. 28(22), pp. 4167-4170.
Abstract: We report the first incoherent scatter radar observations—made at Arecibo Observatory—of remarkable bottom-side (<280 km) F-region sheet-like plasma structures with horizontal/vertical-scales of ~1 km. These structures are an apparent manifestation of spread-F, appear to give rise to VHF coherent (FAI) scattering, and are clearly electrodynamic in origin involving a form of the Perkins spread-F instability process in the presence of relatively large E-fields and horizontal plasma gradients. The net instability process appears to be associated with downwelling features characteristic of the nighttime F-region. These structures—that may be self-similar on scales of ~1–100 km—indicate considerable electrodynamic activity in the mid-latitude F-region on scales that have profound space-weather implications especially regarding deep scintillations on earth-space communications links.
BibTeX:
@article{Mathews2001a,
  author = {Mathews, J. D. and Gonzalez, S. and Sulzer, M. P. and Zhou, Q.-H. and Urbina, J. and Kudeki, E. and Franke, S.},
  title = {Kilometer-scale layered structures inside spread-F},
  journal = {Geophysical Research Letters},
  year = {2001},
  volume = {28},
  number = {22},
  pages = {4167-4170},
  url = {http://dx.doi.org/10.1029/2001GL013077},
  doi = {10.1029/2001GL013077}
}
Mathews J, Machuga D and Zhou Q (2001), "Evidence for electrodynamic linkages between spread-F, ion rain, the intermediate layer, and sporadic E: results from observations and simulations", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 63(14), pp. 1529-1543.
Abstract: High resolution ISR observations of the evening and nighttime E- and F-regions at Arecibo during both “normal” low-activity periods and during an active spread-F event reveal apparent electrodynamic links between the low-lying layers, ion-rain, and the spread-F instability process. In particular, during a 22 November 1994 event, streaks of ionization—ion rain [Mathews et al., Geophys. Res. Lett. 24 (1997) 1411]—appear to descend from the highly structured F-region base onto the 100-110 Tidal Ion Layer (TIL) system. The evening intermediate tidal ion layer, if present, is almost totally disrupted while the spread-F event is characterized by deep, almost vertical folds in electron concentration. The amplitudes of these structures are 100% with fold-structures extending from the nominal F-region base to well above the nominal peak of the F-region. Apparent periods range from less than 10min for small-scale structures to about 40min for the largest-scales. We suggest that the E-region structures are a manifestation of polarization electric fields that “map” into the E-region and are well in excess of 1mV/m in contrast to low-activity period small-scale fields of order 1mV/m. These E-fields are hypothesized to be generated in the “field” of linear (low-activity) and/or non-linear (high-activity spread-F periods) Perkins-like instabilities that are individually of relatively small horizontal-scales but occur over large horizontal distances in the bottom-side of the nighttime F-region. We present numerical simulations of 3-dimensional ion trajectories in tidal wind and electric field structures similar to those implied by these observations. These simulations extend the results of Machuga and Mathews (J. Atmos. Solar-Terres. Phys., 2001, 63(14), 1519–1528, this issue.) (Paper I) and demonstrate the formation of parallel sheets of ionization that form in the tilted plane oriented transverse to the bulk flow of the F-region that sweeps ~1mV/m amplitude E-fields quasi-periodically through a fixed location in the E-region. A fixed pointing radar sees these ionization sheets as ion-rain-like features.
BibTeX:
@article{Mathews2001b,
  author = {J.D. Mathews and D.W. Machuga and Q. Zhou},
  title = {Evidence for electrodynamic linkages between spread-F, ion rain, the intermediate layer, and sporadic E: results from observations and simulations},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {2001},
  volume = {63},
  number = {14},
  pages = {1529-1543},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682601000347},
  doi = {10.1016/S1364-6826(01)00034-7}
}
MelÈndez-Alvira DJ, Picone JM, Kelley OA, Zhou Q and Sulzer MP (2001), "Bimodality in the climatological topside electron and exospheric temperature distributions at Arecibo", Radio Science. Vol. 36(2), pp. 311-324.
Abstract: We report on the local time, occurrence frequency, and solar activity variations of the measured electron temperature and the ratio of the electron to ion temperatures at 589 km, and the inferred exospheric neutral temperatures. The World Day measurements at Arecibo, Puerto Rico, were made between 1985 and 1995, spanning both solar maximum and minimum conditions during predominantly quiet geomagnetic conditions. Histograms of the electron and exospheric temperatures reveal bimodal distributions. The electron temperature bimodality is primarily due to the sharp difference between daytime and nighttime temperatures whereas the exospheric temperature bimodality is primarily due to the difference between high and low solar activity. The nighttime exosphere and the electrons at 589 km are hotter by up to 400 K during high solar activity than during low solar activity. The daytime electrons at 589 km are, however, colder after 0800 LT during high solar activity than during low solar activity. The daytime ratio of electron to ion temperatures is also lower at high solar activity but not until after 1000 LT on average. Unlike the electron temperature at 589 km, the distribution of the electron to ion temperatures is unimodal.
BibTeX:
@article{Melendez-Alvira2001,
  author = {MelÈndez-Alvira, D. J. and Picone, J. M. and Kelley, O. A. and Zhou, Q. and Sulzer, M. P.},
  title = {Bimodality in the climatological topside electron and exospheric temperature distributions at Arecibo},
  journal = {Radio Science},
  year = {2001},
  volume = {36},
  number = {2},
  pages = {311-324},
  url = {http://dx.doi.org/10.1029/2000RS002435},
  doi = {10.1029/2000RS002435}
}
Pandey V, Sethi N and Mahajan K (2001), "Equivalent slab thickness and its variability: a study with incoherent scatter measurements", Advances in Space Research . Vol. 27(1), pp. 60-64.
Abstract: In order to check its usefulness for the IRI, incoherent scatter (I.S.) radar measurements at Arecibo (18.4° N, 66.7° W), for the solar minimum period of 1974–1977 are used to study equivalent slab thickness (EST) and its variability. While systematic diurnal changes are apparent, day-to-day and hour-to-hour fluctuations can also not be overlooked. This variability is examined in relation to the simultaneously measured F-layer peak height and electron temperature. While during nighttime, EST shows dependence upon the F-layer peak height (hmF2), it shows by day a dependence on electron temperature.
BibTeX:
@article{Pandey2001,
  author = {V.K. Pandey and N.K. Sethi and K.K. Mahajan},
  title = {Equivalent slab thickness and its variability: a study with incoherent scatter measurements},
  journal = {Advances in Space Research },
  year = {2001},
  volume = {27},
  number = {1},
  pages = {60-64},
  url = {http://www.sciencedirect.com/science/article/pii/S027311770000140X},
  doi = {10.1016/S0273-1177(00)00140-X}
}
Peria WJ and Kelley MC (2001), "Convection electric field observations near the Arecibo HF heater beam", Journal of Geophysical Research: Space Physics. Vol. 106(A9), pp. 18517-18524.
Abstract: Electric fields have been observed at the westward edge of the Arecibo HF heater beam, at the F region reflection altitude, by a sounding rocket. We first show that the floating double probe used for these measurements is functioning reliably. The data are shown to be free of sheath rectification effects within the heated volume. Away from the heater beam the double probe data show primarily motional emf, consistent with Earth frame fields of less than 2 m V m-1 (typical, on average, of summer post-midnight conditions over Arecibo), while near the heater beam, significant Earth frame fields are observed. The convective drift due to these fields is consistent with the apparent drift of simultaneously measured heater-induced field-aligned irregularities. The measured convection electric field magnitude is used to estimate the strength of the current maintaining it against the background conductivity, yielding 5 mA m-1. Estimates of the current due to ponderomotive force are lower than this value, unless one invokes electrostatic waves with electric fields roughly 8 times that of the pump field. Temperature gradient currents are estimated as well and are a possible source. The observed shear in the convection electric field is used to estimate a field-aligned current density of 0.5 uA m-2. We conclude that the heater is indeed driving convection on the scale size of the heated volume but are unable to definitively determine how the corresponding electric fields are being produced.
BibTeX:
@article{Peria2001,
  author = {Peria, W. J. and Kelley, M. C.},
  title = {Convection electric field observations near the Arecibo HF heater beam},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2001},
  volume = {106},
  number = {A9},
  pages = {18517-18524},
  url = {http://dx.doi.org/10.1029/2000JA000279},
  doi = {10.1029/2000JA000279}
}
Sasi MN and Vijayan L (2001), "Turbulence characteristics in the tropical mesosphere as obtained by MST radar at Gadanki (13.5ο½ N, 79.2ο½ E)", Annales Geophysicae. Vol. 19(8), pp. 1019-1025.
Abstract: Turbulent kinetic energy dissipation rates (?) and eddy diffusion coefficients (Kz) in the tropical mesosphere over Gadanki (13.5° N, 79.2° E), estimated from Doppler widths of MST radar echoes (vertical beam), observed over a 3-year period, show a seasonal variation with a dominant summer maximum. The observed seasonal variation of ? and Kz in the mesosphere is only partially consistent with that of gravity wave activity inferred from mesospheric winds and temperatures measured by rockets for a period of 9 years at Trivandrum (8.5° N, 77° E) (which shows two equinox and one summer maxima) lying close to Gadanki. The summer maximum of mesospheric ? and Kz values appears to be related to the enhanced gravity wave activity over the low-latitude Indian subcontinent during the southwest monsoon period (June – September). Both ? and Kz in the mesosphere over Gadanki show an increase with an increase in height during all seasons. The absolute values of observed ? and Kz in the mesosphere (above ~80 km) does not show significant differences from those reported for high latitudes. Comparison of observed Kz values during the winter above Gadanki with those over Arecibo (18.5° N, 66° W) shows that they are not significantly different from each other above the ~80 km altitude.
BibTeX:
@article{Sasi2001,
  author = {Sasi, M. N. and Vijayan, L.},
  title = {Turbulence characteristics in the tropical mesosphere as obtained by MST radar at Gadanki (13.5ο½ N, 79.2ο½ E)},
  journal = {Annales Geophysicae},
  year = {2001},
  volume = {19},
  number = {8},
  pages = {1019-1025},
  url = {www.ann-geophys.net/19/1019/2001/},
  doi = {10.5194/angeo-19-1019-2001}
}
Sethi NK and Pandey VK (2001), "Comparative study of electron density from Incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum", Annales Geophysicae. Vol. 18, pp. 1630-1634.
Abstract: Arecibo (18.4 N, 66.7 W) incoherent scatter (IS) observations of electron density N(h) are compared with the International Reference Ionosphere (IRI-95) during midday (10–14 h), for summer, winter and equinox, at solar maximum (1981). The N(h) profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option) and the Gulyaeva-B0 thickness (new option). The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option), are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0.
BibTeX:
@article{Sethi2001,
  author = {Sethi, N K and Pandey, V K},
  title = {Comparative study of electron density from Incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum},
  journal = {Annales Geophysicae},
  year = {2001},
  volume = {18},
  pages = {1630-1634},
  url = {http://www.ann-geophys.net/18/1630/2000/},
  doi = {10.1007/s00585-001-1630-0}
}
Sethi N, Pandey V and Mahajan K (2001), "Comparative study of TEC with IRI model for solar minimum period at low latitude", Advances in Space Research. Vol. 27(1), pp. 45-48.
BibTeX:
@article{Sethi2001a,
  author = {N.K. Sethi and V.K. Pandey and K.K. Mahajan},
  title = {Comparative study of TEC with IRI model for solar minimum period at low latitude},
  journal = {Advances in Space Research},
  year = {2001},
  volume = {27},
  number = {1},
  pages = {45-48},
  doi = {10.1016/S0273-1177(00)00139-3}
}
Sojka JJ, Thompson DC, Schunk RW, Bullett TW and Makela JJ (2001), "Assimilation Ionosphere Model: Development and testing with Combined Ionospheric Campaign Caribbean measurements", Radio Science. Vol. 36(2), pp. 247-259.
Abstract: Assimilation Ionosphere Model (AIM) is a physics-based, global, ionospheric specification model that is currently under development. It assimilates a diverse set of real-time (or near-real-time) measurements, such as ionograms, GPS slant total electron content (TEC), and in situ plasma measurements. This study focuses on a middle latitude ionosonde assimilation capability in both local and regional forms. The models described are capable of using theƒ0F2 and hmF2 from ionograms to generate either a local or a regional distribution of the induced plasma drift. This induced drift is usually caused by the meridional neutral wind. Results from a local model (AIM1.03L) and a regional model (AIM1.03R) are presented and compared with the international reference ionosphere (IRI) climatological predictions as well as GPS slant TEC measurements. Results from year-long studies during solar maximum show that the accuracy of the AIM1.03L model is about a factor of 2 better than that of IRI. An initial month-long regional study is also presented, and the results are almost as good. A study is also carried out using observations taken during the Combined Ionospheric Campaign (CIC) held in November, 1997, in the Caribbean. The digisonde located at Ramey Solar Observatory is used to drive the AIM1.03L model, and the predicted GPS slant TECs are compared to those observed by a GPS receiver located at St. Croix. This study confirms that this first step in preparing a weather-sensitive ionospheric representation is superior to a climatological representation. This sets the stage for the development of full assimilation of GPS TEC, in situ density measurements, etc., and it is anticipated that the AIM1.03L-R ionospheric representation will provide an accurate ionospheric specification.
BibTeX:
@article{Sojka2001,
  author = {Sojka, J. J. and Thompson, D. C. and Schunk, R. W. and Bullett, T. W. and Makela, J. J.},
  title = {Assimilation Ionosphere Model: Development and testing with Combined Ionospheric Campaign Caribbean measurements},
  journal = {Radio Science},
  year = {2001},
  volume = {36},
  number = {2},
  pages = {247-259},
  url = {http://dx.doi.org/10.1029/1999RS002411},
  doi = {10.1029/1999RS002411}
}
Thonnard SE and McCoy RP (2001), "Overview of the 1998 Caribbean Ionospheric Campaign", Radio Science. Vol. 36(5), pp. 1199-1207.
Abstract: The Office of Naval Research and the Naval Research Laboratory have coordinated the first of a series of scientific campaigns to gather ionospheric measurements to characterize the dynamics of space weather. The campaign participants include several universities, government agencies, and private corporations. The focus of the campaign is to gather high-quality, spatial and temporal coincident data to study midlatitude ionospheric specification, compare various ionospheric measurement techniques, and lay the groundwork for validating new ionospheric monitoring instruments and models. The location of the campaign was chosen to further investigate midlatitude ionospheric depletions previously observed above Puerto Rico. In addition to direct comparisons an ionospheric specification model currently under construction will assimilate the data set collected during these campaigns. This paper presents an overview of the first campaign that occurred in the Caribbean, centered about Puerto Rico, in June 1998. The paper also includes a brief description of the variety of monitoring techniques used and the preliminary results of the comparison.
BibTeX:
@article{Thonnard2001,
  author = {Thonnard, S. E. and McCoy, R. P.},
  title = {Overview of the 1998 Caribbean Ionospheric Campaign},
  journal = {Radio Science},
  year = {2001},
  volume = {36},
  number = {5},
  pages = {1199-1207},
  url = {http://dx.doi.org/10.1029/2000RS002431},
  doi = {10.1029/2000RS002431}
}
Aponte N, Gonzalez SA, Kelley MC, Tepley CA, Pi X and Iijima B (2000), "Advection of the equatorial anomaly over Arecibo by small-storm related disturbance dynamo electric fields", Geophysical Research Letters. Vol. 27(18), pp. 2833-2836.
Abstract: During highly disturbed geomagnetic periods, both the Arecibo radar and the Ramey ionosonde have recorded impressive nighttime ionospheric enhancements in which the peak electron density exceeded 1 â 1012 m?3 and the F2 peak height went above 400 km. In the past it has been suggested that these events could be caused by either a downward plasmaspheric flux that increases the density in the F region or by an eastward electric field that pushes the equatorial anomaly poleward to the Caribbean sector. On February 17–18, 1999 the Arecibo radar made observations during an event in which the electron density again rose to daytime values near midnight. For this event, the peaks in density were observed predominantly southeast of Arecibo while the ions sustained a northward-eastward motion due to an eastward-southward storm dynamo electric field. TEC maps from GPS for this night confirmed that the density enhancements were due to a poleward expansion of the equatorial anomaly.
BibTeX:
@article{Aponte2000,
  author = {Aponte, NÈstor and Gonzalez, Sixto A. and Kelley, Michael C. and Tepley, Craig A. and Pi, Xiaoqing and Iijima, Byron},
  title = {Advection of the equatorial anomaly over Arecibo by small-storm related disturbance dynamo electric fields},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2833-2836},
  url = {http://dx.doi.org/10.1029/2000GL000025},
  doi = {10.1029/2000GL000025}
}
Bishop RL, Earle GD, Herrero FA and Bateman TT (2000), "Observations of an intermediate layer during the Coqui II campaign", Journal of Geophysical Research: Space Physics. Vol. 105(A11), pp. 24963-24971.
Abstract: NASA sounding rocket 21.114, launched March 7, 1998, during the Coqui II campaign, provided neutral wind and plasma density measurements of a weak intermediate layer. The layer was centered near 140 km and had an approximate peak plasma density of 2200 cm-3. The measured winds were typically less than 40 m s-1, in agreement with wind shear formation theory and coincident density observations. The data obtained during the flight allow us to explore the plasma density structure and wind field morphology of the intermediate layer. Coupled with simultaneous data from Arecibo Observatory, the upleg and downleg density profiles provide three spatially separated measurements that enable the first detailed investigation of the horizontal extent and variation of an intermediate layer.
BibTeX:
@article{Bishop2000,
  author = {Bishop, R. L. and Earle, G. D. and Herrero, F. A. and Bateman, T. T.},
  title = {Observations of an intermediate layer during the Coqui II campaign},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A11},
  pages = {24963-24971},
  url = {http://dx.doi.org/10.1029/1999JA000453},
  doi = {10.1029/1999JA000453}
}
Bust GS, Coco D and Makela JJ (2000), "Combined Ionospheric Campaign 1: Ionospheric tomography and GPS total electron count (TEC) depletions", Geophysical Research Letters. Vol. 27(18), pp. 2849-2852.
Abstract: Results from the June 1998 combined ionospheric campaign (CIC) are presented. The CIC represents an attempt to focus a large number of different instruments on one interesting geophysical region. The Center for Ionospheric Research (CIR) at Applied Research Laboratories, the University of Texas at Austin (ARL:UT), has had several computerized ionospheric tomography (CIT) receivers deployed in the Caribbean region since July 1997. In this paper we compare CIT data, GPS TEC data and data from the incoherent scatter radar at Arecibo to try to obtain an understanding of the temporal and spatial distribution of ionospheric structure observed during the campaign. We use the three data sets as inputs to the 3DVAR tomography algorithm developed at CIR and present results of the 3DVAR “objectively analyzed” electron density field. An ionization wall was found near 40° latitude in agreement with previous Millstone Hill and DMSP observations in high Kp. Several elongated density depletions were also detected.
BibTeX:
@article{Bust2000,
  author = {Bust, Gary S. and Coco, David and Makela, Jonathan J.},
  title = {Combined Ionospheric Campaign 1: Ionospheric tomography and GPS total electron count (TEC) depletions},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2849-2852},
  url = {http://dx.doi.org/10.1029/2000GL000053},
  doi = {10.1029/2000GL000053}
}
Cheung PY, Sulzer MP, DuBois DF and Russell DA (2000), "High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. II. Low duty cycle, altitude-resolved, observations", Physics of Plasmas. Vol. 8, pp. 802-812.
Abstract: This is the second of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbulence induced in the ionosphere by a new, more powerful, high frequency heater operated at very low duty cycles. Altitude resolution of 150 m in incoherent scatter radar spectra is made possible by the coded-long-pulse method. Here we present the first observation at Arecibo of the well-developed parametric decay instability and the Langmuir decay instability cascade features in the Thomson scatter radar power spectrum, of the plasma line, at the unmodified matching altitudes under near-cold start conditions. The dependence of the plasma line spectra on altitude, pump power, and density scale length have been studied. The temporal growth and saturation of the spectra during heating and the decay of the spectra in the afterglow of heating has also been studied in detail. Comparisons are made here with the theoretical predictions of the companion paper I [DuBois et al., Phys. Plasmas 8, 791 (2001)]. From these comparisons and a comparison with recent observations at both Arecibo and TromsÜ, we conclude that all the predictions of modern Langmuir turbulence theory for the radar spectral signatures of the turbulence in a smooth ionosphere have now been verified
BibTeX:
@article{Cheung2000,
  author = {P. Y. Cheung and M. P. Sulzer and D. F. DuBois and D. A. Russell},
  title = {High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. II. Low duty cycle, altitude-resolved, observations},
  journal = {Physics of Plasmas},
  year = {2000},
  volume = {8},
  pages = {802-812},
  url = {http://dx.doi.org/10.1063/1.1345704},
  doi = {10.1063/1.1345704}
}
DuBois DF, Russell DA, Cheung PY and Sulzer MP (2000), "High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. I. Theoretical predictions for altitude-resolved plasma line radar spectra", Physics of Plasmas. Vol. 8, pp. 791-801.
Abstract: This is the first of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbulence induced in the ionosphere by a powerful high-frequency (hf) heater operated at very low duty cycles. As shown in paper II [Cheung et al., Phys. Plasmas 8, 802 (2001)], higher power enabled the first observation at Arecibo of the well-developed decay-cascade features in the Thomson scatter radar power spectrum at the unmodified matching altitudes. New theoretical predictions are presented here for the parameters of these observations emphasizing the altitude and pump power dependence of the radar spectra and the time dependence of the spectra from the decaying spectra following heater switch-off. Further details of the strong turbulence signatures from higher altitudes are also presented. At the lower matching altitudes the increase, with hf power, of the angular width of the well-developed decay-cascade spectrum allows these spectral features to come into the view of the Arecibo radar. The favorable comparison of the simulation predictions and observations is discussed in the second paper
BibTeX:
@article{DuBois2000,
  author = {D. F. DuBois and D. A. Russell and P. Y. Cheung and M. P. Sulzer},
  title = {High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. I. Theoretical predictions for altitude-resolved plasma line radar spectra},
  journal = {Physics of Plasmas},
  year = {2000},
  volume = {8},
  pages = {791-801},
  url = {http://dx.doi.org/10.1063/1.1345703},
  doi = {10.1063/1.1345703}
}
Earle GD, Bishop RL, Collins SC, Gonzalez SA and Sulzer MP (2000), "Descending layer variability over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 105(A11), pp. 24951-24961.
Abstract: Descending layers of ionization over Arecibo exhibit very diverse behavior from night to night that does not appear to be strongly correlated to geomagnetic activity, solar forcing, or average semidiurnal tidal winds. On some nights, three or more distinct layers are observed to form near 170 km over timescales of ~2 hours. Rather than descending smoothly over periods of several hours, these layers stall, abruptly disappear, or even reverse direction in the midst of their descent. The time scales for their disappearance are examined and compared to loss rates arising from diffusion and recombination. Diffusion alone is found to be too slow to account for the observations, but recombination is fast enough provided that the convergent wind shear that forms the layer is relatively weak coincident with their disappearance. The continuity equation is solved in conjunction with a time sequence of radar profiles to estimate the vertical drift and horizontal neutral wind consistent with the observed behavior. The resultant wind field is northward, has an average speed of ~80 m s-1, and varies significantly near the altitude where the layers are observed. These inferred winds are consistent with the presence of the observed layers, and their magnitudes as obtained from the classical continuity and momentum equations are reasonable for this altitude range.
BibTeX:
@article{Earle2000,
  author = {Earle, G. D. and Bishop, R. L. and Collins, S. C. and Gonzalez, S. A. and Sulzer, M. P.},
  title = {Descending layer variability over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A11},
  pages = {24951-24961},
  url = {http://dx.doi.org/10.1029/2000JA000029},
  doi = {10.1029/2000JA000029}
}
Earle GD, Kane TJ, Pfaff RF and Bounds SR (2000), "Ion layer separation and equilibrium zonal winds in midlatitude sporadic E", Geophysical Research Letters. Vol. 27(4), pp. 461-464.
Abstract: In-situ observations of a moderately strong midlatitude sporadic-E layer show a separation in altitude between distinct sublayers composed of Fe+, Mg+, and NO+. From these observations it is possible to estimate the zonal wind field consistent with diffusive equilibrium near the altitude of the layer. The amplitude of the zonal wind necessary to sustain the layer against diffusive effects is less than 10 m/s, and the vertical wavelength is less than 10 km.
BibTeX:
@article{Earle2000a,
  author = {Earle, G. D. and Kane, T. J. and Pfaff, R. F. and Bounds, S. R.},
  title = {Ion layer separation and equilibrium zonal winds in midlatitude sporadic E},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {461-464},
  url = {http://dx.doi.org/10.1029/1999GL900572},
  doi = {10.1029/1999GL900572}
}
Friedman JS, Gonzalez SA, Tepley CA, Zhou Q, Sulzer MP, Collins SC and Grime BW (2000), "Simultaneous atomic and ion layer enhancements observed in the mesopause region over Arecibo during the Coqui II Sounding Rocket Campaign", Geophysical Research Letters. Vol. 27(4), pp. 449-452.
Abstract: The NASA Coqui II sounding rocket campaign in Puerto Rico provided the opportunity to obtain a large number of lidar and incoherent scatter radar observations of atomic sodium and ion layers in the upper mesosphere and lower thermosphere. Sodium layer enhancements, coupled with ion layers, were frequently observed in the range of 90–105 km altitude. We found that above 97 km all of the enhanced Na layers were observed to have an associated ion layer, and below that altitude some Na enhancements could occur in their absence. Finally, we show one extraordinary case of a sporadic Na layer that grew to near its peak concentration before the associated ion layer appeared at its altitude.
BibTeX:
@article{Friedman2000,
  author = {Friedman, J. S. and Gonzalez, S. A. and Tepley, C. A. and Zhou, Q. and Sulzer, M. P. and Collins, S. C. and Grime, B. W.},
  title = {Simultaneous atomic and ion layer enhancements observed in the mesopause region over Arecibo during the Coqui II Sounding Rocket Campaign},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {449-452},
  url = {http://dx.doi.org/10.1029/1999GL900605},
  doi = {10.1029/1999GL900605}
}
Garcia FJ, Kelley MC, Makela JJ and Huang C-S (2000), "Airglow observations of mesoscale low-velocity traveling ionospheric disturbances at midlatitudes", Journal of Geophysical Research: Space Physics. Vol. 105(A8), pp. 18407-18415.
Abstract: This paper presents a summary of 630.0 nm emission observations made by the Cornell All-Sky Imager that have revealed an abundance of structure in the midlatitude thermosphÕre. Some events were so bright that the weaker 557.7 nm thermospheric line was readily visible and produced sharper images because of the shorter excitation lifetime. Global Positioning System observations show that the airglow features are traveling ionospheric disturbances (TIDs). The remarkable feature of the data is the overwhelming tendency for these low-velocity TIDs to develop with a northwest to southeast orientation and to propagate in the southwest direction. Speeds ranged from 50 to 170 m/s, and wavelengths ranged from 50 to 500 km. The Perkins instability is investigated as a possible explanation for the structures. The linear theory, including both winds and electric fields, predicts a positive but small growth rate. However, the real part of the dispersion relation gives the wrong sign for the wave propagation. Furthermore, the growth rate seems too small to amplify a seed gravity wave significantly during one period of neutral gas oscillation. We conclude that this class of low-velocity TID is not yet explained theoretically.
BibTeX:
@article{Garcia2000,
  author = {Garcia, F. J. and Kelley, M. C. and Makela, J. J. and Huang, C.-S.},
  title = {Airglow observations of mesoscale low-velocity traveling ionospheric disturbances at midlatitudes},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A8},
  pages = {18407-18415},
  url = {http://dx.doi.org/10.1029/1999JA000305},
  doi = {10.1029/1999JA000305}
}
Garcia FJ, Kelley MC, Makela JJ, Sultan PJ, Pi X and Musman S (2000), "Mesoscale structure of the midlatitude ionosphere during high geomagnetic activity: Airglow and GPS observations", Journal of Geophysical Research: Space Physics. Vol. 105(A8), pp. 18417-18427.
Abstract: On the night of November 22, 1997, the Cornell All-Sky Imager recorded a spectacular display of structure in the 630.0 nm emission over Arecibo, Puerto Rico. This event is an example of a phenomenon we have termed “intense midlatitude spread F.” In this paper we describe the stormtime geophysical conditions for the period and detail the evolution of the event. The daytime midlatitude ionosphere was disturbed for four consecutive days. The initial daytime doubling of the total electron content (TEC) was associated with equatorward propagation of a high-TEC patch that seemed to have associated composition changes. The following days had distinct diurnal double maxima (DDM). The TEC in the Caribbean was very high during the first night of the storm and was extremely structured. Airglow depletions and enhancements surged poleward, bifurcating numerous times in the process. The airglow depletions were collocated with TEC minima along similar lines of sight to Global Positioning System satellites. Eventually, four parallel and very similar airglow wave packets were visible and oriented at an angle similar to the less violent structures reported in the companion paper [Garcia et al., this issue] and moving slowly toward the southwest. We explore a number of possible explanations for these features. We are most confident that secondary instabilities of the generalized ExB process can explain the evolution of the structures once they are formed. The initial process itself remains controversial.
BibTeX:
@article{Garcia2000a,
  author = {Garcia, F. J. and Kelley, M. C. and Makela, J. J. and Sultan, P. J. and Pi, X. and Musman, S.},
  title = {Mesoscale structure of the midlatitude ionosphere during high geomagnetic activity: Airglow and GPS observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A8},
  pages = {18417-18427},
  url = {http://dx.doi.org/10.1029/1999JA000306},
  doi = {10.1029/1999JA000306}
}
Hecht JH, Collins S, Kruschwitz C, Kelley MC, Roble RG and Walterscheid RL (2000), "The excitation of the Na airglow from Coqui Dos rocket and ground-based observations", Geophysical Research Letters. Vol. 27(4), pp. 453-456.
Abstract: On February 20 1998 two rockets were launched from Puerto Rico as part of the Coqui Dos campaign. Data from on-board photometers and ground-based data from a Na lidar and an airglow imager allowed an estimate to be made, using both the TIME-GCM and MSIS models, of the branching coefficient alpha for the Na airglow emission. Assuming the hydrogen density is within the range predicted by the two models the data are consistent with alpha being less than 0.05. This value is well below a recent theoretical estimate of 0.67 and also below the nominally accepted value of 0.1 derived from previous aeronomic data.
BibTeX:
@article{Hecht2000,
  author = {Hecht, J. H. and Collins, S. and Kruschwitz, C. and Kelley, M. C. and Roble, R. G. and Walterscheid, R. L.},
  title = {The excitation of the Na airglow from Coqui Dos rocket and ground-based observations},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {453-456},
  url = {http://dx.doi.org/10.1029/1999GL010853},
  doi = {10.1029/1999GL010853}
}
Isham B, Tepley CA, Sulzer MP, Zhou QH, Kelley MC, Friedman JS and Gonzalez SA (2000), "Upper atmospheric observations at the Arecibo Observatory: Examples obtained using new capabilities", Journal of Geophysical Research. Vol. 105({A8}), pp. 18609-18637.
Abstract: The Arecibo Observatory will soon complete a major instrumental upgrade which will provide improved capabilities for observations of the upper atmosphere. As in the past, Arecibo capabilities center on 430-MHz incoherent scatter radar (ISR) measurements of the ionosphere made locally or in conjunction with other national and international incoherent scatter facilities; the upgrade will add the capability for simultaneous two beam incoherent scatter observations and will extend plasma line measurements to ±15 MHz. Aeronomical studies may also be performed using a 46.8-MHz coherent scatter radar, the feed of which is coaxial with the 430-MHz line feed, the newly refurbished medium-frequency (MF) radar facility, and a new digital ionosonde. The original airglow laboratory continues to house the Fabry-Perot interferometers, Ebert-Fastie spectrometer, and tilting filter photometers used for observations of mesospheric, thermospheric, and exospheric airglow, while a new laboratory provides a permanent home for the lidars used for resonance fluorescence observations of atomic metal layers in the mesopause region and for Doppler Rayleigh measurements of the upper stratosphere and lower mesosphere. Finally, the recently upgraded high-frequency, high-power transmitter facility has performed active aeronomical and plasma physical studies alone and in conjunction with other Arecibo and visitor-supplied instruments. Observations performed as the upgrade nears completion have already provided a first look at what lies ahead in areas as diverse and fundamental as the structure and dynamics of the turbopause, the properties of upper atmospheric tides, the electrodynamics of the E and F regions, the dynamics of light ions in the topside, and the physics of plasma turbulence. Examples of these and other observations are presented, and the opportunities for future investigations are discussed.
BibTeX:
@article{Isham2000,
  author = {B. Isham and C. A. Tepley and M. P. Sulzer and Q. H. Zhou and M. C. Kelley and J. S. Friedman and S. A. Gonzalez},
  title = {Upper atmospheric observations at the Arecibo Observatory: Examples obtained using new capabilities},
  journal = {Journal of Geophysical Research},
  year = {2000},
  volume = {105},
  number = {A8},
  pages = {18609-18637},
  url = {http://dx.doi.org/10.1029/1999JA900315},
  doi = {10.1029/1999JA900315}
}
Janches D, Mathews JD, Meisel DD and Zhou Q-H (2000), "Micrometeor Observations Using the Arecibo 430 MHz Radar: I. Determination of the Ballistic Parameter from Measured Doppler Velocity and Deceleration Results", Icarus. Vol. 145, pp. 53-63. Elsevier Science.
Abstract: We present a sample of radar meteors detected during the November 1997 Leonids shower period using the narrow-beam, high-power Arecibo Observatory 430-MHz radar. During this period ~7700 events were detected over 73 h of observations that included six mornings. Near apex-crossing, 6–10 events per minute were observed in the ~300-m diameter beam. From these events a total of 390 meteors are characterized by a clear linear deceleration as derived from the radial Doppler speed determined from the meteor-echo leading-edge (head-echo). We interpret our results in terms of the meteor ballistic parameter—the ratio of the meteoroid mass to cross-sectional area—yielding a physical characterization of these particles prior to any assumptions regarding meteoroid shape and mass density. In addition, we compare these measurements with the results of a numerical solution of the meteor deceleration equation and find them in good agreement. The size and dynamical mass of the meteoroids are estimated considering these particles to be spheres with densities of 3 g/cm3. We also discuss atmospheric energy-loss mechanisms of these meteroids. We believe these are the first radar meteor decelerations detected since those ones reported by J. V. Evans (1966, J. Geophys. Res. 71, 171–188) and F. Verniani (1966, J. Geophys. Res. 71, 2749–2761; 1973, J. Geophys. Res. 78, 8429–8462) and the first ones for meteors of this size.
BibTeX:
@article{Janches2000,
  author = {Janches, D. and Mathews, J D and Meisel, D D and Zhou, Q-H},
  title = {Micrometeor Observations Using the Arecibo 430 MHz Radar: I. Determination of the Ballistic Parameter from Measured Doppler Velocity and Deceleration Results},
  journal = {Icarus},
  publisher = {Elsevier Science},
  year = {2000},
  volume = {145},
  pages = {53-63},
  url = {http://dx.doi.org/10.1006/icar.1999.6330},
  doi = {10.1006/icar.1999.6330}
}
Kagan LM, Kelley MC, Garcia F, Bernhardt PA, Djuth FT, Sulzer MP and Tepley CA (2000), "The Structure of Electromagnetic Wave-Induced 557.7-nm Emission Associated with a Sporadic-E Event over Arecibo", Physical Review Letters. Vol. 85, pp. 218-221.
Abstract: We report observations of electromagnetic wave-induced 557.7-nm emission in correspondence with a sporadic low-altitude plasma layer (the sporadic- E layer, Es). We show that the structure of 557.7-nm emission seen for some events results from a transformation of transmitted energy by ionization clouds, compiling the patchy type Es, and presents a projection of the sporadic- E layer structure on the emission altitude. This allows us to propose the first method for visualizing a horizontal structure of sporadic- E layers.
BibTeX:
@article{Kagan2000,
  author = {Kagan, L. M. and Kelley, M. C. and Garcia, F. and Bernhardt, P.~A. and Djuth, F. T. and Sulzer, M. P. and Tepley, C. A.},
  title = {The Structure of Electromagnetic Wave-Induced 557.7-nm Emission Associated with a Sporadic-E Event over Arecibo},
  journal = {Physical Review Letters},
  year = {2000},
  volume = {85},
  pages = {218-221},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.85.218},
  doi = {10.1103/PhysRevLett.85.218}
}
Kagan LM and Kelley MC (2000), "A thermal mechanism for generation of small-scale irregularities in the ionospheric E region", Journal of Geophysical Research: Space Physics. Vol. 105(A3), pp. 5291-5303.
BibTeX:
@article{Kagan2000a,
  author = {Kagan, L. M. and Kelley, M. C.},
  title = {A thermal mechanism for generation of small-scale irregularities in the ionospheric E region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A3},
  pages = {5291-5303},
  doi = {10.1029/1999JA900415}
}
Kelley MC, Makela JJ, Saito A, Aponte N, Sulzer M and Gonzalez SA (2000), "On the electrical structure of airglow depletion/Height layer bands over Arecibo", Geophysical Research Letters. Vol. 27(18), pp. 2837-2840.
Abstract: Using a combination of airglow images and incoherent scatter radar data, we have explored the electrical structure of the airglow depleted, height layer bands over a mid-latitude site. We find a reproducible electrical signature in both components of the electric field in all events studied. The most pronounced feature is a large northward/upward electric field in the heart of the structure. The latter is identical to the radially outward field reported for mid-latitude conjugate electric fields [Saito et al., 1995], found to trace the poleward edge of the equatorial anomaly. We favorably compare the Arecibo drift to a typical satellite event. These electric fields may reflect a nonlinear evolved state of the Perkins instability or some, as yet, unexplained coupling between atmospheric motion and the plasma embedded in it. We show here that the F-region Pedersen conductivity is much lower in these structures than outside and suggest that this is related to a polarization electric field inside the structure.
BibTeX:
@article{Kelley2000,
  author = {Kelley, Michael C. and Makela, Jonathan J. and Saito, Akinori and Aponte, Nestor and Sulzer, Michael and Gonzalez, Sixto A.},
  title = {On the electrical structure of airglow depletion/Height layer bands over Arecibo},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2837-2840},
  url = {http://dx.doi.org/10.1029/2000GL000024},
  doi = {10.1029/2000GL000024}
}
Kelley MC and Gelinas LJ (2000), "Gradient drift instability in midlatitude sporadic E layers: Localization of physical and wavenumber space", Geophysical Research Letters. Vol. 27(4), pp. 457-460.
Abstract: Ionospheric plasmas containing density gradients are subject to a gradient drift instability under the influence of an externally applied electric field or neutral wind. In this paper we present electric field wave data from the Sudden Atom Layers sounding rocket showing a pure gradient drift instability on the topside of a 1 km thick sporadic E layer. An outer scale of 50 m was determined. Considering the local linear growth rate and the mapping of the electric field structures along magnetic field lines, we conclude that structures with scales larger than 50 m perpendicular to the magnetic field map into regions of linear stability where they are damped. The free energy is localized in wavenumber space, yielding peak fluctuating fields of 6 mV/m, corresponding to electron drifts over 190 m/s and a cascade of energy to meter scales.
BibTeX:
@article{Kelley2000a,
  author = {Kelley, M. C. and Gelinas, L. J.},
  title = {Gradient drift instability in midlatitude sporadic E layers: Localization of physical and wavenumber space},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {457-460},
  url = {http://dx.doi.org/10.1029/1999GL900604},
  doi = {10.1029/1999GL900604}
}
Kelley MC, Garcia F, Makela J, Fan T, Mak E, Sia C and Alcocer D (2000), "Highly structured tropical airglow and TEC signatures during strong geomagnetic activity", Geophysical Research Letters. Vol. 27(4), pp. 465-468.
Abstract: A remarkable set of all-sky images using the 630 nm airglow emission has been taken over the Arecibo Observatory in Puerto Rico. Wave-like structures at a height of about 250 km are commonly found to travel in the southwest direction at speeds ranging from 20–120 m/s. Most surprising is that geomagnetic activity seems to greatly amplify them, forming very intricate patterns of light and dark. Simultaneous observations using GPS satellite transmissions on one night reveal that dark regions are severely plasma depleted while bright regions have nighttime content as large as the full noontime ionosphere. This unexpected geomagnetic effect at mid-latitudes has implications for trans-ionospheric radiowave propagation and Space Weather.
BibTeX:
@article{Kelley2000b,
  author = {Kelley, M. C. and Garcia, F. and Makela, J. and Fan, T. and Mak, E. and Sia, C. and Alcocer, D.},
  title = {Highly structured tropical airglow and TEC signatures during strong geomagnetic activity},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {465-468},
  url = {http://dx.doi.org/10.1029/1999GL900598},
  doi = {10.1029/1999GL900598}
}
Kelley MC, Makela JJ, Swartz WE, Collins SC, Thonnard S, Aponte N and Tepley CA (2000), "Caribbean Ionosphere Campaign, year one: Airglow and plasma observations during two intense mid-latitude spread-F events", Geophysical Research Letters. Vol. 27(18), pp. 2825-2828.
Abstract: A series of campaigns has been carried out in the Caribbean over a one-year period to study intense mid-latitude spread-F events using a cluster of diversified instrumentation. These events are relatively rare but a number of them have now been captured and will be discussed in this and several companion papers. This paper focuses on 630 nm airglow images obtained by the Cornell All-Sky Imager for two of the more spectacular cases that began on February 17, 1998 and February 17, 1999. In the latter case, and for the first time, a poleward surge of depletion/enhancement airglow zones was captured by radar as well as an airglow imager. In the former case structures grew in place overhead and produced strong VHF F-region backscatter as observed by the CUPRI and University of Illinois radars; the other event, exactly one year later, did not result in detectable 3-m backscatter. The two data sets show quantitatively that the low airglow region is elevated in height and depleted in plasma density and Pedersen conductivity. We suggest an enhanced eastward electric field inside the low conductivity zone may be responsible for the surge. The data also suggest small scale turbulence can only be observed in developing structures.
BibTeX:
@article{Kelley2000c,
  author = {Kelley, Michael C. and Makela, Jonathan J. and Swartz, Wesley E. and Collins, Stephen C. and Thonnard, Stefan and Aponte, Nestor and Tepley, Craig A.},
  title = {Caribbean Ionosphere Campaign, year one: Airglow and plasma observations during two intense mid-latitude spread-F events},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2825-2828},
  url = {http://dx.doi.org/10.1029/2000GL000022},
  doi = {10.1029/2000GL000022}
}
Lancaster RS, Waldrop LS, Kerr RB, Noto J, Solomon SC, Tepley CA, Garcia R and Friedman J (2000), "Brightness measurements of the nighttime O I 8446 å airglow emission from the Millstone Hill and Arecibo Observatories", Journal of Geophysical Research: Space Physics. Vol. 105(A3), pp. 5275-5290.
Abstract: Ground-based measurements of the O I 8446 å airglow brightness are made from the Millstone Hill and Arecibo Observatories. These measurements are made at various times throughout the year, and this paper reports those made between the years of 1993 and 1996. The maximum brightness of the 8446 å airglow emission is found to be less than about 35 Rayleighs during the nighttime at both these midlatitude sites. During the summer this emission is present for only a short time in the evening and morning. During the winter the emission can persist throughout the night. This observed behavior is in agreement with the calculations of current models that predict similar intensities from excitation by photoelectron impact on atomic oxygen. A close examination of these data, however, reveal that differences exist between the model predictions and the measured brightness. One difference is a persistence of the nighttime 8446 å brightness to times when the model predicts little or no emission from photoelectron production. A second difference is an occasional enhancement of the morning 8446 å brightness that is not predicted by the model. The former of these differences implies a shortcoming in current understanding of the 8446 å production mechanisms and must be resolved before atomic oxygen can be monitored from the ground using this emission. The latter may have important consequences for our understanding of upper atmosphere dynamics.
BibTeX:
@article{Lancaster2000,
  author = {Lancaster, Redgie S. and Waldrop, Laura S. and Kerr, Robert B. and Noto, John and Solomon, Stanley C. and Tepley, Craig A. and Garcia, Raul and Friedman, Jonathan},
  title = {Brightness measurements of the nighttime O I 8446 å airglow emission from the Millstone Hill and Arecibo Observatories},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A3},
  pages = {5275-5290},
  url = {http://dx.doi.org/10.1029/1999JA900410},
  doi = {10.1029/1999JA900410}
}
Larsen MF (2000), "Coqui 2: Mesospheric and lower thermospheric wind observations over Puerto Rico", Geophysical Research Letters. Vol. 27(4), pp. 445-448.
Abstract: During the 1998 Coqui 2 sounding rocket campaign, three chemical release rockets were launched from Puerto Rico to measure the wind profiles in the mesosphere and lower thermosphere region. The first release took place on February 19, and the next two releases were five days later and four hours apart. All three measurements show large winds and wind shears in the altitude range between 95 and 110 km. The largest wind speeds occurred near 100 km with horizontal flow velocities close to 150 m s-1. Taken in isolation, such features may appear to be unusual, but in fact, a large number of earlier rocket measurements show wind features similar to those observed in the Coqui 2 campaign. Such large winds are therefore not an isolated but rather a common feature of the wind profiles at midlatitudes in an altitude range that is critical for the electrodynamics of the ionosphere. The wind profile characteristics described here are not generally well known since the earlier more extensive chemical release data sets were only published in reports with a rather limited distribution.
BibTeX:
@article{Larsen2000,
  author = {Larsen, M. F.},
  title = {Coqui 2: Mesospheric and lower thermospheric wind observations over Puerto Rico},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {4},
  pages = {445-448},
  url = {http://dx.doi.org/10.1029/1999GL010704},
  doi = {10.1029/1999GL010704}
}
MacPherson B, Gonzalez SA, Sulzer MP, Bailey GJ, Djuth F and Rodriguez P (2000), "Measurements of the topside ionosphere over Arecibo during the total solar eclipse of February 26, 1998", Journal of Geophysical Research: Space Physics. Vol. 105(A10), pp. 23055-23067.
Abstract: The Arecibo incoherent scatter radar facility was operated on February 26, 1998, and was used to observe the total solar eclipse that occurred over the Caribbean. A maximum of 87% obscuration was observed over Arecibo at 1430 LT (1830 UT). The radar was operated using an experimental technique, which uses a 300 ?s single/multi-frequency pulse, to gather data from the altitude range 146–2412 km. The Sheffield University plasmasphere ionosphere model was used to interpret the measurements. The electron temperature was found to have decreased by 600 K at 400 km altitude, but the magnitude of the decrease becomes smaller with increasing altitude. This is shown to be the result of the lesser degree of obscuration of the solar disk at latitudes north of Arecibo. Conjugate point photoelectron heating effects are also shown to play a significant role in the electron energy balance during the eclipse. The H+ ion temperature exhibited a response to the eclipse, with temperatures being around 200 K lower than expected at the time of maximum obscuration. There was relatively little variation observed in the O+ temperature. The response of the topside ionosphere is characterized by a downward motion arising from the contraction of the plasma due to reduced plasma temperatures. This is most clearly seen in the O+-H+ transition altitude which falls by 200 km. The transition altitude fully recovers within 2 hours after the eclipse. The location of the transition altitude acts to mitigate the effects of the eclipse on the topside electron densities.
BibTeX:
@article{MacPherson2000,
  author = {MacPherson, B. and Gonzalez, S. A. and Sulzer, M. P. and Bailey, G. J. and Djuth, F. and Rodriguez, P.},
  title = {Measurements of the topside ionosphere over Arecibo during the total solar eclipse of February 26, 1998},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A10},
  pages = {23055-23067},
  url = {http://dx.doi.org/10.1029/2000JA000145},
  doi = {10.1029/2000JA000145}
}
MacPherson B, Gonzalez SA, Pi X, Kelley M, Bailey GJ, Sulzer MP, Hajj G, Buonsanto M and Wang C (2000), "Comparison between SUPIM simulations and measured TEC for the January, 1997 storm", Geophysical Research Letters. Vol. 27(18), pp. 2845-2848.
Abstract: A method of extrapolating electron densities (Ne) from Incoherent Scatter Radar (ISR) data to high altitudes is presented, and is used to estimate the vertical Total Electron Content (TEC) over Arecibo. Although primarily intended for use on the Ne profiles obtained using the new topside frequency hopping mode at Arecibo which provides measurements to over 2000 km altitude, we show that if the O+ -H+ transition altitude is low enough to be observed, then the method may also be applied to the data taken using the standard World Day multi-radar mode, and thus to a great fraction of the World Day data from low solar flux conditions. This method is applied to Arecibo ISR data taken during the January 6–11 1997 CEDAR storm period, and compared with measured TEC from the Global Positioning System (GPS) satellite network. In addition, the TEC is compared to TEC calculated from the Sheffield University Plasmasphere Ionosphere Model (SUPIM) as part of an ongoing project of model validation.
BibTeX:
@article{MacPherson2000a,
  author = {MacPherson, B. and Gonzalez, S. A. and Pi, X. and Kelley, M. and Bailey, G. J. and Sulzer, M. P. and Hajj, G. and Buonsanto, M. and Wang, C.},
  title = {Comparison between SUPIM simulations and measured TEC for the January, 1997 storm},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2845-2848},
  url = {http://dx.doi.org/10.1029/2000GL000026},
  doi = {10.1029/2000GL000026}
}
Makela JJ, Gonzalez SA, MacPherson B, Pi X, Kelley MC and Sultan PJ (2000), "Intercomparisons of total electron content measurements using the Arecibo Incoherent Scatter Radar and GPS", Geophysical Research Letters. Vol. 27(18), pp. 2841-2844.
Abstract: We compare total electron content measurements made using the Arecibo Incoherent Scatter Radar (ISR) with those made using the Global Positioning System (GPS). The ISR measurements have a limited range for these observations, up to 1500 km. We extend these profiles to GPS heights of 20,200 km with the aid of a numerical model. We use a GPS receiver on St. Croix, which has been calibrated using JPL's Global Ionospheric Mapping (GIM) technique. In addition, we also use the ISR to calibrate GPS measurements made at Isabela, PR and see how the calibration holds up on the next day. The GIM technique gives very good results on both a quiet night and a night with a severe ionospheric depletion. Normalizing the Isabela receiver to the ISR also gives good results and shows promise as a way to independently calibrate nearby GPS receivers in the future. Finally, we give evidence that the severe depletion observed by the ISR on the night of June 25/26, 1998 was associated with an elongated TEC depletion. The structure may be related to a disturbance originating in the southern hemisphere.
BibTeX:
@article{Makela2000,
  author = {Makela, Jonathan J. and Gonzalez, Sixto A. and MacPherson, Bryan and Pi, Xiaoqing and Kelley, Michael C. and Sultan, Peter J.},
  title = {Intercomparisons of total electron content measurements using the Arecibo Incoherent Scatter Radar and GPS},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2841-2844},
  url = {http://dx.doi.org/10.1029/2000GL000023},
  doi = {10.1029/2000GL000023}
}
Pandey VK, Sethi NK and Mahajan KK (2000), "Comparing IRI E-region peak height (hmE) with incoherent scatter data", Advances in Space Research. Vol. 25(1), pp. 65-68.
BibTeX:
@article{Pandey2000,
  author = {Pandey, V K and Sethi, N K and Mahajan, K K},
  title = {Comparing IRI E-region peak height (hmE) with incoherent scatter data},
  journal = {Advances in Space Research},
  year = {2000},
  volume = {25},
  number = {1},
  pages = {65-68},
  doi = {10.1016/S0273-1177(99)00898-4}
}
Pi X, Mendillo M, Hughes WJ, Buonsanto MJ, Sipler DP, Kelly J, Zhou Q, Lu G and Hughes TJ (2000), "Dynamical effects of geomagnetic storms and substorms in the middle-latitude ionosphere: An observational campaign", Journal of Geophysical Research: Space Physics. Vol. 105(A4), pp. 7403-7417.
BibTeX:
@article{Pi2000,
  author = {Pi, Xiaoqing and Mendillo, Michael and Hughes, W. Jeffrey and Buonsanto, Michael J. and Sipler, Dwight P. and Kelly, John and Zhou, Qihou and Lu, Gang and Hughes, Terrence J.},
  title = {Dynamical effects of geomagnetic storms and substorms in the middle-latitude ionosphere: An observational campaign},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {2000},
  volume = {105},
  number = {A4},
  pages = {7403-7417},
  doi = {10.1029/1999JA900460}
}
Raizada S and Sinha HSS (2000), "Some new features of electron density irregularities over SHAR during strong spread F", Annales Geophysicae. Vol. 18(2), pp. 141-151.
Abstract: An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR) (14°N, 80°E, dip latitude 5.5°N) to study electron density and electric field irregularities during spread F. The rocket was launched at 2130 local time (LT) and it attained an apogee of 348 km. Results of electron density fluctuations are presented here. Two extremely sharp layers of very high electron density were observed at 105 and 130 km. The electron density increase in these layers was by a factor of 50 in a vertical extent of 10 km. Large depletions in electron density were observed around 175 and 238 km. Both sharp layers as well as depletions were observed also during the descent. The presence of sharp layers and depletions during the ascent and the descent of the rocket as well as an order of magnitude less electron density, in 150-300 km region during the descent, indicate the presence of strong large-scale horizontal gradients in the electron density. Some of the valley region irregularities (165-178 km), in the intermediate scale size range, observed during this flight, show spectral peaks at 2 km and can be interpreted in terms of the image striation theory suggested by Vickrey et al. The irregularities at 176 km do not exhibit any peak at kilometer scales and appear to be of new type. The growth rate of intermediate scale size irregularities, produced through generalized Rayleigh Taylor instability, was calculated for the 200-330 km altitude, using observed values of electron density gradients and an assumed vertically downward wind of 20 ms-1. These growth rate calculations suggest that the observed irregularities could be produced by the gradient drift instability.
BibTeX:
@article{Raizada2000,
  author = {Raizada, S. and Sinha, H. S. S.},
  title = {Some new features of electron density irregularities over SHAR during strong spread F},
  journal = {Annales Geophysicae},
  year = {2000},
  volume = {18},
  number = {2},
  pages = {141-151},
  url = {http://www.ann-geophys.net/18/141/2000/},
  doi = {10.1007/s00585-000-0141-8}
}
Sinha HSS and Raizada S (2000), "Some new features of ionospheric plasma depletions over the Indian zone using all sky optical imaging", Earth Planets Space. Vol. 52, pp. 549-559.
Abstract: An all sky optical imaging system was operated from Sriharikota rocket range (SHAR) (14° N, 80° E, 5.5° N dip latitude) during January-March, 1993 to observe ionospheric plasma depletions through 630 nm and 777.4 nm night glow emissions. Strong plasma depletions were observed only on four nights viz., 14, 17, 19 and 21 February, 1993. Except the 17 February, which was a magnetically disturbed day, all the other nights pertained to magnetically quiet period. A number of plasma depletion parameters such as, degree of depletion, east-west extent, tilt with respect to the geomagnetic field, inter-depletion distance, drift velocity and plasma enhancements or brightness patterns were estimated. Some of the important results are: (a) It was found that the east-west extent of plasma depletions varied with the degree of depletion; for the 630 nm images the degree of depletion ranged between 6-9% per 100 km east-west extent and for 777.4 nm images it was 3% per 100 km east-west extent, (b) The average inter-depletion distance (IDD) was in the range of 1500±100 km during the magnetically disturbed period and 740±60 km during quiet periods. This is suggestive of gravity wave modulation of the bottom side of the F-region. While the large scale gravity waves (1500±100 km) of auroral origin could be responsible during magnetically disturbed period, smaller scale gravity waves (740±60 km) having their origin in the lower atmosphere could produce initial perturbation in the bottom side of the F-region, (c) Plasma depletions are observed to have an eastward tilt in the range of 10-15° with respect to the geomagnetic field. It has been suggested here that these tilts are associated with the variation of plasma drift with altitude, (d) plasma depletions are observed to be moving eastwards with drift velocities in the range of 40-190 ms-1, and (e) Strong plasma enhancements or brightness patterns were observed on three nights. The degree of enhancement was by a factor of 1.4-3.8. These enhancements lasted for more than 15 minutes. Although, prima facie, these observations look similar to the transient brightness wave reported by Mendillo et al. (1997a), the high degree of enhancement and an extended duration of more than 15 minutes, observed in the present case, need to be understood.
BibTeX:
@article{Sinha2000,
  author = {H. S. S. Sinha and S. Raizada},
  title = {Some new features of ionospheric plasma depletions over the Indian zone using all sky optical imaging},
  journal = {Earth Planets Space},
  year = {2000},
  volume = {52},
  pages = {549-559},
  url = {http://www.terrapub.co.jp/journals/EPS/abstract/5208/52080549.html}
}
Sinha HSS and Raizada S (2000), "First in situ measurement of electric field fluctuations during strong spread F in the Indian zone", Annales Geophysicae. Vol. 18(5), pp. 523-531.
Abstract: An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR) (14°N, 80°E, dip 14°N) along with other experiments, as a part of equatorial spread F (ESF) campaign, to study the nature of irregularities in electric field and electron density. The rocket was launched at 2130 local time (LT) and it attained an apogee of 348 km. Results of vertical and horizontal electric field fluctuations are presented here. Scale sizes of electric field fluctuations were measured in the vertical direction only. Strong ESF irregularities were observed in three regions, viz., 160-190 km, 210-257 km and 290-330 km. Some of the valley region vertical electric field irregularities (at 165 km and 168 km), in the intermediate-scale size range, observed during this flight, show spectral peak at kilometer scales and can be interpreted in terms of the image striation theory suggested by Vickrey et al. The irregularities at 176 km do not exhibit any peak at kilometer scales and appear to be of a new type. Scale sizes of vertical electric field fluctuations showed a decrease with increasing altitude. The most prominent scales were of the order of a few kilometers around 170 km and a few hundred meters around 310 km. Spectra of intermediate-scale vertical electric field fluctuations below the base of the F region (210-257 km) showed a tendency to become slightly flatter (spectral index n = -2.1 ± 0.7) as compared to the valley region (n = -3.6 ± 0.8) and the region below the F peak (n = -2.8 ± 0.5). Correlation analysis of the electron density and vertical electric field fluctuations suggests the presence of a sheared flow of current in 160-330 km region.
BibTeX:
@article{Sinha2000a,
  author = {Sinha, H. S. S. and Raizada, S.},
  title = {First in situ measurement of electric field fluctuations during strong spread F in the Indian zone},
  journal = {Annales Geophysicae},
  year = {2000},
  volume = {18},
  number = {5},
  pages = {523-531},
  url = {http://www.ann-geophys.net/18/523/2000/},
  doi = {10.1007/s00585-000-0523-y}
}
Swartz WE, Kelley MC, Makela JJ, Collins SC, Kudeki E, Franke S, Urbina J, Aponte N, Sulzer MP and Gonzalez SA (2000), "Coherent and incoherent scatter radar observations during intense mid-latitude spread F", Geophysical Research Letters. Vol. 27(18), pp. 2829-2832.
BibTeX:
@article{Swartz2000,
  author = {Swartz, Wesley E. and Kelley, Michael C. and Makela, Jonathan J. and Collins, Stephen C. and Kudeki, Erhan and Franke, Steve and Urbina, Julio and Aponte, Nestor and Sulzer, Michael P. and Gonzalez, Sixto A.},
  title = {Coherent and incoherent scatter radar observations during intense mid-latitude spread F},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2829-2832},
  doi = {10.1029/2000GL000021}
}
Swartz WE, Makela JJ and Kelley MC (2000), "First observations of coherent scatter from the mid-latitude F-region in the Caribbean", Geophysical Research Letters. Vol. 27(7), pp. 935-938.
Abstract: The Cornell University Portable Radar Interferometer (CUPRI) started a new series of measurements of the mid-latitude ionosphere from Puerto Rico in July 1997. On the first day of operation, coherent echoes were obtained from the F region. This was the first detection of such echoes in this longitude sector. This is surprising since the MU radar has seen similar eches over Japan and the presence of related phenomena in the Caribbean suggested they should have been seen in other VHF studies. A number of F-region events were subsequently observed. Some echoes were characterized with very narrow spectra and small mean Doppler shifts. Two events had echoes whose range changed rapidly with time, but only one of these had comparable Doppler velocities. Such differences suggest that we caught the events in different stages of development. In addition to presenting samples of the data, we outline the reasons why these structures were anticipated.
BibTeX:
@article{Swartz2000a,
  author = {Swartz, Wesley E. and Makela, Jonathan J. and Kelley, Michael C.},
  title = {First observations of coherent scatter from the mid-latitude F-region in the Caribbean},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {7},
  pages = {935-938},
  url = {http://dx.doi.org/10.1029/1999GL010741},
  doi = {10.1029/1999GL010741}
}
Urbina J, Kudeki E, Franke SJ, Gonzalez S, Zhou Q and Collins SC (2000), "50 MHz radar observations of mid-latitude E-region irregularities at Camp Santiago, Puerto Rico", Geophysical Research Letters. Vol. 27(18), pp. 2853-2856.
Abstract: A 50 MHz radar interferometer was used near Salinas, Puerto Rico, to probe the meter-scale E-region plasma density irregularities during two campaigns conducted in 1998. During the February–April period E-region echoing layers were primarily observed between 90 and 100 km heights. The layers were typically thin (~1 km) and unstructured, although in several cases short period (~90 s) layer oscillations were observed. During the June-July period E-region echoes showed more varied characteristics. In addition to low altitude layers, quasi-periodic structures with descending echoing layers were observed at altitudes above 100 km. Zonal motions detected during descending layer events were at times variable and oscillated between westward and eastward directions while the layer descent rates remained fixed.
BibTeX:
@article{Urbina2000,
  author = {Urbina, Julio and Kudeki, Erhan and Franke, Steven J. and Gonzalez, Sixto and Zhou, Qihou and Collins, Stephen C.},
  title = {50 MHz radar observations of mid-latitude E-region irregularities at Camp Santiago, Puerto Rico},
  journal = {Geophysical Research Letters},
  year = {2000},
  volume = {27},
  number = {18},
  pages = {2853-2856},
  url = {http://dx.doi.org/10.1029/2000GL000028},
  doi = {10.1029/2000GL000028}
}
Walterscheid RL, Hecht JH, Djuth FT and Tepley CA (2000), "Evidence of reflection of a long-period gravity wave in observations of the nightglow over Arecibo on May 8-9, 1989", Journal of Geophysical Research: Atmospheres. Vol. 105(D5), pp. 6927-6934.
Abstract: During the Arecibo Initiative in Dynamics of the Atmosphere (AIDA) campaign there were several unusual observations of the O2 Atmospheric (0,1) and OH Meinel (6,2) brightness fluctuations being nearly 180° out of phase. In this paper we discuss data from May 8–9, 1989, during which meteor radar and airglow instrumentations were operating and thus wind data were available. We show that the nearly out-of-phase result on this night is due to the fact that the OH Meinel brightness and temperature are out of phase while the O2 atmospheric temperature and brightness are nearly in phase. The characteristics of the wave causing the out of phase fluctuations are derived and comparisons are made between results obtained by the Aerospace nightglow camera and those obtained by the York University airglow camera [Zhang et al., 1993]. Although there are differences between them, both of the instrumental data sets are consistent with the presence of a wave with a horizontal wavelength >=600 km and a period of several hours. An analysis of these data shows that the out-of-phase relationship is most likely due to strong wave reflection in the lower thermosphere caused by thermal gradients and wind shears.
BibTeX:
@article{Walterscheid2000,
  author = {Walterscheid, R. L. and Hecht, J. H. and Djuth, F. T. and Tepley, C. A.},
  title = {Evidence of reflection of a long-period gravity wave in observations of the nightglow over Arecibo on May 8-9, 1989},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2000},
  volume = {105},
  number = {D5},
  pages = {6927-6934},
  url = {http://dx.doi.org/10.1029/1999JD901065},
  doi = {10.1029/1999JD901065}
}
Aponte N, Swartz WE and Farley DT (1999), "Electron energy balance in the F region above Jicamarca", Journal of Geophysical Research: Space Physics. Vol. 104(A5), pp. 10041-10049.
Abstract: Incoherent scatter measurements from Jicamarca, Peru, show that current models and cross sections account quite well for the heating and cooling of F region electrons, in marked contrast to earlier similar studies at low and middle latitudes. The latter showed discrepancies of the order of a factor of 2 between the calculated energy input and loss rates. The equatorial F region ionosphere provides the simplest configuration for such studies because the horizontal magnetic field eliminates vertical photoelectron transport and thermal conduction. We based our estimates of electron heating on photoelectron energy spectra computed from recently developed solar flux models and new absorption and ionization cross sections and included the additional energy source clue to quenching of the 2D metastable state of nitrogen. This extra source is sometimes significant. Electron and ion temperatures and densities measured with the Jicamarca incoherent scatter radar were used to complete the calculations of the heating and cooling rates. We present here data from 2 days, one with low solar activity and one with moderate activity, over the altitude range 220–325 km. The heating/cooling rates ranged from about 500 to 6000 eV cm-3 s-1. Over this entire range the calculated heating and cooling rates differed by 10% or less when the data quality was good.
BibTeX:
@article{Aponte1999,
  author = {Aponte, Nestor and Swartz, Wesley E. and Farley, Donald T.},
  title = {Electron energy balance in the F region above Jicamarca},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1999},
  volume = {104},
  number = {A5},
  pages = {10041-10049},
  url = {http://dx.doi.org/10.1029/1999JA900054},
  doi = {10.1029/1999JA900054}
}
Buonsanto M, Gonzalez SA, Pi X, Ruohoniemi JM, Sulzer MP, Swartz W, Thayer J and Yuan DN (1999), "Radar Chain Study of the May, 1995 Storm", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 61(3-4), pp. 233-248.
BibTeX:
@article{Buonsanto1999,
  author = {Michael Buonsanto and S. A. Gonzalez and X. Pi and J. M. Ruohoniemi and M. P. Sulzer and W. Swartz and J. Thayer and D. N. Yuan},
  title = {Radar Chain Study of the May, 1995 Storm},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {1999},
  volume = {61},
  number = {3-4},
  pages = {233-248},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682698001345},
  doi = {10.1016/S1364-6826(98)00134-5}
}
Buonsanto MJ, Gonzalez SA, Lu G, Reinisch BW and Thayer JP (1999), "Coordinated incoherent scatter radar study of the January 1997 storm", Journal of Geophysical Research: Space Physics. Vol. 104(A11), pp. 24625-24637.
BibTeX:
@article{Buonsanto1999a,
  author = {Buonsanto, M. J. and Gonzalez, S. A. and Lu, G. and Reinisch, B. W. and Thayer, J. P.},
  title = {Coordinated incoherent scatter radar study of the January 1997 storm},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1999},
  volume = {104},
  number = {A11},
  pages = {24625-24637},
  doi = {10.1029/1999JA900358}
}
Buonsanto M (1999), "Ionospheric Storms - A Review", Space Science Reviews. Vol. 88(3-4), pp. 563-601.
BibTeX:
@article{Buonsanto1999b,
  author = {Buonsanto, M.J.},
  title = {Ionospheric Storms - A Review},
  journal = {Space Science Reviews},
  year = {1999},
  volume = {88},
  number = {3-4},
  pages = {563-601},
  doi = {10.1023/A:1005107532631}
}
Carter LN and Forbes JM (1999), "Global transport and localized layering of metallic ions in the upper atmospherere", Annales Geophysicae. Vol. 17(2), pp. 190-209.
BibTeX:
@article{Carter1999,
  author = {Carter, L. N. and Forbes, J. M.},
  title = {Global transport and localized layering of metallic ions in the upper atmospherere},
  journal = {Annales Geophysicae},
  year = {1999},
  volume = {17},
  number = {2},
  pages = {190-209},
  doi = {10.1007/s00585-999-0190-6}
}
Djuth FT, Bernhardt PA, Tepley CA, Gardner JA, Kelley MC, Broadfoot AL, Kagan LM, Sulzer MP, Elder JH, Selcher C, Isham B, Brown C and Carlson HC (1999), "Large airglow enhancements produced via wave-plasma interactions in sporadic E", Geophysical Research Letters. Vol. 26(11), pp. 1557-1560.
BibTeX:
@article{Djuth1999,
  author = {Djuth, F. T. and Bernhardt, P. A. and Tepley, C. A. and Gardner, J. A. and Kelley, M. C. and Broadfoot, A. L. and Kagan, L. M. and Sulzer, M. P. and Elder, J. H. and Selcher, C. and Isham, B. and Brown, C. and Carlson, H. C.},
  title = {Large airglow enhancements produced via wave-plasma interactions in sporadic E},
  journal = {Geophysical Research Letters},
  year = {1999},
  volume = {26},
  number = {11},
  pages = {1557-1560},
  doi = {10.1029/1999GL900296}
}
Franz TL, Kelley MC and Gurevich AV (1999), "Radar backscattering from artificial field-aligned irregularities", Radio Science. Vol. 34(2), pp. 465-475.
Abstract: In June of 1992 a NASA sounding rocket was fired into the Arecibo heater beam to provide in situ observations of artificially induced ionospheric irregularities. In this paper we provide a radar scattering calculation based on in situ data and compare the same with previous remote sensing experiments and with theory. The calculated backscatter cross section is in good agreement with prior observations over the Arecibo heater at 50 MHz. More important, when we scale the observed in situ power spectrum appropriately and compare it with multiradar cross-sectional results from the Platteville, Colorado experiments, we find a remarkably similar radar frequency dependence, albeit one shifted to smaller scales over the higher-latitude site. Even though the rms fluctuation level is almost the same over the Arecibo and Platteville heaters, the shift in scales toward smaller structures over Platteville explains the much larger VHF radar cross section measured there. Comparison of our waveform and its power spectrum with similar predictions from a recent theory shows excellent agreement for k values up to about 5 times the breakpoint in the spectrum of the theoretical prediction. Taken together, these results give very strong evidence for the production of needle-like solitary structures as the dominant final state when high-power radio waves reflect from a magnetized plasma. The organization of these structures by as yet unexplained processes may explain the scales between 10 m and 10 km which occur in the heated volume. Finally, the dominant needle-like field-aligned density depletions seem to support a second source of smaller-scale irregularities. This creates a second break in the power law slope from its one-dimensional value of k-4.3 predicted by theory to one more nearly characterized by k-3. The multiradar results from Platteville show a similar break, and we speculate that a density and/or temperature-gradient-driven instability such as the drift wave is operating.
BibTeX:
@article{Franz1999,
  author = {Franz, T. L. and Kelley, M. C. and Gurevich, A. V.},
  title = {Radar backscattering from artificial field-aligned irregularities},
  journal = {Radio Science},
  year = {1999},
  volume = {34},
  number = {2},
  pages = {465-475},
  url = {http://dx.doi.org/10.1029/1998RS900035},
  doi = {10.1029/1998RS900035}
}
Grime BW, Kane TJ, Collins SC, Kelley MC, Kruschwitz CA, Friedman JS and Tepley CA (1999), "Meteor trail advection and dispersion; Preliminary lidar observations", Geophysical Research Letters. Vol. 26(6), pp. 675-678.
Abstract: Sodium resonance lidar observations of meteor ablation trails at the Arecibo Observatory (18.30°N, 66.75°W) are presented. Of particular interest is the event of 23 March 1998, during the Coqui II sounding rocket campaign. On this date, the lidar was operating with two beams probing different volumes of the sodium layer separated zonally by 15.7±0.8 km. A single meteor trail was observed near 89 km altitude in both lidar field-of-views with a 310±50 s temporal displacement. This observational separation suggested a westward zonal wind of 50±10 m/s, while trail dispersion yielded an upper bound for the total diffusion coefficient of 2.6±0.5 m²/s which is consistent with dispersion seen in other trails. The data supports the need for future observation with systems specialized for meteor detection.
BibTeX:
@article{Grime1999,
  author = {Grime, Brent W. and Kane, Timothy J. and Collins, Stephen C. and Kelley, Michael C. and Kruschwitz, Craig A. and Friedman, Jonathan S. and Tepley, Craig A.},
  title = {Meteor trail advection and dispersion; Preliminary lidar observations},
  journal = {Geophysical Research Letters},
  year = {1999},
  volume = {26},
  number = {6},
  pages = {675-678},
  url = {http://dx.doi.org/10.1029/1999GL900053},
  doi = {10.1029/1999GL900053}
}
Gurevich A, Carlson H, Kelley M, Hagfors T, Karashtin A and Zybin K (1999), "Nonlinear Structuring of the Ionosphere Modified by Powerful Radio Waves at Low Latitudes", Physics Letters A. Vol. 251, pp. 311-321.
Abstract: The problem of the nonlinear structuring of the modified ionosphere due to the self-focusing of the pump wave on the bunches of striations is investigated. Two main conditions of self-focusing are formulated: (1) propagation of the pump wave quite along the magnetic field for effective excitation of striations, and (2) trapping of the pump wave by large-scale irregularities. It is shown that both conditions can be easily satisfied for small inclination angles alpha of the magnetic field to the vertical. A detailed study of the low latitude case was performed using model calculations of the pump wave propagation. It is shown that at low latitudes self-focusing conditions also can be satisfied but mostly for the special form of the large-scale irregularities and mostly in the southern part of the pump wave beam. These results may reconcile apparent differences between radiowave and rocket probing of the irregularities.
BibTeX:
@article{Gurevich1999,
  author = {Gurevich, A. and Carlson, H. and Kelley, M. and Hagfors, T. and Karashtin, A. and Zybin, K.},
  title = {Nonlinear Structuring of the Ionosphere Modified by Powerful Radio Waves at Low Latitudes},
  journal = {Physics Letters A},
  year = {1999},
  volume = {251},
  pages = {311-321},
  url = {http://www.sciencedirect.com/science/article/pii/S0375960198007865},
  doi = {10.1016/S0375-9601(98)00786-5}
}
Isham B, La Hoz C, Rietveld MT, Hagfors T and Leyser TB (1999), "Cavitating Langmuir Turbulence Observed during High-Latitude Ionospheric Wave Interaction Experiments", Physical Review Letters., Sep, 1999. Vol. 83, pp. 2576-2579. American Physical Society.
Abstract: Incoherent scatter radar data obtained during high power radio wave ionospheric interaction experiments performed in northern Scandinavia show an induced spectral line at the O-mode pump frequency simultaneous with strong enhancements at the natural Langmuir resonance frequency, both just below the reflection height. These characteristics provide an unmistakable signature of cavitating (a.k.a. strong) Langmuir turbulence, and show that this turbulence occurs not only in midlatitude but also during high latitude ionospheric interaction experiments. Cavitating turbulence is thus not dependent on specific geophysical conditions but is due to fundamental wave-plasma interaction processes in the ionospheric plasma.
BibTeX:
@article{Isham1999,
  author = {Isham, B. and La Hoz, C. and Rietveld, M. T. and Hagfors, T. and Leyser, T. B.},
  title = {Cavitating Langmuir Turbulence Observed during High-Latitude Ionospheric Wave Interaction Experiments},
  journal = {Physical Review Letters},
  publisher = {American Physical Society},
  year = {1999},
  volume = {83},
  pages = {2576-2579},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.83.2576},
  doi = {10.1103/PhysRevLett.83.2576}
}
Kuo SP and Lee MC (1999), "On the generation of a broad downshifted spectrum of HF wave enhanced plasma lines in the ionospheric heating experiments", Geophysical Research Letters. Vol. 26(21), pp. 3289-3292.
Abstract: Generation of a broad downshifted spectrum of HF wave enhanced plasma Lines (HFPLs) in ionospheric heating experiments is explored. Langmuir waves are first excited within a cone around the geomagnetic field by the HF wave, in the region near its reflection height, through the oscillating two stream instability (OTSI). These Langmuir waves then cascade through a secondary parametric instability, whereby an obliquely propagating Langmuir pump wave decays into an obliquely propagating Langmuir sideband and a lower hybrid decay mode, which propagates in a direction perpendicular to the Langmuir pump wave. The excited Langmuir sidebands have a broad downshifted frequency spectrum and large propagation angles. Their propagation angles are further widened via the filamentation instability or scattering off short-scale field-aligned density irregularities. Thus they become detectable by backscatter radars as HFPLs with a broad downshifted frequency spectrum. The results of our analysis show that it requires HF field amplitude of 3.6 V/m to cascade the OTSI-excited Langmuir waves, for example, 8 times to produce a downshifted spectral width of 50 KHz in the Arecibo heating experiments.
BibTeX:
@article{Kuo1999,
  author = {Kuo, S. P. and Lee, M. C.},
  title = {On the generation of a broad downshifted spectrum of HF wave enhanced plasma lines in the ionospheric heating experiments},
  journal = {Geophysical Research Letters},
  year = {1999},
  volume = {26},
  number = {21},
  pages = {3289-3292},
  url = {http://dx.doi.org/10.1029/1999GL003652},
  doi = {10.1029/1999GL003652}
}
Lee MC, Klien EMC, Burke WJ, Zhang AX, Riddolls RJ, Kuo SP, Sulzer MP and Isham B (1999), "Augmentation of natural ionospheric plasma turbulence by HF heater waves", Geophysical Research Letters. Vol. 26(1), pp. 37-40.
Abstract: HF heating offers a powerful technique for controlled studies of ionospheric plasma turbulence. Heater waves generate large plasma density depletions and sheet-like ionospheric irregularities in the F region, which can give rise to spread F backscatter. Electric fields associated with the induced irregularities can seed plasma instabilities, driven by such environmental causes as density gradients and ambient electric fields, to enhance spread F signatures. Significant reductions in the height-integrated radar backscatter power, measured during the HF heating, indicate the depletion of magnetic flux tubes. Density gradients at the edges of the depletions provide new sources of free energy to augment ionospheric plasma turbulence, enhancing the spread F processes. Furthermore, depleted magnetic flux tubes create and/or alter ionospheric ducts thus affecting radio wave propagation.
BibTeX:
@article{Lee1999,
  author = {Lee, M. C. and Klien, E. M. C. and Burke, W. J. and Zhang, A. X. and Riddolls, R. J. and Kuo, S. P. and Sulzer, M. P. and Isham, B.},
  title = {Augmentation of natural ionospheric plasma turbulence by HF heater waves},
  journal = {Geophysical Research Letters},
  year = {1999},
  volume = {26},
  number = {1},
  pages = {37-40},
  url = {http://dx.doi.org/10.1029/1998GL900266},
  doi = {10.1029/1998GL900266}
}
Peria WJ, Kelley MC and Franz T (1999), "Double-probe measurements in field-aligned irregularities produced by intense electromagnetic radiation", Journal of Geophysical Research: Space Physics. Vol. 104(A4), pp. 6797-6804.
Abstract: We present the signature of filamentary field-aligned irregularities (FAI) in the artificially modified ionosphere using data from a rocket-borne floating double-probe gathered near the critical layer of the Arecibo HF heater beam. We model the double-probe signature as proportional to each filament's density gradient, in the plane perpendicular to the geomagnetic field. We find that this signature is consistent with the presence of a radially directed effective electric field Eeff within each of the over 180 filaments. The direction of Eeffis consistent with that of an ambipolar electric field associated with the rapid perpendicular diffusion of ions out of each filament, or with an apparent electric field due to an inward electron temperature gradient associated with the presence of hotter plasma inside each filament. Our model also gives an estimate of the impact parameter at which each filament is encountered. The mean square impact parameter shows the correct relation to the mean square filament transit time, assuming cylindrical field-aligned filaments. The consistency of these results confirms that the previously reported density depletions are quasi-steady, cylindrically symmetric, spatial structures. A small shift in the apparent angle between the double-probe boom and the filament-rocket velocity places a lower limit on the Earth-frame drift velocity of the filaments, away from the heater beam. Since the filaments are observed near the westward edge of the heater beam, well away from the bulk of the heater Poynting flux, we expect that the filaments are observed in the process of decaying, that is, that ions are diffusing inward rather than outward. Thus we identify Eeff as a temperature gradient and use it to estimate a minimum filament temperature enhancement of ~100 K.
BibTeX:
@article{Peria1999,
  author = {Peria, W. J. and Kelley, M. C. and Franz, T.},
  title = {Double-probe measurements in field-aligned irregularities produced by intense electromagnetic radiation},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1999},
  volume = {104},
  number = {A4},
  pages = {6797-6804},
  url = {http://dx.doi.org/10.1029/1999JA900027},
  doi = {10.1029/1999JA900027}
}
Schubert G, Walterscheid RL, Hickey MP and Tepley CA (1999), "Observations and interpretation of gravity wave induced fluctuations in the O I (557.7 nm) airglow", Journal of Geophysical Research: Space Physics. Vol. 104(A7), pp. 14915-14924.
Abstract: Observations of fluctuations in the intensity and temperature of the O I (557.7 nm) airglow taken at Arecibo in 1989 are reported and interpreted on the assumption that they are caused by gravity waves propagating through the emission layer. The data give the magnitude of Krassovsky's ratio as 3.5 ± 2.2, at periods between about 5 and 10 hours. Comparison with theory shows that the gravity waves responsible for the measured airglow variations must have long wavelengths of several thousand kilometers. The observed phases of Krassovsky's ratio are in good agreement with theoretically predicted values at the long wavelengths and large periods for about half the cases. In the other cases, observed phases are near -180°, suggesting that the waves responsible for the airglow fluctuations have experienced strong reflections in the emission layer. The observations emphasize the importance of knowing the full altitude profiles of temperature and winds for extraction of wave information from the airglow fluctuations.
BibTeX:
@article{Schubert1999,
  author = {Schubert, G. and Walterscheid, R. L. and Hickey, M. P. and Tepley, C. A.},
  title = {Observations and interpretation of gravity wave induced fluctuations in the O I (557.7 nm) airglow},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1999},
  volume = {104},
  number = {A7},
  pages = {14915-14924},
  url = {http://dx.doi.org/10.1029/1999JA900096},
  doi = {10.1029/1999JA900096}
}
Sethi NK, Mahajan KK and Pandey V (1999), "Bottomside Parameters B0, B1 from Arecibo Incoherent Scatter Radar Measurements", Advances in Space Research. Vol. 25(1), pp. 97-100.
Abstract: About 1500 electron density (Ne) profiles observed with the Arecibo incoherent scatter (I.S.) radar have been used to obtain the “best” B0 and B1 parameters by fitting the observed profiles to the IRI bottomside profile function. Seasonal and diurnal variations of these parameters are obtained. The relative difference between the “best fit” profiles and the observed I.S profiles is also studied. This difference is rather small during the night for all the seasons, but is very large during the day, especially during summer and equinox seasons, when an F1 layer is present. About 70 % of the profiles show rather good agreement.
BibTeX:
@article{Sethi1999,
  author = {Sethi, N K and Mahajan, K K and Pandey, V},
  title = {Bottomside Parameters B0, B1 from Arecibo Incoherent Scatter Radar Measurements},
  journal = {Advances in Space Research},
  year = {1999},
  volume = {25},
  number = {1},
  pages = {97-100},
  url = {http://dx.doi.org/10.1016/S0273-1177(99)00903-5},
  doi = {10.1016/S0273-1177(99)00903-5}
}
Sinha HSS, Raizada S and Misra RN (1999), "First simultaneous in situ measurement of electron density and electric field fluctuations during spread F in the Indian Zone", Geophysical Research Letters. Vol. 26(12), pp. 1669-1672.
Abstract: The paper presents results of in situ measurements of electron density and electric field fluctuations (ne, E'v and E'H) during a strong spread F event from the SHAR rocket range in India. Intermediate scale ne irregularities were observed in the F region valley over SHAR, which was earlier found to be free from irregularities. Experimental evidence of the validity of the image striation theory is provided through first simultaneous spectral measurement of electron density and electric field in the valley region. Correlation analysis of ne, E'v and E'H suggests the existence of a sheared flow of current below the F-peak. A new type of irregularity in the intermediate scale having a steep spectrum (n = -3.1) has also been detected in the valley region. A very sharp layer of ionization wherein the electron density increased by a factor of 50 in 10 km vertical extent was detected at 105 km.
BibTeX:
@article{Sinha1999,
  author = {Sinha, H. S. S. and Raizada, Shikha and Misra, R. N.},
  title = {First simultaneous in situ measurement of electron density and electric field fluctuations during spread F in the Indian Zone},
  journal = {Geophysical Research Letters},
  year = {1999},
  volume = {26},
  number = {12},
  pages = {1669-1672},
  url = {http://dx.doi.org/10.1029/1999GL900339},
  doi = {10.1029/1999GL900339}
}
Stening RJ (1999), "The lunar tide in sporadic E", Annales Geophysicae. Vol. 17(10), pp. 1344-1351.
Abstract: It seems that the wind shear theory is accepted for the explanation of sporadic E at mid and low latitudes. Some examples from Arecibo are displayed to show this. The effect of lunar tides should then modify the wind-shear theory in a manner that yields the observed features of the lunar tide in the critical frequency foEs and the height h'Es of the sporadic E. This is shown to imply that the phase of the lunar tide in h'Es should be the same as the phase of the lunar tide in the eastward wind and that the phase of the lunar tide in foEs is three hours later. Hourly values of foEs, f bEs (the blanketing critical frequency) and h'Es from several observatories are analysed for the lunar semidiurnal tide. It is found that the phase of the tide in foEs is often about 3 hours later than for h'Es in agreement with the theory. Seasonal variations in the tide are also examined with the statistically most significant results (largest amplitudes) usually occurring in summer. After reviewing the many difficulties associated with determining the lunar tide in Es, both experimentally and theoretically, the analysed phase results are compared with what might be expected from Hagan's global scale wave model. Agreement is only fair (a success rate of 69% among the cases examined) but probably as good as might be expected.
BibTeX:
@article{Stening1999,
  author = {Stening, R. J.},
  title = {The lunar tide in sporadic E},
  journal = {Annales Geophysicae},
  year = {1999},
  volume = {17},
  number = {10},
  pages = {1344-1351},
  url = {http://www.ann-geophys.net/17/1344/1999/angeo-17-1344-1999.html},
  doi = {10.1007/s00585-999-1344-2}
}
Aponte N (1998), "Radar studies of the equatorial F-region energy balance". Thesis at: CORNELL UNIVERSITY.
BibTeX:
@phdthesis{Aponte1998,
  author = {Aponte, N.},
  title = {Radar studies of the equatorial F-region energy balance},
  school = {CORNELL UNIVERSITY},
  year = {1998},
  url = {http://adsabs.harvard.edu/abs/1998PhDT........40A}
}
Cho JY, Sulzer MP and Kelley MC (1998), "Meteoric dust effects on D-region incoherent scatter radar spectra ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 60(3), pp. 349-357.
Abstract: We extend the incoherent backscatter radar equation for the weakly ionized, collision-dominated case to include polydisperse charged dust, using the fluid-equation approach. Calculations with this equation show that the main effect of charged dust on the radar Doppler spectrum is to narrow it, except in the case of very small, negatively charged dust, which widens the spectrum. The results are encouraging for the use of incoherent scatter radar as an instrument for meteoric dust measurement. We also note that if the effects of meteoric dust are not taken into account, one may get a systematic bias in the D-region parameters deduced from the radar spectra. This may account for the discrepancy between observed and calculated spectra reported in earlier papers.
BibTeX:
@article{Cho1998,
  author = {John Y.N. Cho and Michael P. Sulzer and Michael C. Kelley},
  title = {Meteoric dust effects on D-region incoherent scatter radar spectra },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1998},
  volume = {60},
  number = {3},
  pages = {349-357},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682697001119},
  doi = {10.1016/S1364-6826(97)00111-9}
}
Earle G, Bishop R, Zhou Q and Wallace S (1998), "A comparative study of in-situ and remote intermediate layer measurements against wind model predictions of vertical ion drift", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 60(13), pp. 1313-1330. Elsevier Science.
BibTeX:
@article{Earle1998,
  author = {G.D. Earle and R.L. Bishop and Q.H. Zhou and S.P. Wallace},
  title = {A comparative study of in-situ and remote intermediate layer measurements against wind model predictions of vertical ion drift},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  publisher = {Elsevier Science},
  year = {1998},
  volume = {60},
  number = {13},
  pages = {1313-1330},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682698000819},
  doi = {10.1016/s1364-6826(98)00081-9}
}
Fagundes P, Bittencourt J, Sahai Y, Takahashi H and Teixeira N (1998), "Plasma drifts inferred from thermospheric neutral parameters during geomagnetic storms at 23S", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 60(13), pp. 1303-1311.
Abstract: Nighttime thermospheric neutral winds and temperatures are derived from measurements of Doppler shifts and widths of the OI 630.0 nm airglow emission line, respectively, using a Fabry-Perot interferometer at Cachoeira Paulista (23°S, 45°W, 16°S dip latitude), Brazil. The observed nighttime East-West and North-South temperature gradients and neutral wind velocity variations are presented for two geomagnetic storm periods 7-10 July 1991 and 4-9 August 1991. Zonal plasma drifts inferred during an intense geomagnetic storm, from the nighttime neutral wind velocities and temporal temperature gradient variations, suggested that a strong zonal plasma drift (-240 m/s) on 9-10 July 1991 changed the direction of the zonal winds to westward at 01:30. Also it was noticed that, during the geomagnetic storm, the zonal temperature gradients were not well defined like those observed during quiet time. The meridional wind was towards the pole for the whole night during the geomagnetic storm of 9-10 July, a behaviour which is unusual during winter time (southern hemisphere) at Cachoeira Paulista. However, the meridional plasma drifts inferred did not show significant differences during the quiet and disturbed periods. The method presented to infer plasma drifts using the observed neutral parameters showed results comparable with those observed by incoherent scatter radar measurements at Arecibo.
BibTeX:
@article{Fagundes1998,
  author = {P.R. Fagundes and J.A. Bittencourt and Y. Sahai and H. Takahashi and N.R. Teixeira},
  title = {Plasma drifts inferred from thermospheric neutral parameters during geomagnetic storms at 23S},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1998},
  volume = {60},
  number = {13},
  pages = {1303-1311},
  url = {http://dx.doi.org/10.1016/S1364-6826(98)00075-3},
  doi = {10.1016/S1364-6826(98)00075-3}
}
Gelinas LJ, Lynch KA, Kelley MC, Collins S, Baker S, Zhou Q and Friedman JS (1998), "First observation of meteoritic charged dust in the tropical mesosphere", Geophysical Research Letters. Vol. 25(21), pp. 4047-4050.
Abstract: We discuss a recent sounding rocket experiment which found charged dust in the Earth's tropical mesosphere. The dust detector was designed to measure small (5000–10000 amu) charged dust particles, most likely of meteoric origin. A 5 km thick layer of positively charged dust was found at an altitude of 90 km, in the vicinity of an observed sporadic sodium layer and sporadic E layer. The observed dust was positively charged in the bulk of the dust layer, but was negatively charged near the bottom.
BibTeX:
@article{Gelinas1998,
  author = {Gelinas, L. J. and Lynch, K. A. and Kelley, M. C. and Collins, S. and Baker, S. and Zhou, Q. and Friedman, J. S.},
  title = {First observation of meteoritic charged dust in the tropical mesosphere},
  journal = {Geophysical Research Letters},
  year = {1998},
  volume = {25},
  number = {21},
  pages = {4047-4050},
  url = {http://dx.doi.org/10.1029/1998GL900089},
  doi = {10.1029/1998GL900089}
}
Kelley M, Alcala C and Cho J (1998), "Detection of a meteor contrail and meteoric dust in the Earth's upper mesosphere", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 60(3), pp. 359 - 369.
Abstract: In 1983 a series of small rockets were launched from the Poker Flat Rocket Range near Fairbanks, Alaska to study what has come to be called Polar Mesospheric Summer Echoes (PMSE). We report here on a fortuitous simultaneous 50-MHz radar and rocket detection of what seems to be a meteor contrail produced over the Poker Flat Rocket Range. The two data sets are mutually consistent and taken together suggest some very interesting properties for the trails of large meteors. Most notable is the first evidence that the ablated material can coagulate into particles the order of 50 nm in radius. This estimate is based primarily on the fall speed deduced from both the Doppler shift of the VHG radar signal and the time rate of change of the target as it fell through the beam. In addition the very existence of the radar target, the extremely sharp edges of the trail, and the existence of electron density structures inside the trail more than an order of magnitude smaller than the Kolmogorov microscale, all require large charged aerosols and a very high Schmidt number. Curiously the environment leading to PMSE (the study of which was our primary mission), is very similar to the properties of a large meteor trail some minutes after it is formed. In the PMSE case ice particles grow and become charged by the plasma and, when more than half the charge is tied up on the ice, the plasma diffusion coefficient becomes so small that structure can be supported at VHF scattering scales. In the late-time meteor case large aerosols coagulate and tie up both natural charge in the plasma and the original meteor trail electrons. Following the work of Rosinski and Snow (1961) and Hunten et al. (1980) we conclude that the incident meteor was the order of 100 g and would have had a visual magnitude of about -5. This dust production process may resolve some open questions concerning long-lived meteor radar echoes. For example, in the event studied the electron density was well into the underdense condition and yet was detected for over 6 min. Classical meteor scatter theory has no explanation for such a long duration underdense event.
BibTeX:
@article{Kelley1998,
  author = {M.C. Kelley and C. Alcala and J.Y.N. Cho},
  title = {Detection of a meteor contrail and meteoric dust in the Earth's upper mesosphere},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1998},
  volume = {60},
  number = {3},
  pages = {359 - 369},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682697001132},
  doi = {10.1016/S1364-6826(97)00113-2}
}
Kuo S, Huang J and Lee M (1998), "Parametric excitation of ion Bernstein waves by parallel-propagating langmuir waves in a collisional magnetoplasma", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 60(1), pp. 121-128.
Abstract: Langmuir waves propagating along the geomagnetic field are considered as pump waves for the parametric excitation of ion Bernstein waves and daughter Langmuir waves. Analysis of thresholds and growth rates for the conditions of Arecibo's heating experiments show that ten-meter scale ion Bernstein modes can be preferentially excited. This process competes with others that generate “stationary” (i.e., zero-frequency) density striations in the meter scale range. Limitations on the detection and diagnoses of ion Bernstein modes in the HF heating experiments are discussed.
BibTeX:
@article{Kuo1998121,
  author = {S.P. Kuo and J. Huang and M.C. Lee},
  title = {Parametric excitation of ion Bernstein waves by parallel-propagating langmuir waves in a collisional magnetoplasma},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1998},
  volume = {60},
  number = {1},
  pages = {121-128},
  url = {http://dx.doi.org/10.1016/S1364-6826(97)00073-4},
  doi = {10.1016/S1364-6826(97)00073-4}
}
Lee MC, Riddolls RJ, Burke WJ, Sulzer MP, Kuo SP and Klien EMC (1998), "Generation of large sheet-like ionospheric plasma irregularities at Arecibo", Geophysical Research Letters. Vol. 25(16), pp. 3067-3070.
Abstract: Large-scale ionospheric plasma irregularities, generated by O-mode heater waves at Arecibo, are shown for the first time to have “sheet-like” structures. The irregularities are aligned with the magnetic meridional plane and have scale sizes ranging from a few hundred meters to a few kilometers. This interpretation is based on detailed considerations of sequential measurements of radar backscatter power, the controlling magnetic field geometry, and the deduced E â B plasma drift. The alignment of O-mode-generated irregularities with the magnetic meridional plane, and their disappearance during X-mode heating intervals are consistent with predictions of the thermal filamentation instability model.
BibTeX:
@article{Lee1998,
  author = {Lee, M. C. and Riddolls, R. J. and Burke, W. J. and Sulzer, M. P. and Kuo, S. P. and Klien, E. M. C.},
  title = {Generation of large sheet-like ionospheric plasma irregularities at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1998},
  volume = {25},
  number = {16},
  pages = {3067-3070},
  url = {http://dx.doi.org/10.1029/98GL02322},
  doi = {10.1029/98GL02322}
}
Lee MC, Riddolls RJ, Burke WJ, Sulzer MP, Klien EMC, Rowlands MJ and Kuo SP (1998), "Ionospheric plasma bubble generated by Arecibo heater", Geophysical Research Letters. Vol. 25(5), pp. 579-582.
Abstract: During recent experiments ionospheric plasma bubbles were excited by the upgraded HF heater at Arecibo. These plasma bubbles were observed by radar in the midnight sector with the entire flux tube in darkness. A simple model is outlined to explain the dynamics of density depletions generated during O-mode wave heating of the F layer. We suggest that thermal expansion of plasma away from the heated volume leads to enhanced recombination along the flux tube. In the absence of photoionization sources, density depletions develop along the excited flux tube. The discontinuity of gravity-driven currents at the walls of the depleted region requires development of polarization electric fields. Eastward polarization electric fields of ~2.5 mV/m within the flux tube caused an observed plasma bubble to drift vertically at a speed of 70 m/s.
BibTeX:
@article{Lee1998a,
  author = {Lee, M. C. and Riddolls, R. J. and Burke, W. J. and Sulzer, M. P. and Klien, E. M. C. and Rowlands, M. J. and Kuo, S. P.},
  title = {Ionospheric plasma bubble generated by Arecibo heater},
  journal = {Geophysical Research Letters},
  year = {1998},
  volume = {25},
  number = {5},
  pages = {579-582},
  url = {http://dx.doi.org/10.1029/98GL00327},
  doi = {10.1029/98GL00327}
}
MacPherson B, Gonzales SA, Bailey GJ, Moffett RJ and Sulzer MP (1998), "The effects of meridional neutral winds on the O+-H+ transition altitude over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 103(A12), pp. 29183-29198.
Abstract: Improvements to the way data are taken and analyzed at the Incoherent Scatter Radar Facility at Arecibo, Puerto Rico, mean that the transition altitude, where the O+ and H+ ion densities are equal, can now be studied at all local times throughout the solar cycle. These data show that the diurnal variation of the O+-H+ transition height is characterized by a rapid collapse following sunset, which is associated with the contraction of the plasma due to the rapidly decreasing plasma temperatures at this time. A corresponding increase in the transition altitude is seen at sunrise. The topside data also reveal that a secondary collapse, which is a nonthermal effect, is often observed at local times near midnight. Measurements taken during October 1994 and 1992 are presented and compared to results from the Sheffield University Plasmasphere Ionosphere Model (SUPIM) to study the effect of increasing solar EUV flux on the topside ionosphere. It is shown that SUPIM is able to model reasonably well the sunset and sunrise behavior of the transition altitude. In addition, the secondary collapse of the O+-H+ transition altitude is also studied. It is shown that this secondary collapse may be directly correlated to the well-known “midnight” collapse phenomenon of the F region over Arecibo. The magnitudes of the secondary collapse under low and moderate solar activity are compared, and it is shown that the secondary collapse is less pronounced during solar minimum conditions
BibTeX:
@article{MacPherson1998,
  author = {MacPherson, B and Gonzales, S A and Bailey, G J and Moffett, R J and Sulzer, M P},
  title = {The effects of meridional neutral winds on the O+-H+ transition altitude over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1998},
  volume = {103},
  number = {A12},
  pages = {29183-29198},
  url = {http://dx.doi.org/10.1029/98JA02660},
  doi = {10.1029/98JA02660}
}
Melendez-Alvira DJ, Picone JM, Kelley OA, Zhou Q and Sulzer M (1998), "Histograms of Arecibo World Days Measurements and Linear-H Fits Between 1985 and 1995", NRL/MR/7640-98-8311. Vol. n/a-n/a, pp. n/a-n/a.
Abstract: This document presents histograms of linear-H model fits to electron density profiles measured with the incoherent scatter radar of the Arecibo Observatory in Puerto Rico during the World Days between 1985 and 1995. The linear-H model is a four-parameter analytical function, which is shown to fit the measured electron density profiles with better than 10% accuracy. The histograms show the distribution of the four model parameters as well as statistical measures of the model errors. In addition, the report presents histograms of electron temperature, ratios of electron and ion temperatures, and line-of-sight ion velocities at 589 km. The histograms characterize the ten years of Arecibo World Days, effectively showing a climatology of the actual ranges of both model and topside parameters.
BibTeX:
@article{Melendez-Alvira1998,
  author = {Melendez-Alvira, D J and Picone, J M and Kelley, O A and Zhou, Q and Sulzer, M},
  title = {Histograms of Arecibo World Days Measurements and Linear-H Fits Between 1985 and 1995},
  journal = {NRL/MR/7640-98-8311},
  year = {1998},
  volume = {n/a-n/a},
  pages = {n/a-n/a},
  url = {http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA358383}
}
Nossal S, Roesler FL and Coakley MM (1998), "Cascade excitation in the geocoronal hydrogen Balmer alpha line", Journal of Geophysical Research: Space Physics. Vol. 103(A1), pp. 381-390.
Abstract: This paper reports high-accuracy measurements of geocoronal Balmer &alpha; line profiles and demonstrates that the profiles are well fit with a model which includes cascade excitation by solar Lyman series radiation from n > 3 in addition to the direct excitation of n = 3 by solar Lyman &beta;. The increase in the signal-to-noise of our data is made possible by the use of the Fabry-Perot annular summing technique implemented at our Fabry-Perot facility at the University of Wisconsin's Pine Bluff Observatory. The new sensitivity has allowed us to make a detailed examination of line profile asymmetries and to conclude that they are compatible with predictions that of the order of 10% of the geocoronal Balmer &alpha; emission is caused by the cascade process. Cascade excitation alters the observed profile because it produces Balmer &alpha; emission along fine structure paths yielding slightly shifted wavelengths not present in direct Lyman &beta; excitation, which is the predominant excitation mechanism for geocoronal Balmer &alpha; . We discuss how fine structure excitation affects studies of non-Maxwellian exospheric hydrogen velocity distributions and effective temperatures through Balmer &alpha; line profile measurements. In a broader context, we consider how inclusion of the cascade excited emission in future radiation models can enhance their accuracy and their potential for assisting in the isolation in the data of shorter-term solar geophysical effects and longer timescale changes in exospheric hydrogen densities.
BibTeX:
@article{Nossal1998,
  author = {Nossal, S. and Roesler, F. L. and Coakley, M. M.},
  title = {Cascade excitation in the geocoronal hydrogen Balmer alpha line},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1998},
  volume = {103},
  number = {A1},
  pages = {381-390},
  url = {http://dx.doi.org/10.1029/97JA02435},
  doi = {10.1029/97JA02435}
}
Noto J, Kerr RB, Shea EM, Waldrop LS, Fisher G, Rudy RJ, Hecht JH, Gonzalez SA, Sulzer MP and Garcia R (1998), "Evidence for recombination as a significant source of metastable helium", Journal of Geophysical Research: Space Physics. Vol. 103(A6), pp. 11595-11603.
Abstract: A Fabry-Perot spectrometer optimized for maximum near infrared (NIR) transmission and featuring a germanium detector with a quantum efficiency of 86% at 10,830 å is used to measure the brightness and spectral width of the metastable helium emission in the upper thermosphere. Observations are made at the optical facility associated with the Millstone Hill Incoherent Scatter Radar site in Massachusetts and at the optical facility associated with the Arecibo Observatory in Arecibo, Puerto Rico. Using a spectral resolution of 0.117 å, these are the first observations to isolate the metastable helium triplet 2p3P0,1,2–2s3S1 from nearby OH airglow contamination. Measured 10,830 å brightness decays with shadow in a manner consistent with an emission that is due to resonant scattering of the solar 10,830 å emission. Although the technique we describe was conceived as a powerful tool to measure upper thermospheric and exospheric temperatures, the data indicate a surprising increase of temperature with shadow height to values much greater than commonly ascribed to the near solar minimum thermosphere. We assert that the broad 10,830 å spectral line widths, retrieved when the shadow heights are above ~300 km, are due to a nonthermal metastable helium population. This source of hot, metastable helium is very likely He+ recombination in the twilight. That conclusion is contrary to an historical understanding that the dominant source of metastable helium is the impact of photoelectrons with energies in excess of 19.8 eV with ground state helium.
BibTeX:
@article{Noto1998,
  author = {Noto, J. and Kerr, R. B. and Shea, E. M. and Waldrop, L. S. and Fisher, G. and Rudy, R. J. and Hecht, J. H. and Gonzalez, S. A. and Sulzer, M. P. and Garcia, R.},
  title = {Evidence for recombination as a significant source of metastable helium},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1998},
  volume = {103},
  number = {A6},
  pages = {11595-11603},
  url = {http://dx.doi.org/10.1029/97JA03062},
  doi = {10.1029/97JA03062}
}
Osterman GB, Heelis RA and Bailey GJ (1998), "Effects of wind-induced ionization layers on ionospheric electrodynamics", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 60, pp. 107-113.
BibTeX:
@article{Osterman1998,
  author = {Osterman, G. B. and Heelis, R. A. and Bailey, G. J.},
  title = {Effects of wind-induced ionization layers on ionospheric electrodynamics},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {1998},
  volume = {60},
  pages = {107-113},
  doi = {10.1016/S1364-6826(97)00090-4}
}
Palmer RD, Larsen MF, Howell PB, Narayan RM and Kelley MC (1998), "Correction to “A new spatial interferometry capability using the Arecibo 430-MHz radar” by Robert D. Palmer et al.", Radio Science. Vol. 33(4), pp. 1035-1035.
BibTeX:
@article{Palmer1998,
  author = {Palmer, R D and Larsen, M F and Howell, P B and Narayan, R M and Kelley, M C},
  title = {Correction to “A new spatial interferometry capability using the Arecibo 430-MHz radar” by Robert D. Palmer et al.},
  journal = {Radio Science},
  year = {1998},
  volume = {33},
  number = {4},
  pages = {1035-1035},
  doi = {10.1029/98RS01630}
}
Qiu YH (1998), "A novel design for a giant Arecibo-type spherical radio telescope with an active main reflector", Monthly Notices of the Royal Astronomical Society. Vol. 301(3), pp. 827-830. Blackwell Science Ltd.
Abstract: A novel design for a giant spherical radio telescope is proposed. Instead of a fixed spherical reflecting surface such as with the 305-m Arecibo telescope, the illuminated portion of the reflecting surface is made to fit a paraboloid of revolution in real time by active control. A simple feed can thus be used, enabling the realization of broad bandwidth and full polarization. The actual design utilizes a karst depression which gives a spherical surface of 300-m radius, having an opening of 500-m diameter. The illuminated aperture is chosen to be 300 m, and the focal ratio is 0.46–0.48. With this geometry and the simple feeding system, a giant telescope with large sky coverage can be achieved at low cost. When the illuminated aperture is limited to 70–100 m, the area trackable can be extended to about 10° above the horizon.
BibTeX:
@article{Qiu1998,
  author = {Qiu, Yuhai H.},
  title = {A novel design for a giant Arecibo-type spherical radio telescope with an active main reflector},
  journal = {Monthly Notices of the Royal Astronomical Society},
  publisher = {Blackwell Science Ltd},
  year = {1998},
  volume = {301},
  number = {3},
  pages = {827-830},
  url = {http://dx.doi.org/10.1046/j.1365-8711.1998.02067.x},
  doi = {10.1046/j.1365-8711.1998.02067.x}
}
Showen RL and Slingeland A (1998), "Measuring lightning-induced ionospheric effects with incoherent scatter radar or with cross-modulation", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 60, pp. 951-956.
BibTeX:
@article{Showen1998,
  author = {Robert L. Showen and Alexander Slingeland},
  title = {Measuring lightning-induced ionospheric effects with incoherent scatter radar or with cross-modulation},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1998},
  volume = {60},
  pages = {951-956},
  doi = {10.1016/S1364-6826(98)00016-9}
}
Turek RS, Roper RG and Brosnahan JW (1998), "Further direct comparisons of incoherent scatter and medium frequency radar winds from AIDA '89", Journal of Atmospheric and Terrestrial Physics. Vol. 60, pp. 337-347.
BibTeX:
@article{Turek1998,
  author = {Turek, R. S. and Roper, R. G. and Brosnahan, J. W.},
  title = {Further direct comparisons of incoherent scatter and medium frequency radar winds from AIDA '89},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1998},
  volume = {60},
  pages = {337-347},
  doi = {10.1016/S1364-6826(97)00089-8}
}
Zhou Q (1998), "Two-day oscillation of electron concentration in thelower ionosphere", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 60(17), pp. 1669-1677.
BibTeX:
@article{Zhou1998,
  author = {Q.H. Zhou},
  title = {Two-day oscillation of electron concentration in thelower ionosphere},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {1998},
  volume = {60},
  number = {17},
  pages = {1669-1677},
  doi = {10.1016/S1364-6826(98)00100-X}
}
Zhou QH, Perillat P, Cho JYN and Mathews JD (1998), "Simultaneous meteor echo observations by large-aperture VHF and UHF radars", Radio Science. Vol. 33(6), pp. 1641-1654.
BibTeX:
@article{Zhou1998a,
  author = {Zhou, Q. H. and Perillat, P. and Cho, J. Y. N. and Mathews, J. D.},
  title = {Simultaneous meteor echo observations by large-aperture VHF and UHF radars},
  journal = {Radio Science},
  year = {1998},
  volume = {33},
  number = {6},
  pages = {1641-1654},
  doi = {10.1029/98RS02430}
}
Aponte N, Woodman RF, Swartz WE and Farley DT (1997), "Measuring ionospheric densities, temperatures, and drift velocities simultaneously at Jicamarca", Geophysical Research Letters. Vol. 24(22), pp. 2941-2944.
Abstract: Incoherent scatter autocorrelation function measurements are difficult to make in the F region at Jicamarca because of very strong clutter contamination by coherent echoes from unstable plasma waves in the E-region electrojet that are aligned with the magnetic field. We have developed a more effective way to deal with this clutter that improves the quality of the temperature (and composition when light ions are present) data. Other coherent echoes (much weaker than electrojet echoes but stronger than incoherent scatter) are also received through the antenna sidelobes from field-aligned irregularities in the 140–170 km altitude range during daytime. These latter echoes have a very narrow bandwidth, and so it is easy to measure their Doppler shift and obtain the vertical plasma drift velocity, which is proportional to the zonal electric field.
BibTeX:
@article{Aponte1997,
  author = {Aponte, Nestor and Woodman, Ronald F. and Swartz, Wesley E. and Farley, Donald T.},
  title = {Measuring ionospheric densities, temperatures, and drift velocities simultaneously at Jicamarca},
  journal = {Geophysical Research Letters},
  year = {1997},
  volume = {24},
  number = {22},
  pages = {2941-2944},
  url = {http://dx.doi.org/10.1029/97GL02898},
  doi = {10.1029/97GL02898}
}
Bailey G, Balan N and Su Y (1997), "The Sheffield University plasmasphere ionosphere model-a review", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 59(13), pp. 1541-1552.
Abstract: A brief description of the Sheffield University plasmasphere ionosphere model (SUPIM) is presented. In the model, time-dependent equations of continuity, momentum, and energy balance are solved along eccentric-dipole magnetic field lines for the densities, field-aligned fluxes and temperatures of the O+, H+, He+, N2+, O2+and NO+ ions, and the electrons. A review of some of the important results from recent studies of the model is presented. The studies show that during daytime, the equatorial plasma fountain can rise to altitudes of around 800 km at the magnetic equator and can cover magnetic latitudes of about ± 30 °. At regions outside the fountain, plasma flows towards the magnetic equator from both hemispheres and leads to the formation of an additional layer, the F3 layer, at latitudes close to the magnetic equator (± 10 °). The peak electron density of the F3 layer can exceed that of the F2 layer for a short period of time near noon when the ExB drift is large. Associated with the enhanced electron densities of the F3 layer are reduced electron temperatures. The modelled electron temperatures and densities are in accord with observations made by the Hinotori satellite at 600 km altitude. Closer agreement in the modelled and observed values is achieved if the phase and magnitude of the meridional wind, as given by the HWM90 thermospheric wind model, are modified in accordance with the observations made by the Japanese MU radar and the AE-E satellite. There is better agreement in the modelled and observed values when the equatorial vertical ExB drift velocity model used by SUPIM has an altitude variation in accord with the observations made by the AE-E satellite and at Arecibo.
BibTeX:
@article{Bailey1997,
  author = {G.J. Bailey and N. Balan and Y.Z. Su},
  title = {The Sheffield University plasmasphere ionosphere model-a review},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {1997},
  volume = {59},
  number = {13},
  pages = {1541-1552},
  url = {http://dx.doi.org/10.1016/S1364-6826(96)00155-1},
  doi = {10.1016/S1364-6826(96)00155-1}
}
Bauske R, Noel S and Prolss GW (1997), "Ionospheric storm effects in the nighttime E region caused by neutralized ring current particles", Annales Geophysicae. Vol. 15, pp. 300-305.
BibTeX:
@article{Bauske1997,
  author = {Bauske, R and Noel, S and Prolss, G W},
  title = {Ionospheric storm effects in the nighttime E region caused by neutralized ring current particles},
  journal = {Annales Geophysicae},
  year = {1997},
  volume = {15},
  pages = {300-305},
  doi = {10.1007/s00585-997-0300-2}
}
Cho JYN and Rottger J (1997), "An updated review of polar mesosphere summer echoes: Observation, theory, and their relationship to noctilucent clouds and subvisible aerosols", Journal of Geophysical Research: Atmospheres. Vol. 102(D2), pp. 2001-2020.
Abstract: Peculiar atmospheric radar echoes from the high-latitude summer mesosphere have spurred much research in recent years. The radar data (taken on frequency bands ranging from 2 to 1290 MHz) have been supplemented by measurements from an increasing arsenal of in situ (rocket borne) and remote sensing (satellites and lidars) instruments. Theories to explain these polar mesosphere summer echoes (PMSEs) have also proliferated. Although each theory is distinct and fundamentally different, they all share the feature of being dependent on the existence of electrically charged aerosols. It is therefore natural to assume that PMSEs are intimately linked to the other fascinating phenomenon of the cold summer mesopause, noctilucent clouds (NLCs), which are simply ice aerosols that are large enough to be seen by the naked eye. In this paper we critically examine both the data collected and the theories proposed, with a special focus on the relationship between PMSEs and NLCs.
BibTeX:
@article{Cho1997,
  author = {Cho, John Y. N. and Rottger, Jurgen},
  title = {An updated review of polar mesosphere summer echoes: Observation, theory, and their relationship to noctilucent clouds and subvisible aerosols},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1997},
  volume = {102},
  number = {D2},
  pages = {2001-2020},
  url = {http://dx.doi.org/10.1029/96JD02030},
  doi = {10.1029/96JD02030}
}
Deng W, Salah JE, Clark RR, Franke SJ, Fritts DC, Hoffmann P, Kuerschner D, Manson AH, Meek CE, Murphy D, Nakamura T, Palo SE, Riggin DM, Roble RG, Schminder R, Singer W, Tsuda T, Vincent RA and Zhou Q (1997), "Coordinated global radar observations of tidal and planetary waves in the mesosphere and lower thermosphere during January 20–30, 1993", Journal of Geophysical Research: Space Physics. Vol. 102(A4), pp. 7307-7318.
Abstract: A multi-instrument global campaign involving incoherent scatter, medium frequency, and meteor wind radars was conducted during the period of January 20–30, 1993, to study the dynamics of the mesosphere and lower thermosphere. Data obtained from 15 radar stations covering a wide latitude range have been used to determine the global distribution of planetary and tidal waves during this 10-day campaign. Spectral analysis of the neutral winds measured by the radars in the altitude range from 80 to 130 km indicates the existence of a strong 48-hour wave near 90 km at latitudes between 40°N and 40°S that is present up to 108 km at 18°N. The semidiurnal tide is large at middle and high latitudes near 90 km and is predominant above 110 km, while the diurnal tide is observed to be particularly important in the upper mesosphere near 40° latitude. A least squares fit to the radar data is performed to obtain the amplitudes and phases of the tidal and 48-hour waves. Comparison with National Center for Atmospheric Research thermosphere-ionosphere-mesosphere general circulation model shows that the predictions from the model agree reasonably well with the observed global morphology of tidal wave amplitudes.
BibTeX:
@article{Deng1997,
  author = {Deng, W. and Salah, J. E. and Clark, R. R. and Franke, S. J. and Fritts, D. C. and Hoffmann, P. and Kuerschner, D. and Manson, A. H. and Meek, C. E. and Murphy, D. and Nakamura, T. and Palo, S. E. and Riggin, D. M. and Roble, R. G. and Schminder, R. and Singer, W. and Tsuda, T. and Vincent, R. A. and Zhou, Q.},
  title = {Coordinated global radar observations of tidal and planetary waves in the mesosphere and lower thermosphere during January 20–30, 1993},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A4},
  pages = {7307-7318},
  url = {http://dx.doi.org/10.1029/96JA01630},
  doi = {10.1029/96JA01630}
}
Djuth FT, Sulzer MP, Elder JH and Wickwar VB (1997), "High-resolution studies of atmosphere-ionosphere coupling at Arecibo Observatory, Puerto Rico", Radio Science. Vol. 32(6), pp. 2321-2344.
Abstract: Very accurate measurements of electron density can be made at Arecibo Observatory, Puerto Rico, by applying the coded long-pulse (CLP) radar technique [Sulzer, 1986a] to plasma line echoes from daytime photoelectrons [Djuth et al., 1994]. In the lower thermosphere above Arecibo, background neutral waves couple to the ionospheric plasma, typically yielding ?1–3% electron density “imprints” of the waves. These imprints are present in all observations made to date; they are decisively detected at 30–60 standard deviations above the “noise level” imposed by the measurement technique. Complementary analysis and modeling efforts provide strong evidence that these fluctuations are caused by internal gravity waves. Properties of the neutral waves such as their period and vertical wavelength are closely mirrored by the electron density fluctuations. Frequency spectra of the fluctuations exhibit a high-frequency cutoff consistent with calculated values of the Brunt-VÄisÄlÄ frequency. Vertical half wavelengths are typically in the range 2–25 km between 115- and 160-km altitude, and the corresponding phase velocities are always directed downward. Some waves have vertical wavelengths short enough to be quenched by kinematic viscosity. In general, the observed electron density imprints are relatively “clean” in that their vertical wavelength spectrum is characteristically narrow-banded. It is estimated that perturbations in the horizontal wind field as small as 2–4 m/s can give rise to the observed electron density fluctuations. However, the required wind speed can be significantly greater depending on the orientation of the neutral wave's horizontal wave vector relative to the geomagnetic field. Limited observations with extended altitude coverage indicate that wave imprints can be detected at thermospheric heights as high as 500 km.
BibTeX:
@article{Djuth1997,
  author = {Djuth, F. T. and Sulzer, M. P. and Elder, J. H. and Wickwar, V. B.},
  title = {High-resolution studies of atmosphere-ionosphere coupling at Arecibo Observatory, Puerto Rico},
  journal = {Radio Science},
  year = {1997},
  volume = {32},
  number = {6},
  pages = {2321-2344},
  url = {http://dx.doi.org/10.1029/97RS02797},
  doi = {10.1029/97RS02797}
}
Fesen CG, Emery BA, Buonsanto MJ, Zhou QH and Sulzer MP (1997), "Simulations of the F region during the January 1993 10-day campaign", Journal of Geophysical Research: Space Physics. Vol. 102(A4), pp. 7249-7265.
Abstract: The 10-day World Day campaign during January 20–30, 1993, provided an opportunity to test the current capability of the National Center for Atmospheric Research general circulation models and to conduct simple numerical experiments to investigate possible causes of day-to-day variability. Detailed data sets from the Arecibo and Millstone Hill incoherent scatter radars provided information on the middle- and low-latitude thermosphere and ionosphere during low solar activity which can be compared with model predictions. The theoretical model was used to examine the impact of varying two of the model inputs: the high-latitude energy and momentum sources and the semidiurnal tidal waves from the lower atmosphere. These exercises indicated that varying the high latitude inputs affect the simulations even to relatively low latitudes. The neutral winds in the models were responsive to the level of auroral activity and also to the magnitude of the waves from the lower atmosphere, particularly the neutral zonal winds. The simulated hmax were only affected at night by varying the model inputs. Use of the assimilative mapping of ionospheric electrodynamics (AMIE) technique is necessary to produce realistic quiet-time zonal ion drifts at low latitudes following local sunset. The ion and neutral temperatures proved nearly insensitive to the specifications of the auroral or the tidal inputs, particularly the temperatures at Arecibo. This is in contrast to the observations in which temperatures may vary by up to 100 K from day to day with more pronounced variability at night. In the models, only a large geomagnetic disturbance produced a perturbation in the temperatures but with magnitudes significantly smaller than those observed. The discrepancies may indicate an underestimate of the high-latitude Joule heating due to small-scale variability in magnetospheric electric fields, which would affect the neutral circulation and composition, and inadequate representation of the F region dynamo and conjugate effects in the models.
BibTeX:
@article{Fesen1997,
  author = {Fesen, C. G. and Emery, B. A. and Buonsanto, M. J. and Zhou, Q. H. and Sulzer, M. P.},
  title = {Simulations of the F region during the January 1993 10-day campaign},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A4},
  pages = {7249-7265},
  url = {http://dx.doi.org/10.1029/96JA03312},
  doi = {10.1029/96JA03312}
}
Goldman M, Newman D, Drake R and Afeyan BB (1997), "Theory of convective saturation of Langmuir waves during ionospheric modification of a barium cloud", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 59(18), pp. 2335-2350.
Abstract: In recent experiments (Djuth, F. T., Sulzer, M. P., Elder, J. H. and Groves, K. M. (1995) Journal of Geophysical Research, 100, 17,347), a parametric decay instability was excited by an ordinarywave HF pump during an ionospheric chemical release from a rocket over Arecibo, PR, which created an artificial ‘barium ionosphere,’ with peak plasma frequency above the pump frequency, and a density gradient with a (short) 5 km scale length. Simultaneous incoherent scattering measurements revealed a strong initial asymmetry in the amplitudes of almost vertically upgoing versus downgoing measured plasma waves. We can account for this asymmetry in terms of linear convective saturation of parametrically unstable plasma waves propagating over a range of altitudes along geometric optics ray paths. Qualitative features of the frequency spectrum of the measured downgoing wave are in agreement with this model, although the theoretically predicted spectrum is narrower than observed. The observed altitude localization of the enhanced spectrum to a few range cells is consistent with the theory.
BibTeX:
@article{Goldman1997,
  author = {M.V. Goldman and D.L. Newman and R.Paul Drake and Bedros B. Afeyan},
  title = {Theory of convective saturation of Langmuir waves during ionospheric modification of a barium cloud},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1997},
  volume = {59},
  number = {18},
  pages = {2335-2350},
  url = {http://dx.doi.org/10.1016/S1364-6826(96)00127-7},
  doi = {10.1016/S1364-6826(96)00127-7}
}
Hickey MP, Walterscheid RL, Taylor MJ, Ward W, Schubert G, Zhou Q, Garcia F, Kelly MC and Shepherd GG (1997), "Numerical simulations of gravity waves imaged over Arecibo during the 10-day January 1993 campaign", Journal of Geophysical Research. Vol. 102(A6), pp. 11475-11490.
Abstract: Recently, measurements were made of mesospheric gravity waves in the OI (5577 å) nightglow observed from Arecibo, Puerto Rico, during January 1993 as part of a special 10-day campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of two waves through the mesopause region and calculated the O(1S) nightglow response to the waves. Mean winds derived from both UARS wind imaging interferometer (WINDII) and Arecibo incoherent scatter radar observations were employed in the computations as were the climatological zonal winds defined by COSPAR International Reference Atmosphere 1990 (CIRA). For both sets of measured winds the observed waves encounter critical levels within the O(1S) emission layer, and wave amplitudes, derived from the requirement that the simulated and observed amplitudes of the O(1S) fluctuations be equal, are too large for the waves to be gravitationally stable below the emission layer. Some of the model coefficients were adjusted in order to improve the agreement with the measurements, including the eddy diffusion coefficients and the height of the atomic oxygen layer. The effect of changing the chemical kinetic parameters was investigated but was found to be unimportant. Eddy diffusion coefficients that are 10 to 100 times larger than presently accepted values are required to explain most of the observations in the cases that include the measured background winds, whereas the observations can be modeled using the nominal eddy diffusion coefficients and the CIRA climatological winds. Lowering the height of the atomic oxygen layer improved the simulations slightly for one of the simulated waves but caused a less favorable simulation for the other wave. For one of the waves propagating through the WINDII winds the simulated amplitude was too large below 82 km for the wave to be gravitationally stable, in spite of the adjustments made to the model parameters. This study demonstrates that an accurate description of the mean winds is an essential requirement for a complete interpretation of observed wave-driven airglow fluctuations.
BibTeX:
@article{Hickey1997,
  author = {Hickey, M P and Walterscheid, R L and Taylor, M J and Ward, W and Schubert, G. and Zhou, Q and Garcia, F and Kelly, M C and Shepherd, G G},
  title = {Numerical simulations of gravity waves imaged over Arecibo during the 10-day January 1993 campaign},
  journal = {Journal of Geophysical Research},
  year = {1997},
  volume = {102},
  number = {A6},
  pages = {11475-11490},
  url = {http://dx.doi.org/10.1029/97JA00181},
  doi = {10.1029/97JA00181}
}
Kelley MC and Miller CA (1997), "Electrodynamics of midlatitude spread F 3. Electrohydrodynamic waves? A new look at the role of electric fields in thermospheric wave dynamics", Journal of Geophysical Research: Space Physics. Vol. 102(A6), pp. 11539-11547.
Abstract: The study of atmospheric tides has long recognized the importance of electrodynamic or ohmic losses, in the form of JxB forces, on the strength of winds in the Earth's upper atmosphere. Now, recent observations of ionospheric and atmospheric phenomena (particularly, but not exclusively, at midlatitudes) are suggesting that electrodynamic processes may also be important for atmospheric buoyancy waves with periods as short as a few hours. During the daytime, passive ohmic losses may be responsible for a strong azimuthal filtering of buoyancy waves which limits their propagation in the upper atmosphere to near equatorward where there is a minimum of the JxB drag. At night, the active development of plasma instabilities, whose growth rate is also strongly azimuthally dependent, may not only minimize ion drag but may also feed energy into particular buoyancy waves to counteract the nighttime's enhanced molecular and thermal dissipation, thus creating a strong equatorward and westward orientation to observed traveling ionospheric disturbances. In all, the strength of the apparent coupling between buoyancy waves and ionospheric electrodynamics in the upper atmosphere may suggest the classification and study of a new form of electrohydrodynamic waves.
BibTeX:
@article{Kelley1997,
  author = {Kelley, Michael C. and Miller, Clark A.},
  title = {Electrodynamics of midlatitude spread F 3. Electrohydrodynamic waves? A new look at the role of electric fields in thermospheric wave dynamics},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A6},
  pages = {11539-11547},
  url = {http://dx.doi.org/10.1029/96JA03841},
  doi = {10.1029/96JA03841}
}
Lee MC, Riddolls RJ, Vilece KD, Dalrymple NE, Rowlands MJ, Moriarty DT, Groves KM, Sulzer MP and Kuo SP (1997), "Laboratory reproduction of Arecibo experimental results: HF wave-enhanced Langmuir waves", Geophysical Research Letters. Vol. 24(2), pp. 115-118.
Abstract: Laboratory experiments at MIT using the Versatile Toroidal Facility (VTF) have produced “cascading” and “frequency-upshifted” spectra of HF wave-enhanced Langmuir waves resembling the spectra observed in Arecibo experiments. The VTF experiments are well-explained using the source mechanism proposed by Kuo and Lee [1992] to interpret observed Langmuir wave spectra at Arecibo, Puerto Rico. This mechanism is referred to as a nonlinear scattering of parametric decay instability (PDI)-excited Langmuir waves by “pre-existing” lower hybrid waves to preferentially produce anti-Stokes (i.e., frequency-upshifted) Langmuir waves. Recent radar spectral observations of anti-Stokes Langmuir waves at Arecibo with improved range and time resolution [Sulzer and Fejer, 1994] can be reasonably understood in terms of this mechanism.
BibTeX:
@article{Lee1997,
  author = {Lee, M. C. and Riddolls, R. J. and Vilece, K. D. and Dalrymple, N. E. and Rowlands, M. J. and Moriarty, D. T. and Groves, K. M. and Sulzer, M. P. and Kuo, S. P.},
  title = {Laboratory reproduction of Arecibo experimental results: HF wave-enhanced Langmuir waves},
  journal = {Geophysical Research Letters},
  year = {1997},
  volume = {24},
  number = {2},
  pages = {115-118},
  url = {http://dx.doi.org/10.1029/96GL03886},
  doi = {10.1029/96GL03886}
}
Mahajan KK, Sethi NK and Pandey V (1997), "The diurnal variation of E-F valley parameters from incoherent scatter measurements at Arecibo", Advances in Space Research. Vol. 20, pp. 1781-1784.
Abstract: The size and shape of the valley region between E and F layers is studied for nighttime conditions by using high resolution electron density profiles measured by the incoherent scatter radar at Arecibo, Puerto Rico, (18.3°N,66.7°W). Important valley parameters like width, depth and height of the valley minimum are derived from these measurements. By combining these nighttime results with our earlier daytime model (Mahajan, et.al, 1994), we now present a model for the full diurnal variation of the E–F valley parameters. Comparison with IRI-90 indicates significant differences between our model and the IRI valley model.
BibTeX:
@article{Mahajan1997,
  author = {Mahajan, K K and Sethi, N K and Pandey, V},
  title = {The diurnal variation of E-F valley parameters from incoherent scatter measurements at Arecibo},
  journal = {Advances in Space Research},
  year = {1997},
  volume = {20},
  pages = {1781-1784},
  url = {http://dx.doi.org/10.1016/S0273-1177(97)00591-7},
  doi = {10.1016/S0273-1177(97)00591-7}
}
Mathews J, Meisel D, Hunter K, Getman V and Zhou Q (1997), "Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar", Icarus . Vol. 126(1), pp. 157 - 169.
Abstract: We present measured and inferred properties of a possible new class of “sporadic” micrometeors discovered during 18 January 1995 observations made using the very sensitive 430 MHz radar system located at Arecibo Observatory in Puerto Rico. Over 200 of these objects were observed in a 2-hr period near sunrise. The average speed was about 55 km/sec in a range of 45-63 km/sec. Approximately two-thirds of the observed trajectories were apparently nearly parallel with the vertical beam and occurred on the 93-102 km height interval. The observed occurrence rate of these meteor returns combined with the size the Arecibo beam points to a meteor flux corresponding-in the “classical” view-to 15th magnitude micrometeors. This information along with observed deceleration rates and radar scattering cross-sections of order 10-8m2, leads us to conclude that the majority of the meteors observed appear to be of order 1 ug in mass. The depth of atmospheric penetration and inferred perihelia, the majority of which lie mostly within the orbits of Mercury and Venus, point to compositions of dense refractory material. Retrograde orbits that lie well out of the plane of the ecliptic combined with the modeled effects of radiation pressure induced orbit decay suggest that these particles-with no obvious parent body-originated in the outer reaches of the solar system and that they may even be primordial in origin. It is suggested that most if not all of these particles are associated with the North Apex “source” of sporadic meteors reported by Jones and Brown (1993,Mon. Not. R. Astron. Soc.265, 524–532). Additionally, several possible radar scattering mechanisms are discussed, none of which seem completely satisfactory.
BibTeX:
@article{Mathews1997157,
  author = {J.D. Mathews and D.D. Meisel and K.P. Hunter and V.S. Getman and Q. Zhou},
  title = {Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar},
  journal = {Icarus },
  year = {1997},
  volume = {126},
  number = {1},
  pages = {157 - 169},
  url = {http://www.sciencedirect.com/science/article/pii/S0019103596956419},
  doi = {10.1006/icar.1996.5641}
}
Mathews JD, Sulzer MP and Perillat P (1997), "Aspects of layer electrodynamics inferred from high-resolution ISR observations of the 80–270 km ionosphere", Geophysical Research Letters. Vol. 24(11), pp. 1411-1414.
Abstract: The Arecibo 430 MHz Incoherent Scatter Radar (ISR) has been used to observe vertical ionospheric electron concentration profiles in the 80–280 km altitude region at the highest sustained resolutions (150 m, 10 s) thus far reported for “ion-line” measurements. We present results that reveal layers and wave-like features in unprecedented detail and likely point to electrodynamic processes linking the E and F regions. Tidal Ion Layers (TILs) and sporadic E (Es) layers in the 100–110 km altitude region often display significant peaks and edges that appear in only one range gate (150 m). Also, previously unreported wave-like plasma structures—termed “ion rain”—with ~12 minutes apparent period, normalized amplitudes of 1–3%, and vertical wavelengths in excess of 30 km have been observed extending from base of the F-layer to the evening intermediate TIL with indications of coupling into the 90–110 km region below.
BibTeX:
@article{Mathews1997a,
  author = {Mathews, John D. and Sulzer, Michael P. and Perillat, Phil},
  title = {Aspects of layer electrodynamics inferred from high-resolution ISR observations of the 80–270 km ionosphere},
  journal = {Geophysical Research Letters},
  year = {1997},
  volume = {24},
  number = {11},
  pages = {1411-1414},
  url = {http://dx.doi.org/10.1029/97GL01320},
  doi = {10.1029/97GL01320}
}
Mendillo M, Baumgardner J, Nottingham D, Aarons J, Reinisch B, Scali J and Kelley M (1997), "Investigations of thermospheric-ionospheric dynamics with 6300-å images from the Arecibo Observatory", Journal of Geophysical Research: Space Physics. Vol. 102(A4), pp. 7331-7343.
Abstract: Pilot observations were conducted at Arecibo, Puerto Rico, using an all-sky, image-intensified CCD camera system in conjunction with radar, ionosonde, and Global Positioning System (GPS) diagnostic systems during the periods January 19–28, 1993, and February 21 to August 22, 1995. These represent the first use of campaign mode operations of an imager at Arecibo for extended periods of F region observations. The January 1993 period (the so-called “10-day run”) yielded a rich data set of gravity wave signatures, perhaps the first case of direct imaging of thermospheric wave train properties in the F region. The 6-month 1995 campaign revealed two additional optical signatures of F region dynamics. A brightness wave in 6300 å passing rapidly through the field of view (FOV) has been linked to meridional winds driven by the midnight temperature maximum (MTM) pressure bulge. On May 3, 1995, during a period of geomagnetic activity, a 6300-å airglow depletion pattern entered the Arecibo FOV. Such effects represent the optical signatures of equatorial spread F instabilities that rise above the equator to heights near 2500 km, thereby affecting Arecibo's L = 1.4 flux tube.
BibTeX:
@article{Mendillo1997,
  author = {Mendillo, Michael and Baumgardner, Jeffrey and Nottingham, Daniel and Aarons, Jules and Reinisch, Bodo and Scali, James and Kelley, Michael},
  title = {Investigations of thermospheric-ionospheric dynamics with 6300-å images from the Arecibo Observatory},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A4},
  pages = {7331-7343},
  url = {http://dx.doi.org/10.1029/96JA02786},
  doi = {10.1029/96JA02786}
}
Miller CA and Kelley MC (1997), "Horizontal plasma flow at midlatitudes: More mechanisms and the interpretation of observations", Journal of Geophysical Research: Space Physics. Vol. 102(A6), pp. 11549-11555.
Abstract: The midlatitude ionosphere has been known for decades to exhibit correlated (or anticorrelated, depending on the coordinate system) perpendicular and parallel meridional ion velocities. This correlation is indicative of horizontal plasma flow, despite the highly magnetized character of the midlatitude F region. This coupling of the perpendicular and parallel dynamics is a consequence of extremely weak atmosphere-ionosphere coupling and the strong tendency for the neutral atmosphere to flow horizontally. Three physical mechanisms have previously been identified as effecting this coupling: ion drag, the F region dynamo, and enhanced gravity-driven diffusion. We point out some difficulties with one of these processes and present two additional mechanisms, wind-driven ionospheric equilibrium and gravity wave seeding of plasma instabilities, which can also result in horizontal plasma flow. Although these additional mechanisms further complicate the observational distinction between the possible mechanisms, we argue that an appropriately clustered array of instruments can still distinguish which mechanism is responsible for any particular geophysical occurrence.
BibTeX:
@article{Miller1997,
  author = {Miller, Clark A. and Kelley, Michael C.},
  title = {Horizontal plasma flow at midlatitudes: More mechanisms and the interpretation of observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A6},
  pages = {11549-11555},
  url = {http://dx.doi.org/10.1029/96JA03842},
  doi = {10.1029/96JA03842}
}
Miller CA, Swartz WE, Kelley MC, Mendillo M, Nottingham D, Scali J and Reinisch B (1997), "Electrodynamics of midlatitude spread F: 1. Observations of unstable, gravity wave-induced ionospheric electric fields at tropical latitudes", Journal of Geophysical Research: Space Physics. Vol. 102(A6), pp. 11521-11532.
Abstract: In part 1 of our series exploring the role of electrical forces in midlatitude spread F, we present observations of an electrodynamically driven traveling ionospheric disturbance which passed over Arecibo Observatory between 22 and 24 AST on January 26, 1993. The total electric potential differences driving the wave were of the order of 1 kV. Our analysis indicates that this disturbance is the result of a midlatitude F region plasma instability seeded by a thermospheric gravity wave. Two novel measurements, in addition to typical incoherent scatter observations, were crucial to this determination: the use of 6300 å airglow images from the coupling, energetics, and dynamics of atmospheric regions (CEDAR) allsky imager to track the two-dimensional, mesoseale dynamics of the disturbance and the use of a portable ionosonde to simultaneously measure the fieldline integrated ionospheric conductivity in the conjugate hemisphere. We have also determined that this disturbance, like several previously observed midlatitude disturbances, is consistent with our theoretical knowledge of the basic instability of the midlatitude ionosphere described originally by Perkins [1973].
BibTeX:
@article{Miller1997a,
  author = {Miller, C. A. and Swartz, W. E. and Kelley, M. C. and Mendillo, M. and Nottingham, D. and Scali, J. and Reinisch, B.},
  title = {Electrodynamics of midlatitude spread F: 1. Observations of unstable, gravity wave-induced ionospheric electric fields at tropical latitudes},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A6},
  pages = {11521-11532},
  url = {http://dx.doi.org/10.1029/96JA03839},
  doi = {10.1029/96JA03839}
}
Miller CA (1997), "Electrodynamics of midlatitude spread F 2. A new theory of gravity wave electric fields", Journal of Geophysical Research: Space Physics. Vol. 102(A6), pp. 11533-11538.
Abstract: In this paper, we investigate the response of the nighttime, midlatitude ionosphere to atmospheric gravity waves in the presence of the global dynamo electric field. Previous theories of gravity wave-ionosphere interaction have neglected the zero-order electric field generated by the global dynamo. We find, however, that gravity wave winds carrying the ionosphere upward and downward along the tilted midlatitude magnetic field can cause spatial variations in the total conductive load experienced by the global circuit. In turn, these variations in ionospheric conductivity create divergences in the global current which produce local electric fields. Since ionospheric conductivity depends on altitude, any nighttime gravity wave which perturbs the height of the ionosphere may, through this mechanism, produce such fields. If true, the consequences of this interaction are potentially quite important. Gravity wave-induced electric fields may be the source of much of the day-to-day variation of the total ionospheric electric field; they may substantially alter the ionospheric electron density response to gravity waves; and they may seed ionospheric plasma instabilities. Further experimental investigations are necessary to test these predictions.
BibTeX:
@article{Miller1997b,
  author = {Miller, Clark A.},
  title = {Electrodynamics of midlatitude spread F 2. A new theory of gravity wave electric fields},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A6},
  pages = {11533-11538},
  url = {http://dx.doi.org/10.1029/96JA03840},
  doi = {10.1029/96JA03840}
}
Nossal S, Roesler FL, Coakley MM and Reynolds RJ (1997), "Geocoronal hydrogen Balmer-alpha line profiles obtained using Fabry-Perot annular summing spectroscopy: Effective temperature results", Journal of Geophysical Research: Space Physics. Vol. 102(A7), pp. 14541-14553.
BibTeX:
@article{Nossal1997,
  author = {Nossal, S. and Roesler, F. L. and Coakley, M. M. and Reynolds, R. J.},
  title = {Geocoronal hydrogen Balmer-alpha line profiles obtained using Fabry-Perot annular summing spectroscopy: Effective temperature results},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A7},
  pages = {14541-14553},
  doi = {10.1029/97JA00293}
}
Palmer RD, Larsen MF, Howell PB, Cho JYN, Narayanan RM and Kelley MC (1997), "A new spatial interferometry capability using the Arecibo 430-MHz radar", Radio Science. Vol. 32(2), pp. 749-755.
Abstract: This note describes the new spatial interferometry (SI) capability of the 430-MHz radar system of the Arecibo Observatory (AO). Three limitations exist when the 430-MHz radar is used for observations in the tropospheric and stratospheric regions. First, the AO radar currently has a lower height limitation of approximately 6 km because of the existing transmit/receive switch. Second, fading ground clutter limits the useful data which can be obtained and complicates the analysis. Third, the large mass of the feed system, which slows down beam steering, reduces the temporal resolution of any measurements requiring multiple beam positions. For these reasons, an SI system has been developed which will be shown to reduce these limitations. A brief description of the hardware is provided, and preliminary data are presented.
BibTeX:
@article{Palmer1997,
  author = {Palmer, Robert D. and Larsen, Miguel F. and Howell, Perry B. and Cho, John Y. N. and Narayanan, Ram M. and Kelley, Michael C.},
  title = {A new spatial interferometry capability using the Arecibo 430-MHz radar},
  journal = {Radio Science},
  year = {1997},
  volume = {32},
  number = {2},
  pages = {749-755},
  url = {http://dx.doi.org/10.1029/96RS03500},
  doi = {10.1029/96RS03500}
}
Palo SE, Hagan ME, Meek CE, Vincent RA, Burrage MD, McLandress C, Franke SJ, Ward WE, Clark RR, Hoffmann P, Johnson R, Kürschner D, Manson AH, Murphy D, Nakamura T, Portnyagin YI, Salah JE, Schminder R, Singer W, Tsuda T, Virdi TS and Zhou Q (1997), "An Intercomparison Between the CSWMn UARS and Ground Based Radar Observations: A Case study in January 1993", Annales Geophysicae. Vol. 15(9), pp. 1123-1141.
BibTeX:
@article{Palo1997,
  author = {Palo, S. E. and Hagan, M. E. and Meek, C. E. and Vincent, R. A. and Burrage, M. D. and McLandress, C. and Franke, S. J. and Ward, W. E. and Clark, R. R. and Hoffmann, P. and Johnson, R. and Kürschner, D. and Manson, A. H. and Murphy, D. and Nakamura, T. and Portnyagin, Y. I. and Salah, J. E. and Schminder, R. and Singer, W. and Tsuda, T. and Virdi, T. S. and Zhou, Q.},
  title = {An Intercomparison Between the CSWMn UARS and Ground Based Radar Observations: A Case study in January 1993},
  journal = {Annales Geophysicae},
  year = {1997},
  volume = {15},
  number = {9},
  pages = {1123-1141},
  doi = {10.1007/s00585-997-1123-x}
}
Pandey VK, Sethi NK and Mahajan K (1997), "Topside electron density distribution during sunrise and sunset conditions at Arecibo: comparison with IRI", Advances in Space Research. Vol. 20(9), pp. 1765-1768.
BibTeX:
@article{Pandey1997,
  author = {Pandey, V K and Sethi, N K and Mahajan, K},
  title = {Topside electron density distribution during sunrise and sunset conditions at Arecibo: comparison with IRI},
  journal = {Advances in Space Research},
  year = {1997},
  volume = {20},
  number = {9},
  pages = {1765-1768},
  doi = {10.1016/S0273-1177(97)00587-5}
}
Scali JL, Reinisch BW, Richards PG, Zhou Q, Sulzer M and Swartz WE (1997), "Comparison of incoherent scatter radar and Digisonde measurements with field line interhemispheric plasma modeled results at middle and low latitudes", Journal of Geophysical Research: Space Physics. Vol. 102(A4), pp. 7345-7355.
BibTeX:
@article{Scali1997,
  author = {Scali, J. L. and Reinisch, B. W. and Richards, P. G. and Zhou, Qihou and Sulzer, Mike and Swartz, W. E.},
  title = {Comparison of incoherent scatter radar and Digisonde measurements with field line interhemispheric plasma modeled results at middle and low latitudes},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A4},
  pages = {7345-7355},
  doi = {10.1029/96JA03520}
}
Scali JL, Reinisch BW, Kelley MC, Miller CA, Swartz WE, Zhou QH and Radicella S (1997), "Incoherent scatter radar and Digisonde observations at tropical latitudes, including conjugate point studies", Journal of Geophysical Research: Space Physics. Vol. 102(A4), pp. 7357-7367.
BibTeX:
@article{Scali1997a,
  author = {Scali, J. L. and Reinisch, B. W. and Kelley, M. C. and Miller, C. A. and Swartz, W. E. and Zhou, Q. H. and Radicella, S.},
  title = {Incoherent scatter radar and Digisonde observations at tropical latitudes, including conjugate point studies},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1997},
  volume = {102},
  number = {A4},
  pages = {7357-7367},
  doi = {10.1029/96JA03519}
}
Sridharan R, Chandra H, Das S, Sekar R, Sinha H, Raju D, Narayanan R, Raizada S, Misra R, Raghavarao R, Vyas G, Rao P, Ramarao P, Somayajulu V, Babu V and Danilov A (1997), "Ionization hole campaign—a coordinated rocket and ground-based study at the onset of equatorial spread-F: first results", Journal of Atmospheric and Solar-Terrestrial Physics. Vol. 59(16), pp. 2051 - 2067.
Abstract: A comprehensive multi-technique campaign involving the launch of two high altitude RH-560 rockets was carried out from Sriharikota (SHAR), India, a near-equatorial rocket launching station at the onset of equatorial spread-F, along with a host of ground-based complementary experiments at other locations spread over the country. The main objectives were to obtain the background ionospheric and thermospheric conditions at the onset of equatorial spread-F, and to be able to evaluate the relative importance of the various agencies, the neutral dynamics in particular. Multiple barium cloud releases, in situ plasma diagnostic measurements, along with complementary optical and radio probing experiments were carried out as a part of this campaign. The presence of large scale gradients in the ambient electric fields at ~185 km altitude and also of vertical winds of significant magnitudes at higher altitudes were found. The presence of large scale irregularities in the ion densities at heights above 250 km in a region of negative background density gradient is one of the significant new results. The details of the Ionization hole campaign along with the first results are presented and discussed in the context of the present knowledge of the phenomenon of equatorial spread-F.
BibTeX:
@article{Sridharan1997,
  author = {R. Sridharan and H. Chandra and S.R. Das and R. Sekar and H.S.S. Sinha and D.Pallam Raju and R. Narayanan and Shika Raizada and R.N. Misra and R. Raghavarao and G.D. Vyas and P.B. Rao and P.V.S. Ramarao and V.V. Somayajulu and V.V. Babu and A.D. Danilov},
  title = {Ionization hole campaign—a coordinated rocket and ground-based study at the onset of equatorial spread-F: first results},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
  year = {1997},
  volume = {59},
  number = {16},
  pages = {2051 - 2067},
  url = {http://www.sciencedirect.com/science/article/pii/S136468269700031X},
  doi = {10.1016/S1364-6826(97)00031-X}
}
Tepley CA (1997), "Current developments at Arecibo for research in the atmospheric sciences at low latitudes", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 59(13), pp. 1679-1686.
Abstract: We discuss several recent enhancements to the instrumentation that have taken place at the Arecibo Observatory. These improvements and equipment augmentations strengthen Arecibo's unique position as a facility capable of observing the total atmosphere and ionosphere in the tropics. The changes made, or those planned, affected both the radar and the optical systems. We begin with a description of the current status of the Gregorian Upgrade Project and describe the recent additions of supplementary instrumentation. We also note several examples of the latest experimental investigations of the atmosphere, conducted by visiting scientists and local staff, which range from very high altitudes to near the ground.
BibTeX:
@article{Tepley1997,
  author = {Craig A. Tepley},
  title = {Current developments at Arecibo for research in the atmospheric sciences at low latitudes},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1997},
  volume = {59},
  number = {13},
  pages = {1679-1686},
  doi = {10.1016/S1364-6826(96)00167-8}
}
Zhou Q and Kelley M (1997), "Meteor observations by the Arecibo 430 MHz incoherent scatter radar. II. Results from time-resolved observations", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 59(7), pp. 739-752.
BibTeX:
@article{Zhou1997,
  author = {Zhou, QH and Kelley, MC},
  title = {Meteor observations by the Arecibo 430 MHz incoherent scatter radar. II. Results from time-resolved observations},
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1997},
  volume = {59},
  number = {7},
  pages = {739-752},
  doi = {10.1016/S1364-6826(96)00103-4}
}
Zhou QH and Sulzer MP (1997), "Incoherent scatter radar observations of the F-region ionosphere at Arecibo during January 1993 ", Journal of Atmospheric and Solar-Terrestrial Physics . Vol. 59(17), pp. 2213 - 2229.
Abstract: We report incoherent scatter radar observation of the F-region ion drift, plasma density, and electron and ion temperatures during the January 1993 World Day 10-day campaign. Although the observed ion drift during the geomagnetically quiet period agrees with previous observation in the horizontal direction to a large extent for similar geophysical conditions, the vertical ion drift shows a very large downward component throughout the entire day, which averages at about 20m s?1 near the F-region peak. Such a large average downward plasma drift has not been reported before at low latitudes. The downward motion of the F-region plasma comes mainly from the component along the geomagnetic field line, which is chiefly controlled by the meridional wind during the day and ambipolar diffusion during the night. The E â B drift also contributes to the downward motion of the F-region plasma during the nighttime although it is in anti-correlation with the variation introduced by the ion motion along the field line. During the geomagnetically disturbed period on 25 January, the ion drifts showed large departure from the quiet period. The perturbed eastward ion drift was highly correlated with that along the magnetic field, which may be indicative of the presence of field-aligned current. Our observation shows that the daytime electron concentration and electron temperature have contrasting correlations at different altitude ranges in the F-region. They are positively correlated below 180 km, anti-correlated between 220–400 km, not well correlated between 440–620 km, and again positively correlated at 660 km. While the positive correlation at 220–400 km has been observed previously and is well understood, the positive correlations below 180 km and at 660 km are less known and have not been systematically studied. Using the electron energy balance equation, we show that the contrasting relationships between electron concentration and electron temperature depend on the ion composition at lower altitudes; and on how electron heating via photoionization compares with thermal conduction at higher altitudes. Our observation shows that plasma motion, electron concentration and the thermal characteristics of the F-region ionosphere are all interrelated. We also present the day-to-day variability of plasma drift, electron and ion temperatures as well as electron concentration.
BibTeX:
@article{Zhou19972213,
  author = {Qihou H. Zhou and Michael P. Sulzer},
  title = {Incoherent scatter radar observations of the F-region ionosphere at Arecibo during January 1993 },
  journal = {Journal of Atmospheric and Solar-Terrestrial Physics },
  year = {1997},
  volume = {59},
  number = {17},
  pages = {2213 - 2229},
  url = {http://www.sciencedirect.com/science/article/pii/S1364682697000400},
  doi = {10.1016/S1364-6826(97)00040-0}
}
Fukao S, Takami T and Oliver WL (1996), "The Coupled Ionosphere and Thermosphere at Mid-Latitudes in the Asian Sector and Its Comparison with Other Locations", Journal of geomagnetism and geoelectricity. Vol. 48(1), pp. 113-124.
Abstract: The present paper reviews dynamical features of the mid-latitude ionosphere and thermosphere in the Asian sector as quantified by the MU radar at Shigaraki, Japan (35°N, 136°E) and compares these with dynamics reported for other locations. The thermospheric wind and temperature in the Asian sector differ from the wind and temperature measured at other mid-latitude locations. Furthermore, the perpendicular plasma drifts have strong resemblances to those predicted by current models, but their seasonal trends suggest a strong conjugate effect that has not been fully incorporated into our expectations of local behavior. These results provide additional evidence that global features cannot be described by a simple zonal mean. Finally, two features related to gravity waves are discussed. Gravity waves seem to be ubiquitous in the thermosphere and play an important role in creating a variety of electron density fluctuations and irregularities in the mid-latitude ionosphere. Tracking the progression of ionospheric gravity-wave effects between MU radar beams has allowed gravity wave packets to be identified and their dispersion relation to be determined. The character of ionospheric irregularities observed are consistent with their seeding by the Perkins mechanism.
BibTeX:
@article{1996113,
  author = {Shoichiro Fukao and Tomoyuki Takami and William L. Oliver},
  title = {The Coupled Ionosphere and Thermosphere at Mid-Latitudes in the Asian Sector and Its Comparison with Other Locations},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1996},
  volume = {48},
  number = {1},
  pages = {113-124},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/48/1/48_1_113/_article},
  doi = {10.5636/jgg.48.113}
}
Cho JYN, Jurgens RF and Slade MA (1996), "High-resolution stratospheric dynamics measurements with the NASA/JPL Goldstone Solar System Radar", Geophysical Research Letters. Vol. 23(15), pp. 1909-1912.
Abstract: We have used, for the first time that we are aware of, the NASA/JPL Goldstone planetary radar to study the Earth's atmosphere. With its high bandwidth and power, we were able to achieve a height resolution of 20 m, which is significantly better than the usual 150-m resolution for stratospheric radars. Here we discuss the observation of a very thin scattering layer that persisted over several hours at the same height just above the tropopause. We question the assumption of turbulent radar scatter based on the available evidence, and also investigate the two-minute oscillation observed in the vertical velocity.
BibTeX:
@article{Cho1996,
  author = {Cho, John Y. N. and Jurgens, Raymond F. and Slade, Martin A.},
  title = {High-resolution stratospheric dynamics measurements with the NASA/JPL Goldstone Solar System Radar},
  journal = {Geophysical Research Letters},
  year = {1996},
  volume = {23},
  number = {15},
  pages = {1909-1912},
  url = {http://dx.doi.org/10.1029/96GL01570},
  doi = {10.1029/96GL01570}
}
Cho JY, Alcala CM, Kelley MC and Swartz WE (1996), "Further effects of charged aerosols on summer mesospheric radar scatter", Journal of Atmospheric and Terrestrial Physics . Vol. 58(6), pp. 661 - 672.
Abstract: In an earlier paper, we showed that charged aerosols play a crucial role in enhancing radar echoes from the summer polar mesosphere through reduced diffusion turbulent scatter and dressed aerosol scatter (Cho et al., 1992a). Here, we explore the effects of charged aerosols on radar scatter through ‘fossil’ turbulence and electron density depletion layers. We find that the former can produce radar scatter even after the decay of neutral gas turbulence, while the latter, which are probably produced by the scavenging of free electrons by ice particles, are a candidate for causing partial reflection or Fresnel scatter. Furthermore, we examine the mutual aerosol interaction restriction on dressed aerosol scatter more closely. We find that a high ambient electron density and low aerosol number density are needed for effective dressed aerosol scatter to occur. We then show that very small (less than 1 nm radii), negatively charged aerosols enhance electron diffusivity, and thus inhibit radar scatter. Also, ice aerosol sedimentation, in the light of the reduced diffusion theory, leads us to conclude that the statistical peak in Polar Mesospheric Summer Echoes (PMSE) power should be located between the mean mesopause and the average noctilucent cloud (NLC) height, which agrees with observations. Finally, we invoke time lags in the ice particle formation cycle to account for the observed non-correlation between PMSE and NLC occurrence.
BibTeX:
@article{Cho1996a,
  author = {John Y.N. Cho and Christian M. Alcala and Michael C. Kelley and Wesley E. Swartz},
  title = {Further effects of charged aerosols on summer mesospheric radar scatter},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1996},
  volume = {58},
  number = {6},
  pages = {661 - 672},
  url = {http://www.sciencedirect.com/science/article/pii/0021916995000658},
  doi = {10.1016/0021-9169(95)00065-8}
}
Coakley M. M.; Roesler FLRRJNS (1996), "Fabry-Perot CCD annular-summing spectroscopy: study and implementation for aeronomy applications", Applied Optics. Vol. 35, pp. 6479-6493. Optical Society of America.
Abstract: The technique of Fabry-Perot CCD annular-summing spectroscopy, with particular emphasis on applications in aeronomy, is discussed. Parameter choices for optimizing performance by the use of a standard format CCD array are detailed. Spectral calibration methods, techniques for determining the ring pattern center, and effects imposed by limited radial resolution caused by superpixel size, variable by on-chip binning, are demonstrated. The technique is carefully evaluated experimentally relative to the conventional scanning Fabry-Perot that uses a photomultiplier detector. We evaluate three extreme examples typical of aeronomical spectroscopy using calculated signal-to-noise ratios. Predicted sensitivity gains of 10–30 are typical. Of the cases considered, the largest savings in integration time are estimated for the day sky thermospheric O1D case, in which the bright sky background dominates the CCD read noise. For profile measurements of faint night sky emission lines, such as exospheric hydrogen Balmer-&alpha; , long integration times are required to achieve useful signal-to-noise ratios. In such cases, CCD read noise is largely overcome. Predictions of a factor of 10-15 savings in integration time for night sky Balmer-&alpha; observations are supported by field tests. Bright, isolated night sky lines such as thermospheric O1D require shorter integration times, and more modest gains dependent on signal level are predicted. For such cases it appears from estimate results that the Fabry–Perot CCD annular-summing technique with a conventional rectangular format may be outperformed by a factor of 2-5 by special CCD formats or by unusual optical coupling configurations that reduce the importance of read noise, based on the ideal transmission for any additional optics used in these configurations.
BibTeX:
@article{Coakley1996,
  author = {Coakley, M. M.; Roesler, F. L.; Reynolds, R. J.; Nossal, S.},
  title = {Fabry-Perot CCD annular-summing spectroscopy: study and implementation for aeronomy applications},
  journal = {Applied Optics},
  publisher = {Optical Society of America},
  year = {1996},
  volume = {35},
  pages = {6479-6493},
  url = {http://dx.doi.org/10.1364/AO.35.006479},
  doi = {10.1364/AO.35.006479}
}
Flaherty JP, Kelley MC, Seyler CE and Fitzgerald TJ (1996), "Simultaneous VHF and transequatorial HF observations in the presence of bottomside equatorial spread F", Journal of Geophysical Research: Space Physics. Vol. 101(A12), pp. 26811-26818.
Abstract: Simultaneous transequatorial HF and VHF incoherent scatter measurements were conducted in Peru in January 1994. On the evening of January 13, conditions as measured at VHF by the Jicamarca Radio Observatory were comparatively mild. The spread F observed on this evening was confined to the bottomside of the F layer and relatively weak. Yet dramatic propagation effects were seen in the HF. Strong off great circle signals with more than 10 Hz in Doppler spread were measured. Large spreads in angle of arrival, as much as 20 deg, were also seen. The strength of the off great circle returns are comparable to the strength of signals arriving from the direction of the great circle and are believed to result from total reflections from horizontal gradients in the ionosphere. Jicamarca VHF measurements substantiate this hypothesis. We present data from a single evening during which two separate events occurred. From the combined VHF and HF measurements, we conclude that the source of the off great circle reflections consists of a longitudinal density gradient which is immediately followed by a region of unstable plasma. The unstable plasma affecting the HF signals is shown to consist of a sequence of finger-like structures having a nominal separation of 15 km which remain below the height of maximum F region electron density.
BibTeX:
@article{Flaherty1996,
  author = {Flaherty, J. P. and Kelley, M. C. and Seyler, C. E. and Fitzgerald, T. J.},
  title = {Simultaneous VHF and transequatorial HF observations in the presence of bottomside equatorial spread F},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1996},
  volume = {101},
  number = {A12},
  pages = {26811-26818},
  url = {http://dx.doi.org/10.1029/96JA01115},
  doi = {10.1029/96JA01115}
}
Gonzalez SA and Sulzer MP (1996), "Detection of He+ layering in the topside ionosphere over Arecibo during equinox solar minimum conditions", Geophysical Research Letters. Vol. 23(18), pp. 2509-2512.
Abstract: We describe recent developments in and results from topside incoherent scatter radar (ISR) measurements at Arecibo, PR, emphasizing helium ion measurements. Recent improvements in the data taking modes and the data processing permit isolation of the concentrations of oxygen, helium and hydrogen ions between the F region peak and 2000 km with about 10 minute time resolution. The need for the three ion non-linear least squares fits is justified by use of the goodness of fit; a two ion fit is shown to be unacceptable. The new measurements are optimized for the rapid height variations in the solar minimum nighttime ionosphere by replacing the traditional 1 ms pulse with a 500 µs pulse. We show results from one day of a five day experiment during the Spring of 1994. For these equinox solar minimum conditions, the altitude distribution of the helium ions usually has a maximum near the O+ to H+ transition altitude (ht), forming a distinct layer, most noticeable during the night. The maximum helium ion concentrations tend to be quite low, 2 or 3 â 10¨ cm-3, or 10-20% of the topside plasma at the peak of the He+ layer. The transition altitude, ht, varies from about 1200 km to 1400 km during the day to near 500 km at night, and the He+ layer follows this altitude variation. Finally we show that the location of the layer near ht and its intensification during the night can be explained using ambipolar diffusion equations.
BibTeX:
@article{Gonzalez1996,
  author = {Gonzalez,, Sixto A. and Sulzer, Michael P.},
  title = {Detection of He+ layering in the topside ionosphere over Arecibo during equinox solar minimum conditions},
  journal = {Geophysical Research Letters},
  year = {1996},
  volume = {23},
  number = {18},
  pages = {2509-2512},
  url = {http://dx.doi.org/10.1029/96GL02212},
  doi = {10.1029/96GL02212}
}
Gulyaeva T, Mahajan K and Sethi N (1996), "Modification of IRI half-density height option for low latitudes", Advances in Space Research. Vol. 18(6), pp. 149-152.
Abstract: The International Reference Ionosphere provides an option for using the half-density height h0.5 when determining the bottom-side electron density profile. For low latitudes the ratio h0.5/hmF2 (peak height) is modified using Arecibo incoherent scatter electron density profiles. A linear variation with latitude of the coefficients is introduced for nighttime and daytime in case h0.5 is located above the F1 layer heights (class ‘A’). The profile semithickness is large when 0.5NmF2 value is less than NmF1 (class ‘B’). At low latitudes class ‘B’ occurs during the first half of the day; at mid-latitudes, however, the Digisonde data from Millstone Hill show these to occur during most of the daytime.
BibTeX:
@article{Gulyaeva1996,
  author = {T.L. Gulyaeva and K.K. Mahajan and N.K. Sethi},
  title = {Modification of IRI half-density height option for low latitudes},
  journal = {Advances in Space Research},
  year = {1996},
  volume = {18},
  number = {6},
  pages = {149-152},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00916-7},
  doi = {10.1016/0273-1177(95)00916-7}
}
Habbal SR, Mossman A, Gonzalez R and Esser R (1996), "Radio, visible, and X ray emission preceding and following a coronal mass ejection", Journal of Geophysical Research: Space Physics. Vol. 101(A9), pp. 19943-19955.
Abstract: This study uses both disk and limb observations to examine the changing conditions of the low solar corona, below 1.5 Rs, preceding and following a coronal mass ejection observed on the west limb on April 12, 1993. The disk observations comprise 90 cm (333 MHz) radio and daily Yohkoh soft X ray measurements, while the limb observations include measurements of emission from X rays, Fe X 637.4 nm and Fe XIV 530.3 nm coronal lines, and broadband Thomson-scattered white light. The analysis of the disk and limb observations shows that throughout the 3 days of consecutive observations, the occurrence and persistence of nonthermal emission at 90 cm, also known as type I noise storm emission, were associated with large-scale magnetic structures where the coronal mass ejection eventually occurred. Other than a subsequent flare observed in X rays at the limb, the changes in the coronal emission preceding and following the event were not markedly different from changes in other neighboring structures. The analysis of this novel combination of data supports the current view that coronal mass ejections are a cause rather than a consequence of the “classical” solar activity in the low corona. The radio observations, on the other hand, suggest that a connection between a noise storm and a coronal mass ejection exists. However, they do not necessarily imply that the noise storm actually initiates the event.
BibTeX:
@article{Habbal1996,
  author = {Habbal, Shadia R. and Mossman, Amy and Gonzalez, Raymond and Esser, Ruth},
  title = {Radio, visible, and X ray emission preceding and following a coronal mass ejection},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1996},
  volume = {101},
  number = {A9},
  pages = {19943-19955},
  url = {http://dx.doi.org/10.1029/96JA01190},
  doi = {10.1029/96JA01190}
}
Hagen JB and Baumgartner HA (1996), "Backscatter gain of aperture antennas", Radio Science. Vol. 31(4), pp. 693-699.
Abstract: It is well known that the conventional on-axis gain of an aperture-type antenna is maximized when the aperture illumination pattern has uniform amplitude and phase. For backscatter radar measurements, however, the distributed target brings the off-axis gain into play, and the sensitivity is proportional to the square of the gain averaged over the solid angle of the beam. It has been assumed that this backscatter gain, like on-axis gain, is maximized when the illumination is uniform. We show that this is not quite the case; for a fixed aperture area the backscatter gain can be increased at least 6% by using the kind of amplitude taper that reduces sidelobe levels. It is also well known that the maximum on-axis gain is proportional to the area of the aperture but independent of the shape. We show that this is not the case for backscatter gain.
BibTeX:
@article{Hagen1996,
  author = {Hagen, Jon B. and Baumgartner, Hans A.},
  title = {Backscatter gain of aperture antennas},
  journal = {Radio Science},
  year = {1996},
  volume = {31},
  number = {4},
  pages = {693-699},
  url = {http://dx.doi.org/10.1029/96RS01095},
  doi = {10.1029/96RS01095}
}
Howell PB, Palmer R, Narayanan R, Larsen MF and Cho JYN (1996), "Preliminary results from the Arecibo 430 MHz spatial interferometry system", Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.'., In Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International. Vol. 4, pp. 1926-1928.
Abstract: The 430 MHz radar system of the Arecibo Observatory (AO) possesses one of the largest power-aperture products in the world. The aperture is effectively 200-300 m and the peak power is approximately 2.5 MW. Designed originally for ionospheric and radioastronomy, the AO is built into a natural bowl in the Puerto Rican terrain. The feed system is directed downward, toward the dish, and then reflected into the atmosphere. As a result, the platform which houses the feed systems must be very stable. The structure is suspended by a network of steel cables strung from large concrete towers. In total, the feed platform weighs approximately 600 tons and cannot be moved rapidly. This results in an enormous amount of wasted time during the steering of the beam, which can take up to 30 min. Doppler beam swinging (DBS) techniques have been attempted with the system but adequate temporal resolution is difficult to obtain. The DBS technique determines the wind velocity by obtaining the Doppler shift of the scattered signal from several beam directions, which are converted into radial velocity estimates. Subsequently, the radial velocity estimate can be used to derive the overall wind field. DBS techniques have been attempted with the AO system but adequate temporal resolution is difficult to obtain because of the slow beam steering. Multi-receiver techniques, which use only a single beam direction, can alleviate the temporal resolution concern since no beam steering is needed. In a collaborative effort a spatial interferometric (SI) system, i.e., multireceiver, has been built and will be installed at the AO. Preliminary tests have been performed in 1995 with final installation planned for the spring of 1996. The results of the tests are discussed
BibTeX:
@article{Howell1996,
  author = {Howell, P. B. and Palmer, R.D. and Narayanan, R.M. and Larsen, M. F. and Cho, J. Y N},
  title = {Preliminary results from the Arecibo 430 MHz spatial interferometry system},
  booktitle = {Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International},
  journal = {Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.'},
  year = {1996},
  volume = {4},
  pages = {1926-1928},
  url = {http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=516844&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D516844},
  doi = {10.1109/IGARSS.1996.516844}
}
Huang X and Reinisch B (1996), "Vertical electron density profiles from the Digisonde network ", Advances in Space Research . Vol. 18(6), pp. 121-129.
Abstract: The global Digisonde network provides a vast volume of ionogram-derived electron density profile data from some 50 stations. The current true height inversion program NHPC differs significantly from the original algorithms developed for real time calculation on PC 286 machines. NHPC successfully inverts about 90% of the autoscaled ionograms. A stand-alone version of NHPC can invert h'(f) traces from any digital or analog ionogram. For each layer, the N(h) profile is expressed in terms of shifted Chebyshev polynomials with a logarithmic argument containing the starting plasma frequency and the critical frequency of the layer. The peak height and a set of coefficients specify the electron density distribution of each layer. A valley model derived from incoherent scatter observations at Arecibo describes the E-F trasition. The frequent problem of missing h'(f) data points at the beginning of a trace is addressed by analytical expansion in the true height (profile) domain rather than by direct extrapolation of the h'(f) trace. The validity of the Digisonde NHPC profiles has been verified by comparison with incoherent scatter radar profiles.
BibTeX:
@article{Huang1996,
  author = {Xueqin Huang and B.W. Reinisch},
  title = {Vertical electron density profiles from the Digisonde network },
  journal = {Advances in Space Research },
  year = {1996},
  volume = {18},
  number = {6},
  pages = {121-129},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00912-4},
  doi = {10.1016/0273-1177(95)00912-4}
}
Huang C-S and Kelley MC (1996), "Numerical simulations of gravity wave modulation of midlatitude sporadic E layers", Journal of Geophysical Research: Space Physics. Vol. 101(A11), pp. 24533-24543.
Abstract: We have used a computer simulation to study gravity wave modulation of midlatitude sporadic E (Es) layers. It is shown that a horizontally stratified Es layer may be deformed by gravity waves and become a large-scale wavelike structure. Spatial resonance is not required for significant modulations to form. For a southward propagating gravity wave the south side sections of the wavelike deformed Es layer may overturn and appear as field-aligned features stretching about 10 km in altitude. The deformed Es layer drifts at a velocity larger than neutral wind velocity but smaller than the phase velocity of the gravity wave. The scale length of the wavelike Es layers is determined by the horizontal wavelength of the gravity wave. If there are two or more Es layers modulated simultaneously by a gravity wave, the height dependence of the amplitude of the wave must be taken into account. The Es layer at lower altitude is weakly disturbed if the gravity wave has only a small amplitude there. In contrast, the Es layer at higher altitude may be deeply modulated and appear as field aligned, since the amplitude of the gravity wave has increased greatly in comparison with the amplitude at lower altitude. The numerical results may be used to explain the midlatitude E region field-aligned irregularities observed by the Middle and Upper atmospheric (MU) radar.
BibTeX:
@article{Huang1996a,
  author = {Huang, Chao-Song and Kelley, Michael C.},
  title = {Numerical simulations of gravity wave modulation of midlatitude sporadic E layers},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1996},
  volume = {101},
  number = {A11},
  pages = {24533-24543},
  url = {http://dx.doi.org/10.1029/96JA02327},
  doi = {10.1029/96JA02327}
}
Isham B, Hoz CL, Kohl H, Hagfors T, Leyser T and Rietveld M (1996), "Recent EISCAT heating results using chirped ISR", Journal of Atmospheric and Terrestrial Physics. Vol. 58, pp. 369-383.
Abstract: The chirp technique has recently become fully operational on the EISCAT UHF radar system and has been used for daytime observations of the HF-modified ionosphere over Ramfjordmoen in November 1992 and March 1993. During certain periods the UHF observations show a difference in the frequencies of the photoelectron-enhanced plasma line and the HF-enhanced plasma line (HFPL) similar to the one seen during chirp observations of heating at Arecibo. The frequency difference seen at EISCAT, however, varied dramatically with time and howetimes vanished completely, which was not the case at Arecibo. This frequency difference indicates that the HFPL source region is located several kilometres above the height where the linear Langmuir dispersion equation indicates a resonance should occur at the HF pump frequency. Simultaneous long-pulse measurements of the HFPL spectrum show a cascade-type structure in the HFPL spectra which, according to current theories, indicates that the HFPL must follow the Langmuir dispersion relation. This may be interpreted to mean that the HF-induced plasma waves are excited within plasma density depletions whenever the frequency difference is present. UHF observations also sometimes show a feature in the HF-modified plasma line spectrum which appears to be the same as that observed in an experiment performed at EISCAT in August 1986 by Isham et al. (1990). This new feature has been dubbed the “outshifted” line as it appears downshifted (upshifted) from the heating frequency in the downshifted (upshifted) plasma line spectrum. The magnitude of the shift is in the range of 100–300 kHz.
BibTeX:
@article{Isham1996,
  author = {B. Isham and C. La Hoz and H. Kohl and T. Hagfors and T.B. Leyser and M.T. Rietveld},
  title = {Recent EISCAT heating results using chirped ISR},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1996},
  volume = {58},
  pages = {369-383},
  url = {http://www.sciencedirect.com/science/article/pii/0021916995000429},
  doi = {10.1016/0021-9169(95)00042-9}
}
Kildal P-S and Davis M (1996), "Characterisation of near-field focusing with application to low altitude beam focusing of the Arecibo tri-reflector system", IEE Proceedings on Microwaves, Antennas and Propagation. Vol. 143(4), pp. 284-292.
Abstract: Antennas are normally characterised in terms of their far field radiation patterns, directive gain and aperture efficiency. The paper describes how to characterise antennas that are focused in the near field, in terms of a focusing gain and a focusing efficiency. The paper also presents an algorithm from which the location of the near-field focus can be calculated directly from the aperture field of the antenna. The definitions and the algorithm are applied to an extensive numerical study of focusing of the beam of the Arecibo tri-reflector system at low altitudes. The focusing is obtained by displacing the feed, or the tertiary reflector, or both at the same time. Finally, an approximate formula is presented, from which results can be calculated easily at other frequencies and altitudes than those being computed
BibTeX:
@article{Kildal1996,
  author = {Kildal, P- S. and Davis, M.M.},
  title = {Characterisation of near-field focusing with application to low altitude beam focusing of the Arecibo tri-reflector system},
  journal = {IEE Proceedings on Microwaves, Antennas and Propagation},
  year = {1996},
  volume = {143},
  number = {4},
  pages = {284-292},
  url = {http://mr.crossref.org/iPage/?doi=10.1049%2Fip-map%3A19960388},
  doi = {10.1049/ip-map:19960388}
}
Mahajan K (1996), "Contributions of incoherent-scatter radar measurements at Arecibo for the improvement of IRI", Advances in Space Research. Vol. 18, pp. 131-140.
Abstract: In the years 1974 to 1977 the incoherent-scatter radar at Arecibo made high resolution measurements of electron density in time and altitude, under the I29 program. This program ran on monthly basis and each observing run was for about 36 hours, consisting of two daytime periods and the intervening night. Electron density was measured from 100 to 500 km with a single 24 vs pulse which provided an altitude resolution of 3.6 km. These measurements provided very accurate values of hmF2, h0.5, E-F valley parameters and topside Ne gradient thereby providing important inputs for the improvement of IRI. This paper gives a summary of these inputs.
BibTeX:
@article{Mahajan1996,
  author = {Mahajan, K},
  title = {Contributions of incoherent-scatter radar measurements at Arecibo for the improvement of IRI},
  journal = {Advances in Space Research},
  year = {1996},
  volume = {18},
  pages = {131-140},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00913-2},
  doi = {10.1016/0273-1177(95)00913-2}
}
Mathews JD (1996), "The dynamics of ion layer generation in the 80–150 km altitude region at low and mid-latitudes", Journal of Atmospheric and Terrestrial Physics . Vol. 58(6), pp. 673 - 682.
Abstract: The association of sporadic ion and sporadic sodium layers in the low-latitude, 90–100 km altitude region suggests that we must look beyond the windshear theory for details of the formation mechanism of sporadic layers in the 80–150 km altitude region. We present evidence, including specific 85–105 km results from the AIDA-89 and the ALOHA-90 campaigns, that 80–150 km altitude sporadic layers—including sporadic sodium layers—are generated in a complex interplay of tidal and acoustic-gravity wave (AGW) dynamics with temperature-dependent chemistry where wave-produced temperature variations are both adiabatic and dissipative or turbulent (non-reversible) in origin. We suggest that layering processes are best studied with an instrument cluster that includes sodium and iron lidars, MST radar (turbulence), incoherent scatter radar (electron concentration and winds), meteor radar techniques (winds), passive optical/IR imaging techniques, and appropriate rocket payloads to study a significant volume of the 80–150 km altitude region. We introduce the concept of volumtric radar and lidar techniques.
BibTeX:
@article{Mathews1996,
  author = {John D. Mathews},
  title = {The dynamics of ion layer generation in the 80–150 km altitude region at low and mid-latitudes},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1996},
  volume = {58},
  number = {6},
  pages = {673 - 682},
  note = {Ionosphere-Middle and Lower Atmosphere Interactions },
  url = {http://www.sciencedirect.com/science/article/pii/0021916995000666},
  doi = {10.1016/0021-9169(95)00066-6}
}
Miller N, Grebowsky J, Hoegy W and Mahajan K (1996), "A comparison of ionization densities determined from spacecraft and incoherent scatter radar data", Journal of Atmospheric and Terrestrial Physics . Vol. 58(15), pp. 1735 - 1740.
Abstract: By comparing direct measurements taken from onboard Atmosphere Explorer spacecraft (AE), in eccentric orbit, with incoherent scatter radar (ISR) measurements taken from the ground, we illustrate both the merits and the difficulties involved in such comparisons. Five altitude profiles of ionization determined from AE, in near coincidence with ground stations making ISR measurements, compared favorably with the ISR data so long as the Æ measurements were properly analyzed for the effects of variations in latitude and solar zenith angle along the spacecraft orbit.
BibTeX:
@article{Miller1996,
  author = {N.J. Miller and J.M. Grebowsky and W.R. Hoegy and K.K. Mahajan},
  title = {A comparison of ionization densities determined from spacecraft and incoherent scatter radar data},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1996},
  volume = {58},
  number = {15},
  pages = {1735 - 1740},
  url = {http://www.sciencedirect.com/science/article/pii/0021916995002006},
  doi = {10.1016/0021-9169(95)00200-6}
}
Mitra A (1996), "Feasible groundbased atmospheric and flux measurements by developing countries in support of satellite data", Advances in Space Research . Vol. 17(8), pp. 17-26.
Abstract: To allow increasing participation of developing countries in global change studies, ground based measurement systems which can be easily comissioned and provide support to satellite observations so as to fit into global mapping need to be chosen carefully. Those relating to atmospheric parameters (greenhouse gas concentrations, emission fluxes, transport properties, etc.) are discussed here. The simplest and of most immediate interest relate to sources and sinks of CH4 (primarily from rice paddy fields, animals, wetlands) and N2O (soils, oceans). Measurement techniques and inter-country campaign plans are discussed. There are also important possibilities of using the same technique for measurements of emissions from biomass burning alongwith ozone measurements coupled with survey of biomass burning areas from satellites. Another major area concerns the proposed ITYO programme (International Troposheric Ozone Year), for which, apart from balloon ozone ascents, use of UV-B radiometry at selected wavelengths is considered. The third area discussed concerns measurements of atmospheric aerosols using Multi-wavelength Radiometer (MWR). In addition, in the last few years, a number of advanced groundlevel systems have been installed at low latitudes, which, if made available widely to developing country scientists, and their participation supported financially, could provide a major opportunity for world class research. These include: the MST radar at Tirupati (India) Chung-Li (Taiwan) and Arecibo, Puerto Rico; the Lidars at Thumba and at Natal, Brazil; and the Laser Heterodyning System and mm-wave radiospectrometer at Delhi.
BibTeX:
@article{Mitra1996,
  author = {A.P. Mitra},
  title = {Feasible groundbased atmospheric and flux measurements by developing countries in support of satellite data},
  journal = {Advances in Space Research },
  year = {1996},
  volume = {17},
  number = {8},
  pages = {17-26},
  url = {http://www.sciencedirect.com/science/article/pii/027311779500655X},
  doi = {10.1016/0273-1177(95)00655-X}
}
Pandey VK, Sethi NK and Mahajan KK (1996), "Comparison of IRI topside electron density profile with Arecibo incoherent scatter measurements", Advances in Space Research. Vol. 18(6), pp. 289-292.
Abstract: Midday and Midnight topside electron density profiles measured with the incoherent scatter radar at Arecibo (magn.dip 50°) are compared with the IRI-90. It is found that, in general, IRI overestimates electron densities. Similar results have earlier been reported from Millstone Hill (magn.dip 72°).
BibTeX:
@article{Pandey1996,
  author = {Pandey, V K and Sethi, N K and Mahajan, K K},
  title = {Comparison of IRI topside electron density profile with Arecibo incoherent scatter measurements},
  journal = {Advances in Space Research},
  year = {1996},
  volume = {18},
  number = {6},
  pages = {289-292},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00938-8},
  doi = {10.1016/0273-1177(95)00938-8}
}
Pandey VK and Sethi NK (1996), "Comparison of hmF2 and midday bottomside electron density profile obtained from IRI and incoherent scatter measurements", Advances in Space Research. Vol. 18(6), pp. 33-37.
Abstract: About 2000 electron density height profiles observed with the Arecibo (magn.dip 50°) incoherent scatter radar are used to compare the diurnal and seasonal variations of hmF2 with the IRI-90. A good agreement is seen for the median values. The midday bottomside profiles normalized to the peak density are compared with IRI-90 for each season and it is found that IRI overestimates the electron density distribution in the region 100 km below the F2 peak for equinox and summer but matches well during winter.
BibTeX:
@article{Pandey1996a,
  author = {Pandey, V K and Sethi, N K},
  title = {Comparison of hmF2 and midday bottomside electron density profile obtained from IRI and incoherent scatter measurements},
  journal = {Advances in Space Research},
  year = {1996},
  volume = {18},
  number = {6},
  pages = {33-37},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00895-0},
  doi = {10.1016/0273-1177(95)00895-0}
}
Sethi N, Goel M and Pandey V (1996), "Deriving main LAY parameters from Incoherent Scatter measurements and their comparisons with IRI-90", Advances in Space Research. Vol. 18(6), pp. 141-144.
Abstract: Using high resolution electron density (Ne) profiles from Incoherent Scatter (I.S.) measurements at Arecibo, geometric parameters (transition height, scale height) of 4 LAY functions are determined. The median values of the above parameters are obtained for each hour during different seasons and compared with main LAY parameters obtained from IRI-90. It is observed that during all the seasons the transition height parameter of the F2 layer derived from observed profiles agrees well with the parameter obtained from IRI during daytime only, while for nighttime large departures are observed for all seasons. Large seasonal variability is also found in the principal scale parameter related to thickness of F2 layer. The difference between those in observed profiles compared to IRI varies from 38 km to 45 km.
BibTeX:
@article{Sethi1996,
  author = {N.K. Sethi and M.K. Goel and V.K. Pandey},
  title = {Deriving main LAY parameters from Incoherent Scatter measurements and their comparisons with IRI-90},
  journal = {Advances in Space Research},
  year = {1996},
  volume = {18},
  number = {6},
  pages = {141-144},
  url = {http://dx.doi.org/10.1016/0273-1177(95)00914-0},
  doi = {10.1016/0273-1177(95)00914-0}
}
Sulzer MP and Gonzalez SA (1996), "Simultaneous measurements of O+ and H+ temperatures in the topside ionosphere over Arecibo", Geophysical Research Letters. Vol. 23(22), pp. 3235-3238.
Abstract: We have measured both proton (TH+) and oxygen ion (TO+) temperatures simultaneously from spectra obtained in the lower topside ionosphere using the Arecibo incoherent scatter radar (ISR). This is the first time that two ion temperatures and three ion compositions have been measured from the same IS spectrum, and, as far as we know, one of the first measurements of both ion temperatures in the ionosphere.First we describe our spectral-domain analysis technique, emphasizing the ability to determine goodness of fit, which allows of the need for and effect of including a parameter to be numerically evaluated. We then show that common TH+ and TO+ allow insufficient freedom, and that separate temperatures are sufficient.A small negative bias in [He+] parameter is removed when the second temperature is allowed to be free while the H+ fraction is not significantly affected. We also show that the measurement cannot be made at altitudes where little O+ is present. The difference between TH+ and TO+ is zero (or at least very small) during the night, and rises to several hundred degrees at about 500 km shortly after sunrise. During the middle of the day the temperature difference declines (presumably due to higher densities) and then rises again before sunset.
BibTeX:
@article{Sulzer1996,
  author = {Sulzer, Michael P. and Gonzalez, Sixto A.},
  title = {Simultaneous measurements of O+ and H+ temperatures in the topside ionosphere over Arecibo},
  journal = {Geophysical Research Letters},
  year = {1996},
  volume = {23},
  number = {22},
  pages = {3235-3238},
  url = {http://dx.doi.org/10.1029/96GL02926},
  doi = {10.1029/96GL02926}
}
Rottger J and Tsuda T (1995), "Studies of the Polar Middle and Lower Atmosphere by an MST Radar on Svalbard", Journal of geomagnetism and geoelectricity. Vol. 47(9), pp. 929-942.
Abstract: This paper describes scientific subjects important in the middle atmosphere in the polar region, considering the effects of phenomena unique to the high latitudes as well as the coupling processes between the neutral and ionized atmosphere. We are particularly pointing out the relevant application of an MST (mesosphere-stratosphere-troposphere) radar for observations of middle and lower atmospheric structure and dynamics. We briefly summarize fundamental techniques of the MST radar. Then, we survey phenomena that are exclusively detected in the polar atmosphere, such as precipitation of high energy particles, aurora) electrojet, stratospheric sudden warming, the polar vortex or a polar night-jet, PSC (polar stratospheric cloud) associated with ozone depletion and PMSE (polar summer mesospheric echoes), related to NLC (noctilucent clouds). Among these phenomena there are certain topics that need to be studied with an MST radar in addition to the multitude of other complementary experiments which are already applied for these studies in the Arctic and Antarctic. Finally, we discuss a realization of an MST radar operated on 50 MHz, which should be established in conjunction with the Svalbard incoherent scatter radar operated on 500 MHz.
BibTeX:
@article{1995929,
  author = {Jurgen Rottger and Toshitaka Tsuda},
  title = {Studies of the Polar Middle and Lower Atmosphere by an MST Radar on Svalbard},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1995},
  volume = {47},
  number = {9},
  pages = {929-942},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/47/9/47_9_929/_article},
  doi = {10.5636/jgg.47.929}
}
Bernhardt PA, Ganguli G, Kelley MC and Swartz WE (1995), "Enhanced radar backscatter from space shuttle exhaust in the ionosphere", Journal of Geophysical Research: Space Physics. Vol. 100(A12), pp. 23811-23818.
Abstract: Enhancements in the backscatter from the 430-MHz radar at Arecibo were recorded during the Spacelab 2 mission when the space shuttle orbital maneuver system (OMS) engines were fired in the ionosphere. The modifications in the backscatter could have been the result of (1) compression of the electrons to produce higher densities, (2) generation of ion acoustic waves, (3) variations in the electron to ion temperature ratio, (4) enhanced scatter cross section by charging of ice particles in the exhaust, or (5) excitation of dust acoustic waves. Rapid cooling and condensation of the exhaust are important in determining the scattering properties of the modified ionosphere. A dusty plasma is formed when electrons are attached to ice particles in the exhaust plume. The calculated neutral temperature inside the exhaust plume is 120 K. Charge exchange between ambient O+ and the cold exhaust molecules yields low-temperature ion beams that excite weakly damped, ion acoustic waves. The enhanced radar echoes are probably the result of scatter from these waves, but the effects of the dusty plasma may be important. During future experiments, the space shuttle will fire the OMS engines over radars located at Arecibo, Puerto Rico; Jicarmarca, Peru; or Kwajalein, Marshall Islands. Measurements of the spectra from these radars will provide the means to distinguish between the various backscatter processes.
BibTeX:
@article{Bernhardt1995,
  author = {Bernhardt, P. A. and Ganguli, G. and Kelley, M. C. and Swartz, W. E.},
  title = {Enhanced radar backscatter from space shuttle exhaust in the ionosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1995},
  volume = {100},
  number = {A12},
  pages = {23811-23818},
  url = {http://dx.doi.org/10.1029/95JA02836},
  doi = {10.1029/95JA02836}
}
Bernhardt PA, Siefring CL, Rodriguez P, Haas DG, Baumback MM, Romero HA, Solin DA, Djuth FT, Duncan LM, Hunton DE, Pollock CJ, Sulzer MP, Tepley CA, Wagner LS and Goldstein JA (1995), "The Ionospheric Focused Heating experiment", Journal of Geophysical Research. Vol. 100, pp. 17331-17346.
Abstract: The Ionospheric Focused Heating rocket was launched on May 30, 1992. The sounding rocket carried an instrument and chemical payload along a trajectory that crossed the intersection of the beams from the 430-MHz incoherent scatter radar and the 5.1-MHz high-power radio wave facility near Arecibo. The release of 30 kg of CF3Br into the F region at 285 km altitude produced an ionospheric hole that acted like a convergent lens to focus the HF transmissions. The power density inside the radio beam was raised by 12 dB immediately after the release. A wide range of new processes were recorded by in situ and ground-based instruments. Measurements by instruments flying through the modified ionosphere show small-scale microcavities (<1 m) and downshifted electron plasma (Langmuir) waves inside the artificial cavity, electron density spikes at the edge of the cavity, and Langmuir waves coincident with ion gyroradius (4 m) cavities near the radio wave reflection altitude. The Arecibo incoherent scatter radar showed 20 dB or greater enhancements in ion acoustic and Langmuir wave turbulence after the 5.1-MHz radio beam was focused by the artificial lens. Enhancements in airglow from chemical reactions and, possibly, electron acceleration were recorded with optical instruments. The Ionospheric Focused Heating experiment verified some of the preflight predictions and demonstrated the value of active experiments that combine high-power radio waves with chemical releases.
BibTeX:
@article{Bernhardt1995a,
  author = {Bernhardt, P A and Siefring, C L and Rodriguez, P and Haas, D G and Baumback, M M and Romero, H A and Solin, D A and Djuth, F T and Duncan, L M and Hunton, D E and Pollock, C J and Sulzer, M P and Tepley, C A and Wagner, L S and Goldstein, J A},
  title = {The Ionospheric Focused Heating experiment},
  journal = {Journal of Geophysical Research},
  year = {1995},
  volume = {100},
  pages = {17331-17346},
  url = {http://dx.doi.org/10.1029/94JA01887},
  doi = {10.1029/94JA01887}
}
Buonsanto M and Holt J (1995), "Measurements of gradients in ionospheric parameters with a new nine-position experiment at Millstone Hill", Journal of Atmospheric and Terrestrial Physics . Vol. 57(6), pp. 705-717.
Abstract: A new nine-position experiment is now routinely carried out with the Millstone Hill incoherent scatter radars which allows estimation of spatial gradients in the measured ionospheric scalar parameters Ne, Te, and Ti, and in the components of the ion velocity vector vi. Use of this technique results in improved estimates of basic and derived parameters from incoherent scatter data at times of significant gradients. We detail the data analysis method and present the first results from this new experiment. The gradients in Ne and in the components of vi are used to compute the motion term in the ionospheric F region continuity equation v · (Nv), which is then combined with DN/Dt to estimate the O+ recombination rate betha at night. Meridional neutral winds Umer are computed from the field-aligned ion velocity vpar and a calculation of the O+ diffusion velocity vd, and it is found that horizontal gradients in the ion velocity field at times significantly affect the calculation of the neutral winds.
BibTeX:
@article{Buonsanto1995,
  author = {M.J. Buonsanto and J.M. Holt},
  title = {Measurements of gradients in ionospheric parameters with a new nine-position experiment at Millstone Hill},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1995},
  volume = {57},
  number = {6},
  pages = {705-717},
  url = {http://www.sciencedirect.com/science/article/pii/002191699400047R},
  doi = {10.1016/0021-9169(94)00047-R}
}
Cho JYN and Morley RL (1995), "PMSE dependence on long-period vertical motions", Geophysical Research Letters. Vol. 22(10), pp. 1197-1200.
Abstract: We analyze the temporal relationship between PMSE (polar mesosphere summer echoes) and long-period vertical motions using the Poker Flat, Alaska radar data. The results show that the vertical velocity leads PMSE by 90° to 180° with a possible upward trend in phase with increasing frequency. We show that this is consistent with the current PMSE theories which depend primarily upon the presence of charged ice aerosols for the enhancement of radar scatter.
BibTeX:
@article{Cho1995,
  author = {Cho, John Y. N. and Morley, Rebecca L.},
  title = {PMSE dependence on long-period vertical motions},
  journal = {Geophysical Research Letters},
  year = {1995},
  volume = {22},
  number = {10},
  pages = {1197-1200},
  url = {http://dx.doi.org/10.1029/95GL01010},
  doi = {10.1029/95GL01010}
}
Cho JYN (1995), "Inertio-gravity wave parameter estimation from cross-spectral analysis", Journal of Geophysical Research: Atmospheres. Vol. 100(D9), pp. 18727-18737.
Abstract: We outline a method for extracting inertio-gravity wave parameters using the autospectra and cross spectra of the horizontal perturbation winds. In essence, we define a statistical hodograph for each spectral bin, thus combining the advantages of the rotary spectrum and hodograph methods. Furthermore, we include the effects of the background vertical shear in the parameter estimation equations, a step that had often been omitted in the past. Applying this technique to a long-period data set taken with the Arecibo 430-MHz radar, we explore its usefulness as well as its limitations. Our analysis of this data set also supports the interpretation of horizontal wind-perturbation rotation in the lower stratosphere over Arecibo as inertio-gravity waves rather than mountain waves imbedded within a background vertical shear.
BibTeX:
@article{Cho1995a,
  author = {Cho, John Y. N.},
  title = {Inertio-gravity wave parameter estimation from cross-spectral analysis},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1995},
  volume = {100},
  number = {D9},
  pages = {18727-18737},
  url = {http://dx.doi.org/10.1029/95JD01752},
  doi = {10.1029/95JD01752}
}
Djuth FT, Sulzer MP, Elder JH and Groves KM (1995), "The CRRES AA 2 Release: HF wave-plasma interactions in a dense Ba+ cloud", Journal of Geophysical Research: Space Physics. Vol. 100(A9), pp. 17347-17366.
Abstract: An ionospheric chemical release, designated AA 2, was performed on July 12, 1992, as part of the NASA Combined Release and Radiation Effects Satellite (CRRES) El Coqui rocket campaign. The purpose of the AA 2 experiment was to study the interaction between a powerful radio wave and a high ion mass (Ba+), “collisionless” plasma. Approximately 35 kg of Ba were explosively released near the center of the Arecibo high-frequency (HF) beam at 253 km altitude. This was the largest Ba release of the CRRES experiments; it yielded a distinctive ionospheric layer having a maximum plasma frequency of 11 MHz. At early times (< 1 min after the release) the HF beam produced the strongest Langmuir waves ever detected with the Arecibo 430-MHz radar. Resonantly enhanced Langmuir waves were observed to be excited principally at the upshifted plasma line (i.e., near 430 MHz + ƒHF, where ƒHF is the frequency of the modifying HF wave), and only weakly excited waves were apparent at the downshifted plasma line (430 MHz - ƒHF). The upshifted plasma-line spectrum contained a dominant peak at the “decay line,” that is, at the frequency 430 MHz + ƒHF - &#240;, where &#240; is close to the Ba+ ionacoustic frequency (~2 kHz). Downshifted plasma-line echoes occurred at frequencies near 430 MHz - ƒHF and 430 MHz - ƒHF - 1 kHz and exhibited little or no signal strength at the decay line (430 MHz - ƒHF + &#240;). During an initial period of intense upshifted plasma-line excitation, the power asymmetry between the upshifted and downshifted plasma lines was of the order of 105 at the decay line. The upshifted plasma line was accompanied by strong HF-enhanced ion waves that were present only at the downshifted acoustic sideband. After geomagnetic field-aligned irregularities formed in the plasma the amplitudes of the upshifted and downshifted plasma lines equalized, and each exhibited spectra characteristic of the parametric decay instability. At early times in the Ba+ plasma the symmetry of wave excitation anticipated for a parametric instability in a stationary, homogeneous plasma was absent. The experimental results indicate that the development of the parametric decay instability needs to be reexamined for a smooth plasma having a small (~5 km) vertical scale length. Moreover, ion flow down geomagnetic field lines appears to suppress instabilities responsible for the formation of field-aligned irregularities and may also have an impact on the way parametric instabilities are excited. New theoretical approaches are needed to resolve many of the issues raised by this experiment.
BibTeX:
@article{Djuth1995,
  author = {Djuth, F. T. and Sulzer, M. P. and Elder, J. H. and Groves, K. M.},
  title = {The CRRES AA 2 Release: HF wave-plasma interactions in a dense Ba+ cloud},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1995},
  volume = {100},
  number = {A9},
  pages = {17347-17366},
  url = {http://dx.doi.org/10.1029/94JA02295},
  doi = {10.1029/94JA02295}
}
Kelley MC, Arce TL, Salowey J, Sulzer M, Armstrong WT, Carter M and Duncan L (1995), "Density depletions at the 10-m scale induced by the Arecibo heater", Journal of Geophysical Research. Vol. 100(A9), pp. 17367-17376.
Abstract: In June 1992 a NASA sponsored sounding rocket, was flown through the Arecibo heater beam to study the structure of the heated volume. The rocket carried an instrument payload and traversed the 5.1-MHz reflection height at 268.5 km. Data from the plasma density probe are presented in this paper. The rocket passed through several regions of disturbed plasma both above and below the reflection level. In these regions, over 180 deep filamentary density depletions were detected. Measured perpendicular to the magnetic field, these depletions or filaments have a mean width at half maximum of 7 m which is roughly equal to twice the ion gyroradius (O+) and a mean depletion depth of 6%. The ratio of parallel to perpendicular scale for these structures exceeds 20,000, and the spacing between the filaments is around 15 m. A power spectrum of the rocket data clearly shows the spectral content of the filaments and also reveals peaks at longer wavelengths which we interpret as the spacing between the bunches and between sets of filaments within a given bunch. We believe that previous scintillation and satellite measurements emphasized these longer wavelengths. The power spectrum measured by the rocket instrumentation falls off as k-4 for wavenumber k larger than 0.4/m and remains above the system noise for structure down to 1 m. It is clear that VHF backscatter from these structures can be explained by our data, as can many features of heater-related, field-aligned irregularities found in the literature.
BibTeX:
@article{Kelley1995,
  author = {Kelley, M C and Arce, T L and Salowey, J and Sulzer, M and Armstrong, W T and Carter, M and Duncan, L},
  title = {Density depletions at the 10-m scale induced by the Arecibo heater},
  journal = {Journal of Geophysical Research},
  year = {1995},
  volume = {100},
  number = {A9},
  pages = {17367-17376},
  url = {http://dx.doi.org/10.1029/95JA00063},
  doi = {10.1029/95ja00063}
}
Keskinen MJ, Rowland HL and Bernhardt P (1995), "Ion gyroradius-sized structures and artificial ion conics generated by the Arecibo ionospheric heater", Geophysical Research Letters. Vol. 22(4), pp. 357-360.
Abstract: A model for ionospheric density structures at the O+ ion gyroradius induced by the Arecibo heater during the recent El Coqui campaign has been developed. We find that (1) these density structures can be accounted for by the parametric decay of the high frequency high power Arecibo heater wave into a low frequency wave with frequency at or near the ion cyclotron frequency and high frequency sideband modes (2) the growth rate of this process peaks at scale sizes corresponding to the O+ ion gyroradius (3) computed density fluctuations, using a strong turbulence model, associated with the ion cyclotron modes, in the nonlinear regime, are in the range of 2–12% and (4) anisotropic ion-conic-like heating will result from this process. The results of this model are in good agreement with recent El Coqui observations.
BibTeX:
@article{Keskinen1995,
  author = {Keskinen, M. J. and Rowland, H. L. and Bernhardt, P.},
  title = {Ion gyroradius-sized structures and artificial ion conics generated by the Arecibo ionospheric heater},
  journal = {Geophysical Research Letters},
  year = {1995},
  volume = {22},
  number = {4},
  pages = {357-360},
  url = {http://dx.doi.org/10.1029/94GL03211},
  doi = {10.1029/94GL03211}
}
Kirkwood S, Cho J, Hall C, Hoppe U-P, Murtagh D, Stegman J, Swartz W, van Eyken A, Wannbergt G and Witt G (1995), "A comparison of PMSE and other ground-based observations during the NLC-91 campaign", Journal of Atmospheric and Terrestrial Physics . Vol. 57(1), pp. 35 - 44.
Abstract: During the period July–August 1991, observations were made of Polar Mesospheric Summer Echoes (PMSE) at 46.9 MHz and 224 MHz by the CUPRI and EISCAT radars, respectively, at two sites in northern Scandinavia. Those observations are compared here with observations of noctilucent clouds, energetic particle precipitation and magnetic disturbances. The appearance and morphology of PMSE are found to be closely correlated at the two frequencies and the two sites, 200 km apart. No correlation is found between PMSE and noctilucent clouds or magnetic disturbance. No correlation is found between energetic particle precipitation and the appearance of PMSE at 46.9 MHz for the whole time period. At 224 MHz, there is no evidence for a correlation before the beginning of August and only one event suggesting a possible correlation after the beginning of August. A minimum in occurrence frequency for PMSE is found between 16 and 21 UT (17–22 LST) which may be related to an expected minimum in background wind strength in that time interval.
BibTeX:
@article{Kirkwood1995,
  author = {S. Kirkwood and J. Cho and C.M. Hall and U.-P. Hoppe and D.P. Murtagh and J. Stegman and W.E. Swartz and A.P. van Eyken and G. Wannbergt and G. Witt},
  title = {A comparison of PMSE and other ground-based observations during the NLC-91 campaign},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1995},
  volume = {57},
  number = {1},
  pages = {35 - 44},
  url = {http://www.sciencedirect.com/science/article/pii/0021916993E00325},
  doi = {10.1016/0021-9169(93)E0032-5}
}
Mahajan K, Kohli R, Sethi N and Pandey V (1995), "Variability of the F-region parameter h0.5", Advances in Space Research . Vol. 15(2), pp. 51-60.
Abstract: High resolution electron density profiles, measured with the Arecibo incoherent scatter radar have been used to derive h0.5, the height of the half density point. More than 2400 profiles, for the period August 1974 – May 1977, have been used to study the behaviour of this parameter. Our analysis shows that during the night, h0.5 varies mostly between 200 and 350 km, but during the day the excursion is larger and values lower than 150 km are also seen. These lower values are often coincident with the presence of a layer (F1) between h0.5 and hmF2. We have therefore, divided the daytime data into two classes, class ‘A’ where h0.5 is more than hmF1 and class ‘B’ where h0.5 is less than hmF1. We find that in both the classes, most of the variability in h0.5 is due to the variability in hmF2 and a linear relationship between h0.5 and hmF2 is seen, although the dispersion in class ‘B’ is larger. Within the same class, no difference is seen in the relationship between day and night. We also compare the parameter View the Y0.5/hmF2 source obtained from the Arecibo measurements with that calculated from the IRI-90 model, based upon Gulyaeva's (1987) formula. In class ‘A’ the median values of this parameter vary between 0.15 and 2.0 with no major seasonal differences. The IRI values, however, are significantly larger. On the other hand, class ‘B’ shows larger seasonal differences, particularly between summer and winter, but the discrepancy with the IRI is somewhat smaller.
BibTeX:
@article{Mahajan1995,
  author = {K.K. Mahajan and R. Kohli and N.K. Sethi and V.K. Pandey},
  title = {Variability of the F-region parameter h0.5},
  journal = {Advances in Space Research },
  year = {1995},
  volume = {15},
  number = {2},
  pages = {51-60},
  url = {http://dx.doi.org/10.1016/S0273-1177(99)80023-4},
  doi = {10.1016/S0273-1177(99)80023-4}
}
Meisel DD, Getman VS, Mathews JD, Jacobs S and Roper RO (1995), "Bolide AIDA: Death of an Aubrite Meteoroid ", Icarus . Vol. 116(2), pp. 227 - 254.
Abstract: A bright, slow moving, bolide observed during the 1989 AIDA campaign is shown to have been a very unusual near-Earth meteoroid. Data were obtained with five different instruments and these observations have now been extensively analyzed. Various indicators point to a stony object and spectroscopic observations in the near IR show two Fe I emissions with an excitation temperature of 3100 K. A third feature due to Na I gives an abundance ratio of Na to Fe of 1:1 by number. Ionized calcium (which is often strong in the near UV), manganese, and cobalt appear to have been weak or absent. Based on the spectrum analysis, we conclude that the object was an enstatite meteoroid and the lack of Mn compared with Fe and Na suggests an aubrite composition. The lightcurve, aerodynamic analysis, and video images show the object underwent extensive fragmentation at virtually all points of its trajectory.
BibTeX:
@article{Meisel1995227,
  author = {David D. Meisel and Vladimir S. Getman and John D. Mathews and S.C. Jacobs and Robert O. Roper},
  title = {Bolide AIDA: Death of an Aubrite Meteoroid },
  journal = {Icarus },
  year = {1995},
  volume = {116},
  number = {2},
  pages = {227 - 254},
  url = {http://www.sciencedirect.com/science/article/pii/S0019103585711232},
  doi = {10.1006/icar.1995.1123}
}
Osterman GB, Heelis RA and Bailey GJ (1995), "Effects of zonal winds and metallic ions on the behavior of intermediate layers", Journal of Geophysical Research: Space Physics. Vol. 100(A5), pp. 7829-7838.
BibTeX:
@article{Osterman1995,
  author = {Osterman, G. B. and Heelis, R. A. and Bailey, G. J.},
  title = {Effects of zonal winds and metallic ions on the behavior of intermediate layers},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1995},
  volume = {100},
  number = {A5},
  pages = {7829-7838},
  doi = {10.1029/94JA03241}
}
Taylor MJ and Garcia FJ (1995), "A two-dimensional spectral analysis of short-period gravity waves imaged in the OI(557.7 nm) and near-infrared OH nightglow emissions over Arecibo, Puerto Rico", Geophysical Research Letters. Vol. 22, pp. 2473-2476.
Abstract: In January 1993 an extensive set of radar and optical data was gathered from various key sites around the world during a coordinated “10 Day Run” designed to investigate the coupled dynamic behavior of the upper atmosphere on a large, medium and small scale. As part of this campaign an all-sky CCD imaging system was operated at Arecibo Observatory, Puerto Rico, to help quantify the response of the low latitude mesosphere-thermosphere system to short period (<1 hour) gravity waves. Measurements of the OI(557.7 nm) and near infrared OH nightglow emissions were made in conjunction with photometric and ISR radar soundings and revealed an abundance of small-scale structure in the 80–100 km range. In this letter we apply two-dimensional spectral analysis techniques to aid in the interpretation of a complex set of image data that consisted of two intersecting quasi-monochromatic gravity wave patterns progressing on approximately orthogonal headings. An investigation of the spectral content and temporal evolution of these wave motions at each emission altitude is presented.
BibTeX:
@article{Taylor1995,
  author = {Taylor, M J and Garcia, F J},
  title = {A two-dimensional spectral analysis of short-period gravity waves imaged in the OI(557.7 nm) and near-infrared OH nightglow emissions over Arecibo, Puerto Rico},
  journal = {Geophysical Research Letters},
  year = {1995},
  volume = {22},
  pages = {2473-2476},
  url = {http://dx.doi.org/10.1029/95GL02491},
  doi = {10.1029/95gl02491}
}
Thide B, Djuth FT, Leyser TB and Ierkic HM (1995), "Evolution of Langmuir turbulence and stimulated electromagnetic emissions excited with a 3-mHz pump wave at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 100(A12), pp. 23887-23899.
Abstract: We present the results of a comparative experimental study at Arecibo of the initial temporal development of stimulated electromagnetic emissions (SEE) and HF-enhanced plasma lines (HFPLs) excited in the ionospheric F region by a high-power O mode radio wave at 3.1745 MHz. These results show that the portion of the SEE spectrum which extends from approximately ?30 kHz to +10 kHz in the sidebands around the injected HF wave, and which is usually referred to as the narrow continuum SEE component, exhibits an overshoot behavior very similar to that of the upshifted HFPL of the 430-MHz radar. Over timescales of a few hundred milliseconds, the narrow continuum emission weakens at all frequencies and gradually changes shape to become more structured. At 3.1745 MHz the amplitude of the HFPL is significantly smaller than that observed at higher HF frequencies; after an overshoot period of 300–500 ms, the HFPL often disappears completely.
BibTeX:
@article{Thide1995,
  author = {Thide, B. and Djuth, F. T. and Leyser, T. B. and Ierkic, H. M.},
  title = {Evolution of Langmuir turbulence and stimulated electromagnetic emissions excited with a 3-mHz pump wave at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1995},
  volume = {100},
  number = {A12},
  pages = {23887-23899},
  url = {http://dx.doi.org/10.1029/95JA01631},
  doi = {10.1029/95JA01631}
}
Turek R, Miller K, Roper R and Brosnahan J (1995), "Mesospheric wind studies during AIDA Act '89: morphology and comparison of various techniques", Journal of Atmospheric and Terrestrial Physics . Vol. 57(11), pp. 1321-1343.
BibTeX:
@article{Turek1995,
  author = {R.S. Turek and K.L. Miller and R.G. Roper and J.W. Brosnahan},
  title = {Mesospheric wind studies during AIDA Act '89: morphology and comparison of various techniques},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1995},
  volume = {57},
  number = {11},
  pages = {1321-1343},
  doi = {10.1016/0021-9169(94)00118-8}
}
Zhou Q and Mathews JD (1995), "Generation of sporadic sodium layers via turbulent heating of the atmosphere?", Journal of Atmospheric and Terrestrial Physics. Vol. 57(11), pp. 1309-1319.
Abstract: When a gravity wave breaks down, its energy is dumped in a narrow altitude range initiating an increase in temperature, which may consequently generate sporadic sodium layers (SSL) through temperature sensitive chemistries. In order to estimate the temperature change resulted from gravity wave breakdown, the energy dissipation through viscous process is discussed. We show that SSLs can be successfully siimulated by solving the continuity equation with a temperature dependent production function. The generation of the largest SSL observed at Arecibo is shown to be associated with gravity waves exhibiting very short vertical wavelength. Simultaneous sodium and temperature measurements suggest that the heating mechanism proposed here as a possible explanation to the occurrence of SSLs, if viable, is more applicable to low and middle latitudes than high latitudes.
BibTeX:
@article{Zhou1995,
  author = {Qihou Zhou and John D. Mathews},
  title = {Generation of sporadic sodium layers via turbulent heating of the atmosphere?},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1995},
  volume = {57},
  number = {11},
  pages = {1309-1319},
  url = {http://www.sciencedirect.com/science/article/pii/002191699597298I},
  doi = {10.1016/0021-9169(95)97298-I}
}
Zhou Q, Tepley CA and Sulzer MP (1995), "Meteor observations by the Arecibo 430 MHz incoherent scatter radar-I. Results from time-integrated observations", Journal of Atmospheric and Terrestrial Physics. Vol. 57(4), pp. 421-431.
BibTeX:
@article{Zhou1995a,
  author = {Qihou Zhou and Craig A. Tepley and Michael P. Sulzer},
  title = {Meteor observations by the Arecibo 430 MHz incoherent scatter radar-I. Results from time-integrated observations},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1995},
  volume = {57},
  number = {4},
  pages = {421-431},
  doi = {10.1016/0021-9169(94)E0011-B}
}
Arce TL and Kelley MC (1994), "Density depletions at the scale of the ion gyro radius in the Arecibo Heater volume", Radiophysics and Quantum Electronics. Vol. 37, pp. 410-431. Springer US.
BibTeX:
@article{Arce1994,
  author = {Arce, T L and Kelley, M C},
  title = {Density depletions at the scale of the ion gyro radius in the Arecibo Heater volume},
  journal = {Radiophysics and Quantum Electronics},
  publisher = {Springer US},
  year = {1994},
  volume = {37},
  pages = {410-431},
  url = {http://dx.doi.org/10.1007/BF01045691},
  doi = {10.1007/bf01045691}
}
Djuth FT, Sulzer MP and Elder JH (1994), "Application of the coded long-pulse technique to plasma line studies of the ionosphere", Geophysical Research Letters. Vol. 21(24), pp. 2725-2728.
Abstract: Recently, the coded long-pulse radar technique was tested at Arecibo Observatory, Puerto Rico using photoelectron-enhanced plasma lines in the daytime ionosphere. The technique immediately proved to be a powerful diagnostic tool for studying natural ionospheric phenomena. Our initial observations indicate that extremely accurate measurements of absolute electron density (0.01 to 0.03% error bars) can be achieved with an altitude resolution of 150 m and a temporal resolution of ~2 s. In addition, the technique provides information about electron density structure within a 150-m altitude cell and yields parameters from which the energy spectrum of suprathermal electrons (>= 5 eV) can be deduced. Our earliest measurements are used to illustrate applications of the coded long-pulse technique to several aeronomic/ionospheric areas of current interest. These include studies of neutral wave motions in the lower thermosphere, measurements of ion composition in the F1 region/upper ionosphere, and investigations of electron-gas thermal balance and photoelectron energy loss processes. The technique can be utilized to examine irregularity formation in the F region, probe electron acceleration processes in ionospheric modification experiments, verify the magnetic field dependence of Langmuir wave damping, and more generally test higher order corrections suggested for the Langmuir dispersion relation. It is anticipated that the latter tests will facilitate measurements of ionospheric currents.
BibTeX:
@article{Djuth1994,
  author = {Djuth, Frank T. and Sulzer, Michael P. and Elder, John H.},
  title = {Application of the coded long-pulse technique to plasma line studies of the ionosphere},
  journal = {Geophysical Research Letters},
  year = {1994},
  volume = {21},
  number = {24},
  pages = {2725-2728},
  url = {http://dx.doi.org/10.1029/94GL01699},
  doi = {10.1029/94GL01699}
}
Djuth FT, Stubbe P, Sulzer MP, Kohl H, Rietveld MT and Elder JH (1994), "Altitude characteristics of plasma turbulence excited with the Tromso Superheater", Journal of Geophysical Research: Space Physics. Vol. 99(A1), pp. 333-339.
BibTeX:
@article{Djuth1994a,
  author = {Djuth, F. T. and Stubbe, P. and Sulzer, M. P. and Kohl, H. and Rietveld, M. T. and Elder, J. H.},
  title = {Altitude characteristics of plasma turbulence excited with the Tromso Superheater},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1994},
  volume = {99},
  number = {A1},
  pages = {333-339},
  doi = {10.1029/93JA02289}
}
Hoppe U-P, Blix T, Thrane E, Lubken F-J, Cho J and Swartz W (1994), "Studies of polar mesosphere summer echoes by VHF radar and rocket probes", Advances in Space Research . Vol. 14(9), pp. 139-148.
BibTeX:
@article{Hoppe1994,
  author = {U.-P. Hoppe and T.A. Blix and E.V. Thrane and F.-J. Lubken and J.Y.N. Cho and W.E. Swartz},
  title = {Studies of polar mesosphere summer echoes by VHF radar and rocket probes},
  journal = {Advances in Space Research },
  year = {1994},
  volume = {14},
  number = {9},
  pages = {139-148},
  doi = {10.1016/0273-1177(94)90126-0}
}
Mahajan K, Pandey V, Goel M, Sethi N and Kohli R (1994), "Incoherent-scatter measurements of E-F valley and comparisons with theoretical and empirical models ", Advances in Space Research . Vol. 14(12), pp. 75-78.
BibTeX:
@article{Mahajan1994,
  author = {K.K. Mahajan and V.K. Pandey and M.K. Goel and N.K. Sethi and R. Kohli},
  title = {Incoherent-scatter measurements of E-F valley and comparisons with theoretical and empirical models },
  journal = {Advances in Space Research },
  year = {1994},
  volume = {14},
  number = {12},
  pages = {75-78},
  doi = {10.1016/0273-1177(94)90243-7}
}
Mathews JD and Morton YT (1994), "Radar Measurements of Dynamics and Layering Process in the 80-150 km Region at Arecibo", Advances in Space Research. Vol. 14(9), pp. 153.
BibTeX:
@article{Mathews1994,
  author = {Mathews, J D and Morton, Y T},
  title = {Radar Measurements of Dynamics and Layering Process in the 80-150 km Region at Arecibo},
  journal = {Advances in Space Research},
  year = {1994},
  volume = {14},
  number = {9},
  pages = {153},
  url = {http://www.sciencedirect.com/science/article/pii/0273117794901287},
  doi = {10.1016/0273-1177(94)90128-7}
}
MelÈndez-Alvira DJ, Burnside RG and Walker JCG (1994), "Modeling the Arecibo nighttime F2 layer: 2. Ionospheric gradients", Journal of Geophysical Research: Space Physics. Vol. 99(A12), pp. 23307-23327.
Abstract: The servo model is extended and used to fit horizontal gradients in the F2 layer height and density and to estimate the zonal Pedersen current and its zonal and meridional gradient. Horizontal gradients were measured from the Arecibo Observatory during the following five nights: August 16-17 and 17-18, 1982; and October 4-5, 5-6, and 9-10, 1983. The model gradients are driven by nonzero current gradients, which are applied as needed to fit the measured gradients in the F2 peak. The gradient in the peak height is accurately reproduced; the peak density gradient is calculated self-consistently in the model. The divergence of the Pedersen current can be deduced when the current flows zonally and is found to differ from zero. This is a consequence of zonal divergence of the model zonal current. Expressions are derived for the divergence of the Hall current and for the curl of the current in the presence of ionospheric gradients. The vertical vorticity of the F region current is determined from the radar and optical measurements and the mass spectrometer/incoherent scatter (MSIS) neutral densities. Both neutral and plasma motions generate current vorticity equally as expected from the F region dynamo. The measured velocity gradients produce more current gradients and vorticity than the measured conductance gradients. The measured height gradient in the perpendicular-north plasma drift (?z??N) is the dominant term in the vorticity and drives the two current shears that cause vorticity. Geometrical factors increase (?z??N) by about 13% in the zonal gradient of the meridional current over the meridional gradient of the zonal current. This causes anticorrelation between the former current shear and the vorticity. The two measured shears generally follow each other, have opposing vorticities and large uncertainties. The nighttime current may be irrotational or have constant vorticity. Large current gradients occur in conjunction with observed descents of the F2 peak height. The gradients are interpreted as due to the midnight pressure bulge at low latitudes. Short-period gravity waves of meteorological origin are ruled out as they were not observed and are limited in their ability to reach ionospheric heights. The harmonic analysis used to obtain horizontal wind gradients is largely unaffected by spatially uniform wind accelerations. Therefore the deduced spatial variations in the measured winds are unlikely to be due to temporal variations.
BibTeX:
@article{Melendez-Alvira1994,
  author = {MelÈndez-Alvira, Daniel J. and Burnside, R. G. and Walker, J. C. G.},
  title = {Modeling the Arecibo nighttime F2 layer: 2. Ionospheric gradients},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1994},
  volume = {99},
  number = {A12},
  pages = {23307-23327},
  url = {http://dx.doi.org/10.1029/94JA01812},
  doi = {10.1029/94JA01812}
}
Milikh GM, Freeman MJ and Duncan LM (1994), "First estimates of HF-induced modifications of the D region by the HF Active Auroral Research Program facility", Radio Science. Vol. 29(5), pp. 1355-1362.
Abstract: A one-dimensional, self-consistent computer code was used to predict electron temperature and density changes in the lower ionosphere caused by high power, high frequency (HF) radio wave heating. The code was used to obtain first estimates of ionospheric perturbations due to the proposed HF Active Auroral Research Program (HAARP) heating instrument, which is currently in the early phases of construction. Simulations were conducted using both pulsed and continuous wave (CW) heating modes, under a variety of conditions. Results indicate that electron temperatures will be increased by up to a factor of 15, and electron densities will be changed by up to 50%relative to natural levels.
BibTeX:
@article{Milikh1994,
  author = {Milikh, G. M. and Freeman, M. J. and Duncan, L. M.},
  title = {First estimates of HF-induced modifications of the D region by the HF Active Auroral Research Program facility},
  journal = {Radio Science},
  year = {1994},
  volume = {29},
  number = {5},
  pages = {1355-1362},
  url = {http://dx.doi.org/10.1029/94RS01566},
  doi = {10.1029/94RS01566}
}
Muldrew DB (1994), "Correction to “Characteristics of the coupled Z mode at Arecibo” by D. B. Muldrew", Radio Science. Vol. 29(3), pp. 673-674.
BibTeX:
@article{Muldrew1994,
  author = {D. B. Muldrew},
  title = {Correction to “Characteristics of the coupled Z mode at Arecibo” by D. B. Muldrew},
  journal = {Radio Science},
  year = {1994},
  volume = {29},
  number = {3},
  pages = {673-674},
  url = {http://dx.doi.org/10.1029/93RS03593},
  doi = {10.1029/93RS03593}
}
Osterman GB, Heelis RA and Bailey GJ (1994), "Modeling the formation of intermediate layers at Arecibo latitudes", Journal of Geophysical Research: Space Physics. Vol. 99(A6), pp. 11357-11365.
Abstract: By using a modified version of the ionospheric model described by Bailey and Sellek (1990), we model the formation of intermediate ionization layers due to meridional neutral winds in the valley region between the E and F regions. The calculations are performed on a single field line with L = 1.4, in order to compare the results with observations of intermediate layers from the incoherent scatter radar at Arecibo. The winds are given a sinusoidal variation in altitude, and the effects of the wind amplitude and wavelength on layer formation are examined. Nighttime ionization rates are artificially specified to correspond with observed rates in the region. Our results show that tidal like meridional wind profiles act to deplete the apparent background ionospheric number density as well as enhance the number density in the intermediate layer. Thus the layer appears as an enhancement above a background that is much smaller than the background that would be present in the absence of a wind. In this way, layers with relatively high molecular ion concentrations can exist. Intermediate layers are seen to form at nulls in the neutral wind altitude profile, but in the altitude region above roughly 160 km this null need not coincide with a zero in the field-aligned ion velocity.
BibTeX:
@article{Osterman1994,
  author = {Osterman, G. B. and Heelis, R. A. and Bailey, G. J.},
  title = {Modeling the formation of intermediate layers at Arecibo latitudes},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1994},
  volume = {99},
  number = {A6},
  pages = {11357-11365},
  url = {http://dx.doi.org/10.1029/94JA00519},
  doi = {10.1029/94JA00519}
}
Tepley CA (1994), "Neutral winds of the middle atmosphere observed at Arecibo using a Doppler Rayleigh lidar", Journal of Geophysical Research: Atmospheres. Vol. 99(D12), pp. 25781-25790.
Abstract: We present our observations of the neutral winds of the tropical middle atmosphere that we made over a 2-year period at the Arecibo Observatory in Puerto Rico. The technique involves the use of a Doppler Rayleigh lidar that measures the spectral shift of the backscattered laser light up to 60 km altitude. We generally find the winds to have discernible patterns although we also observe a high degree of daily variability. We discuss these seasonal patterns and the daily variability and compare our measurements with balloon radiosonde measurements and with models of the tropical middle atmosphere.
BibTeX:
@article{Tepley1994,
  author = {Tepley, Craig A.},
  title = {Neutral winds of the middle atmosphere observed at Arecibo using a Doppler Rayleigh lidar},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1994},
  volume = {99},
  number = {D12},
  pages = {25781-25790},
  url = {http://dx.doi.org/10.1029/94JD02213},
  doi = {10.1029/94JD02213}
}
Bird J, Shepherd G and Tepley C (1993), "Comparison of lower thermospheric winds measured by a Polarizing Michelson Interferometer and a Fabry-Perot spectrometer during the AIDA campaign ", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 313-324.
BibTeX:
@article{Bird1993313,
  author = {J.C Bird and G.G Shepherd and C.A Tepley},
  title = {Comparison of lower thermospheric winds measured by a Polarizing Michelson Interferometer and a Fabry-Perot spectrometer during the AIDA campaign },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {313-324},
  url = {http://www.sciencedirect.com/science/article/pii/0021916993900716},
  doi = {10.1016/0021-9169(93)90071-6}
}
Brosnahan J and Adams G (1993), "The MAPSTAR imaging Doppler interferometer (IDI) radar: description and first results", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 203-228.
Abstract: MAPSTAR is a medium-frequency imaging Doppler interferometer (IDI) radar. In this paper we describe the radar and present results from 34.5 h of data taken during the AIDA campaign in Puerto Rico during April 1989. The IDI method uses several independent antennas and receivers, pulsed sounding, range-gating, Doppler sorting and spatial interferometry to determine a three-dimensional Doppler image of the rf scatterers within the volume being illuminated. The analysis characterizes any perturbation in the index of refraction that returns rf energy (clear-air turbulence, scattering from striations, meteor trails, etc.) in terms of the three-dimensional locations, Doppler velocities, and scattering amplitudes and phases of a number of apparent points in space, called scattering points
BibTeX:
@article{Brosnahan1993,
  author = {J.W Brosnahan and G.W Adams},
  title = {The MAPSTAR imaging Doppler interferometer (IDI) radar: description and first results},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {203-228},
  url = {http://www.sciencedirect.com/science/article/pii/0021916993900679},
  doi = {10.1016/0021-9169(93)90067-9}
}
Buonsanto MJ and Foster JC (1993), "Effects of magnetospheric electric fields and neutral winds on the low-middle latitude ionosphere during the March 20-21, 1990, storm", Journal of Geophysical Research: Space Physics. Vol. 98(A11), pp. 19133-19140.
Abstract: During the geomagnetic storm of March 20-21, 1990, substorm activity is clearly evident in magnetometer data collected during the night at the middle- and low-latitude stations Fredericksburg (38.2°N, 282.6°E) and San Juan (18.1°N, 293.8°E). At the same time, incoherent scatter radars at Millstone Hill (42.6°N, 288.5°E) and Arecibo (18.3°N, 293.25°E) observed ionospheric storm effects, which included the penetration of magnetospheric electric fields and disturbance neutral winds to the latitude of Arecibo. The eastward electric fields associated with the substorm disturbances result in increases in the F2 peak height (hmF2) at Arecibo. Decreases in hmF2 follow as a result of increased downward diffusion and/or the effects of an ion drag induced poleward wind. During the intervals between the electric field penetration events, equatorward surges in the neutral wind result in westward electric fields by the disturbance dynamo mechanism. At these times the horizontal ionization drifts are not as strong as the neutral winds, apparently because of a partial shorting out of the dynamo electric fields as a result of some E region conductivity. The anticorrelation between the components of the ion drift parallel (Vp) and perpendicular to the magnetic field in the northward direction (VLN) results in approximately horizontal (constant altitude) ion drift motion throughout the interval. Calculations of spatial gradients in the electron density and in the components of the ion velocity are carried out using the multi-directional incoherent scatter observations at Arecibo. The results show that the variations in electron density during this disturbed interval follow closely the motion term in the F2 region continuity equation, with both advection of spatial gradients and divergence of the ion flow important at times.
BibTeX:
@article{Buonsanto1993,
  author = {Buonsanto, M. J. and Foster, J. C.},
  title = {Effects of magnetospheric electric fields and neutral winds on the low-middle latitude ionosphere during the March 20-21, 1990, storm},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A11},
  pages = {19133-19140},
  doi = {10.1029/93JA01807}
}
Chilson PB, Ulbrich CW, Larsen MF, Perillat P and Keener JE (1993), "Observations of a Tropical Thunderstorm Using a Vertically Pointing, Dual-Frequency, Collinear Beam Doppler Radar", Journal of Atmospheric and Oceanic Technology. Vol. 10, pp. 663-673.
BibTeX:
@article{Chilson1993,
  author = {P. B. Chilson and C. W. Ulbrich and M. F. Larsen and P. Perillat and J. E. Keener},
  title = {Observations of a Tropical Thunderstorm Using a Vertically Pointing, Dual-Frequency, Collinear Beam Doppler Radar},
  journal = {Journal of Atmospheric and Oceanic Technology},
  year = {1993},
  volume = {10},
  pages = {663-673},
  doi = {10.1175/1520-0426(1993)010}
}
Cho JYN, Swartz WE, Kelley MC and Miller CA (1993), "Cupri observations of PMSE during Salvo B of NLC-91: Evidence of both partial reflection and turbulent scatter", Geophysical Research Letters. Vol. 20(20), pp. 2291-2294.
Abstract: During the first rocket sequence (called Salvo B) of the NLC-91 campaign, the Cornell University Portable Radar Interferometer (CUPRI) observed two simultaneously occurring layers of Polar Mesosphere Summer Echoes (PMSE). During the time of the Turbo B flight, the high time-resolution CUPRI Doppler spectra exhibited sawtooth-like discontinuities in the lower layer which we interpret to be a distorted partial reflection layer which was advected across the radar beam. The upper layer, on the other hand, appeared to be caused by turbulent scatter and we estimate the turbulence energy dissipation rate in the upper layer at the time of the Turbo B flight to have been approximately 0.04 W/kg. Furthermore, a shift in the antenna beam direction from vertical to 8° off zenith revealed an aspect sensitivity of approximately 5 dB in the lower layer but none in the upper layer. We conclude that, at this particular time, turbulent scatter was responsible for the upper layer while some form of partial reflection was dominant in the lower layer.
BibTeX:
@article{Cho1993,
  author = {Cho, John Y. N. and Swartz, Wesley E. and Kelley, Michael C. and Miller, Clark A.},
  title = {Cupri observations of PMSE during Salvo B of NLC-91: Evidence of both partial reflection and turbulent scatter},
  journal = {Geophysical Research Letters},
  year = {1993},
  volume = {20},
  number = {20},
  pages = {2291-2294},
  url = {http://dx.doi.org/10.1029/93GL01600},
  doi = {10.1029/93GL01600}
}
Cho JYN and Kelley MC (1993), "Polar mesosphere summer radar echoes: Observations and current theories", Reviews of Geophysics. Vol. 31(3), pp. 243-265.
Abstract: The remarkably strong radar echoes from the summer polar mesosphere have been an enigma to atmospheric and radar scientists since their discovery more than a decade ago. Since then, more sophisticated radar experiments and in situ rocket measurements have shed some light on the underlying physics and chemistry, and theories have been formulated to explain the generation of the intense radar backscatter and the remarkable physical conditions associated with it. First, we review the key observations and examine the proposed theories. We then evaluate the progress that has been made in understanding this phenomenon and explore its connection to global change, to the newly recognized material referred to as a dusty plasma, and to the highest clouds in the Earth's atmosphere. Finally, we end with suggestions for future research.
BibTeX:
@article{Cho1993a,
  author = {Cho, John Y. N. and Kelley, Michael C.},
  title = {Polar mesosphere summer radar echoes: Observations and current theories},
  journal = {Reviews of Geophysics},
  year = {1993},
  volume = {31},
  number = {3},
  pages = {243-265},
  url = {http://dx.doi.org/10.1029/93RG01535},
  doi = {10.1029/93RG01535}
}
Djuth F and Elder J (1993), "The VHF meteor radar system used during the Arecibo Initiative in Dynamics of the Atmosphere (AIDA) campaign '89", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 229-239.
Abstract: During the AIDA 1989 campaign, a 49.92 MHz meteor scatter radar was deployed in the Lajas valley of southwest Puerto Rico. The principal motivation for this effort was to provide support for a validation study of neutral winds measurement techniques in the mesosphere. This paper provides a description of the VHF radar design, the associated radar processor and the methods used to analyze the data. Procedures adopted to check the integrity of the system are discussed along with the limits of the measurement process. Initial observations of mesospheric quantities are presented to illustrate system performance.
BibTeX:
@article{Djuth1993,
  author = {F.T Djuth and J.H Elder},
  title = {The VHF meteor radar system used during the Arecibo Initiative in Dynamics of the Atmosphere (AIDA) campaign '89},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {229-239},
  doi = {10.1016/0021-9169(93)90068-A}
}
Fejer BG (1993), "F region plasma drifts over Arecibo: Solar cycle, seasonal, and magnetic activity effects", Journal of Geophysical Research: Space Physics. Vol. 98(A8), pp. 13645-13652.
Abstract: We have used Arecibo incoherent scatter measurements from 1981 to 1990 to determine the characteristics of low-latitude F region plasma drifts. The measurements show large day-to-day variability even during magnetically quiet periods. The average poleward/perpendicular plasma drifts do not change significantly with season and solar cycle except in the midnight-morning sector. The zonal drifts show clear solar cycle and seasonal effects. The afternoon-nighttime eastward drifts increase with solar flux; the westward drifts in the early morning-afternoon sector show a large increase from summer to winter but are independent of solar activity. The two perpendicular velocity components also respond differently to magnetic activity. The average northward/perpendicular drifts decrease with magnetic activity during the day but do not exhibit a systematic response at night. The zonal component shows increased westward drifts occurring predominantly at night. The plasma drifts along the magnetic field lines exhibit large altitudinal and seasonal variations, particularly near solar minimum, and are generally anticorrelated with the perpendicular/north drifts. The drift patterns observed by the Arecibo and the middle and upper atmosphere radars have significantly different seasonal dependence. This can be explained by electrodynamic effects in the corresponding local and conjugate ionospheres. The large longitudinal variation of the quiet time F region plasma drifts results from the displacement between the geographic and dip equators and from magnetic field declination effects. In general, the longitudinal variation should also depend on magnetic activity.
BibTeX:
@article{Fejer1993,
  author = {Fejer, B. G.},
  title = {F region plasma drifts over Arecibo: Solar cycle, seasonal, and magnetic activity effects},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A8},
  pages = {13645-13652},
  url = {http://dx.doi.org/10.1029/93JA00953},
  doi = {10.1029/93JA00953}
}
Fesen CG, Hagan ME, Tepley CA and Roble RG (1993), "On the coupling between the lower and the upper thermosphere during the First Lower Thermosphere Coupling Study", Journal of Geophysical Research: Space Physics. Vol. 98(A2), pp. 1545-1558.
Abstract: Simultaneous observations of the neutral winds and temperatures and electron densities in the upper and lower thermosphere are presented. The measurements were made at Arecibo and Millstone Hill during the first Lower Thermosphere Coupling Study (LTCS 1) campaign in September 1987. The observations show a great deal of day-to-day variability possibly due to the geomagnetic activity which occurred during the period; storm effects are discernible in the data at low altitudes (near 120 km) even at low latitudes (near 18°N). Theoretical simulations of the period were attempted by the National Center for Atmospheric Research thermosphere-ionosphere general circulation model. A novel development was the use in the model of lower boundary conditions representative of the upward propagating semidiurnal tides based on the LTCS 1 mesosphere-lower thermosphere observations. The upward propagating diurnal 1,1 mode was also included in the model. Simulations of the low and mid latitudes did not substantially improve with the use of lower boundary conditions derived from the measurements. The model was also unable to reproduce the observations in both the lower and upper thermosphere. This may be partially due to the effects of geomagnetic activity on the atmospheric fields, since the observational period included two intervals of geomagnetic disturbances. In the lower thermosphere, resolution of the discrepancies between the data and model predictions may require the extension of the model to lower altitudes. At present, the model predictions in the lower thermosphere are strongly dependent on the lower boundary conditions. The model predicts that diurnal waves are not negligible in analysis of lower thermosphere data; indeed, near 100 km at the model location of Arecibo, the diurnal wave amplitudes of the meridional winds were predicted to be greater than the semidiurnal. Investigation of the model predictions awaits the development of techniques to obtain observations of at least 24 hours duration in the lower thermosphere and the extension of the theoretical models to lower altitudes.
BibTeX:
@article{Fesen1993,
  author = {Fesen, C. G. and Hagan, M. E. and Tepley, C. A. and Roble, R. G.},
  title = {On the coupling between the lower and the upper thermosphere during the First Lower Thermosphere Coupling Study},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A2},
  pages = {1545-1558},
  url = {http://dx.doi.org/10.1029/92JA02194},
  doi = {10.1029/92JA02194}
}
He X, Kerr RB, Bishop J and Tepley CA (1993), "Determining exospheric hydrogen density by reconciliation of H-alpha measurements with radiative transfer theory", Journal of Geophysical Research: Space Physics. Vol. 98(A12), pp. 21611-21626.
Abstract: The singly scattered resonant fluorescent component of the geocoronal Balmer-alpha (H&alpha;) emission is obtained by subtracting the multiply scattered component of H&alpha;, determined by a radiative-transfer (RT) model, from H&alpha; measurements. Exospheric column abundance then follows a straightforward single-scattering calculation. The reality of that abundance depends upon the validity of the model exosphere used by the RT model, upon the validity of the estimated solar Ly-&beta; flux, and upon the statistical measurement errors. Iterative adjustments of the hydrogen density ([H]) profile input to the RT model, converging to a best fit to H&alpha; observations, generate a unique atmosphere best matching model intensity to measured H&alpha;, brightnesses. Applying this method to ground-based measurements of the geocoronal H&alpha; emission made at Arecibo, Puerto Rico, in 1988, we find that the best estimated multiply and singly scattered components of H&alpha; are about 85 and 60%, respectively, in excess of the initial model values, while the derived [H] is generally in agreement with the initial model [H] at lower altitudes and about 35% higher than the initial model [H] at higher altitudes. Examination of the iteration technique sensitivity indicates that the neutral temperature prescribed by the MSIS-83 model and the solar Ly-&beta; flux estimated by a correlation relation are the parameters with the principal impact on the determined [H]. In addition, the examination shows that these parameters impact the RT-calculated intensity components. Because convergence of the iteration technique is insensitive to the initial model guess for most cases, the technique is capable of accurately determining [H] from H&alpha; measurements, particularly if the temperature is simultaneously measured and the line center solar Ly-&beta; flux is known.
BibTeX:
@article{He1993,
  author = {He, Xiangqun and Kerr, Robert B. and Bishop, James and Tepley, Craig A.},
  title = {Determining exospheric hydrogen density by reconciliation of H-alpha measurements with radiative transfer theory},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A12},
  pages = {21611-21626},
  url = {http://dx.doi.org/10.1029/93JA01854},
  doi = {10.1029/93JA01854}
}
Hecht JH, Kane TJ, Walterscheid RL, Gardner CS and Tepley C (1993), "Simultaneous nightglow and Na lidar observations at Arecibo during the AIDA-89 campaign", Journal of Atmospheric and Terrestrial Physics. Vol. 55, pp. 409-423.
Abstract: Simultaneous nightglow and Na lidar observations made at Arecibo during the AIDA-89 campaign are reported from between 0000 and 0530 LT (Local Time) on 6 April 1989 and on 9 April 1989. On 9 April the observations are consistent with the presence of a large amplitude 8.5 km vertical wavelength, 4 h period wave propagating through the 85–91 km region. A lower amplitude 80 min period wave is also observed. The results imply that the O2 atmospheric band intensity peaked near 91 km while the OH Meinel (6,2) band intensity peaked near 85 km. The OH Meinel temperature and intensity are 160° out of phase which can be explained by low eddy diffusion and high ozone densities near the mesopause. The integrated Na abundance from 87 to 89 (90–92) km correlates well with the OH Meinel (O2 atmospheric) band intensity. On 5–6 April the OH Meinel and O2 atmospheric band intensities are not well correlated. The OH Meinel intensity is correlated with the integrated Na abundance from 86 to 88 km. Both the Na and OH measurements reveal the presence of an approximately 1 h period wave. The OH temperature data appear to be consistent with the OH Meinel band originating near 85 km. The O2 atmospheric band data show the presence of a 2 h period wave. The integrated Na abundance data suggest that the O2 atmospheric band peaks between 90 and 94 km. A large sporadic Na event which occurs near 6 UT appears related to the presence of a gravity wave near 95 km. In all of the observed waves there is good agreement between the wave parameters derived separately by the optical airglow and Na lidar techniques.
BibTeX:
@article{Hecht1993,
  author = {Hecht, J H and Kane, T J and Walterscheid, R L and Gardner, C S and Tepley, C},
  title = {Simultaneous nightglow and Na lidar observations at Arecibo during the AIDA-89 campaign},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  pages = {409-423},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390077C},
  doi = {10.1016/0021-9169(93)90077-C}
}
Hines C (1993), "Pseudosaturation of gravity waves in the middle atmosphere: an interpretation of certain lidar observations ", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 441-445.
Abstract: Irregular winds of the middle atmosphere, commonly attributed to gravity waves, often exhibit a vertical-wavenumber (m) spectral form approximating to Km-3 at sufficiently large m, with K a constant found to be relatively unvarying with time, location and even height. This behavior is widely believed to result from some saturation process, but the physical mechanism remains a matter for debate. There now exist three theories:
1.(a) linear instability,
2.(b) nonlinear wave-induced diffusion, and
3.(c) nonlinear waveinduced Doppler spreading. Each has produced the Km-3 form (but only as an approximation in the case of Doppler spreading) and values of K within a factor of three of one another and of observed values.
New data have revealed circumstances in which an approximation to the form Km-3 is again found, suggestive of saturation, but with values of K that increase by a factor of 5 or 10 on moving from the stratopause to the mesopause region. This height variation is incompatible with theories (a) and (b) if the m-3 form is taken to be induced by the corresponding saturation process (rather than by source spectra), but is shown here to be compatible with the Doppler-spread theory. Because of the continued growth of K with height, which must ultimately cease, the observations and corresponding theory are taken to represent pseudosaturation rather than fully developed saturation per se.
BibTeX:
@article{Hines1993,
  author = {C.O Hines},
  title = {Pseudosaturation of gravity waves in the middle atmosphere: an interpretation of certain lidar observations },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {441-445},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390079E},
  doi = {10.1016/0021-9169(93)90079-E}
}
Hines C, Adams G, Brosnahan J, Djuth F, Sulzer M, Tepley C and Baelen JV (1993), "Multi-instrument observations of mesospheric motions over Arecibo: comparisons and interpretations ", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 241-287.
Abstract: The MF/HF partial-reflection technique of observing the mesosphere and lower thermosphere has been employed for more than two decades to measure motions, but there has never been complete agreement as to what motions were being detected. This paper reports on observations made during a major international campaign—AIDA '89—that was initiated with the objective of resolving this question.
The partial-reflection system employed was an Imaging Doppler Interferometer operating at 3.175 MHz, but it stands here as a prototype for all MF/HF partial-reflection radar systems: its raw data were analyzed both in its own basic mode, derived on the assumption that it sees wind-borne multiple scattering centers and in modes adopted by other interferometric and ‘spaced antenna’ systems. The motions thus revealed are compared here with those found by what we consider to be more certain measurers of winds: an incoherent-scatteer radar at heights of 65–95 km, a meteor-wind radar at heights of 80–100 km and a Fabry-Perot interferometer measuring 0(1S) emissions near a height of 97 km.
Comparisons of the different sets of observations oblige us to conclude that
1.(1) MF/HF partial-reflection systems may be expected to give a good representation of ambient winds up to a height of about 80 km;
2.(2) they fail to give a consistently reliable measurement of the ambient winds above a height of about 80 km
3.(3) they yield, at the greater heights, what appears in our data to be some convolution of the horizontal phase velocities of atmospheric gravity waves, with the wave spectrum having been modified by passage through the underlying wind system and containing, on occasion, locally generated Kelvin-Helmholtz waves; and
4.(4) when the underlying winds change, the local wave spectrum will change in response and, in MF/HF partial-reflection measurements, will give the appearance of a changing local wind: if the underlying winds undergo tidal changes, the wave spectrum will undergo tide-like changes that will masquerade as true tidal winds.
These results are, of course, limited to a single site over a limited period of observation. Nevertheless, taken at face value they suggest that current methods of data reduction are inappropriate for partial-reflection velocities at heights above 80 km and that new methods of data reduction, perhaps extending certain older methods that have been applied successfully in the past to total-reflection measurements, should be employed in their place if the full potential of the MF/HF partial-reflecton technique is to be realized.
BibTeX:
@article{Hines1993a,
  author = {C.O Hines and G.W Adams and J.W Brosnahan and F.T Djuth and M.P Sulzer and C.A Tepley and J.S Van Baelen},
  title = {Multi-instrument observations of mesospheric motions over Arecibo: comparisons and interpretations },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {241-287},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390069B},
  doi = {10.1016/0021-9169(93)90069-B}
}
Hines CO (1993), "The Saturation of Gravity Waves in the Middle Atmosphere. Part IV: Cutoff of the Incident Wave Spectrum", Journal of the Atmospheric Sciences. Vol. 50, pp. 3045-3060.
Abstract: A Doppler-spread theory for the saturation of middle atmosphere gravity waves was presented in an earlier member of this sequence of papers. It employed a model in which a broad spectrum of waves subject to linear theory is incident from below. The spectral distribution (in vertical wavenumber m) is deformed, as it propagates upward, in response to the growing importance of the Eulerian advective nonlinearity imposed on each wave by the total wave-induced wind. The deformation is such as to statistically spread the spectrum towards larger m, with the largest-m waves being progressively obliterated in quasi-critical-layer interactions. The model invoked a cutoff of the incident spectrum at a vertical wavenumber specified as lying in the range 0.5–1.0 times the local buoyancy frequency divided by the rms wind speed, with the choice 0.5 being adopted tentatively. A qualitative argument for the chosen cutoff wavenumber was presented but was not supported by any more certain quantitative analysis at the time. The present paper derives an analytic form for the cutoff function, illustrates it in application, and provides quantitative support for a value possibly as low as 0.5 in the stratosphere and a value possibly as high as 1.0 in the mesosphere. In addition, it slightly recasts the heuristic approach to the Doppler-spread analysis, and it admits to certain difficulties, associated with the largest-m waves, whose circumvention appears to require a far more detailed analysis of wave-wave interaction through the advective nonlinearity.
BibTeX:
@article{Hines1993b,
  author = {Hines, C O},
  title = {The Saturation of Gravity Waves in the Middle Atmosphere. Part IV: Cutoff of the Incident Wave Spectrum},
  journal = {Journal of the Atmospheric Sciences},
  year = {1993},
  volume = {50},
  pages = {3045-3060},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281993%29050%3C3045%3ATSOGWI%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1993)050}
}
Hines CO and Tarasick DW (1993), "On the nonlinear response of airglow to atmospheric gravity waves", Journal of Geophysical Research: Space Physics. Vol. 98(A11), pp. 19127-19131.
Abstract: An attempt is made to clarify the role that may be played by nonlinearities in airglow fluctuations induced by atmospheric gravity waves.
BibTeX:
@article{Hines1993c,
  author = {Hines, Colin O. and Tarasick, David W.},
  title = {On the nonlinear response of airglow to atmospheric gravity waves},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A11},
  pages = {19127-19131},
  url = {http://dx.doi.org/10.1029/93JA00219},
  doi = {10.1029/93JA00219}
}
Isham B and Hagfors T (1993), "Observations of the temporal and spatial development of induced and natural plasma lines during HF modification experiments at Arecibo using chirped incoherent scatter radar", Journal of Geophysical Research: Space Physics. Vol. 98(A8), pp. 13605-13625.
Abstract: Observations were made of the HF-modified ionosphere over Arecibo during the daytime on March 4, 1987 and April 6-8, 1988, and during the nighttime on April 13 and 14 and 14 and 15, 1988, using chirped incoherent scatter radar (ISR). The daytime observations show a difference in the frequencies of the HF-induced plasma line (HFPL) and the photoelectron-enhanced (natural) plasma line (PEPL) at the same height of the order of 100 kHz. In addition, the daytime HFPL originates within about 200 m of the reflection height (that is, the O mode cutoff), often within 20 ms of HF turn-on, and may remain at that location for many seconds. A second HFPL source region was sometimes observed to form between approximately 1 and 4 km below the usual source region after 5 to 10 s of heating. During the nighttime, rapidly changing regions of HF-induced plasma lines spread over more than 3 km in height were observed; the existence of these regions appears to be strongly dependent on HF heating power. At times, frequency shifting and broadening of the PEPL during heating was noted; the shift in frequency is due to increasing electron temperature and the frequency broadening to the appearance of short-scale density striations. These effects continued even during periods when the heater remained on and the HF-induced line was not observed by the radar.
BibTeX:
@article{Isham1993,
  author = {Isham, B. and Hagfors, T.},
  title = {Observations of the temporal and spatial development of induced and natural plasma lines during HF modification experiments at Arecibo using chirped incoherent scatter radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A8},
  pages = {13605-13625},
  url = {http://dx.doi.org/10.1029/93JA00879},
  doi = {10.1029/93JA00879}
}
Kane T, Gardner C, Znou Q, Mathews J and Tepley C (1993), "Lidar, radar and airglow observations of a prominent sporadic Na/sporadic E layer event at Arecibo during AIDA-89 ", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 499-511.
Abstract: Sporadic Na (Na,) layer events were frequently identified during 160 h of lidar observations at Arecibo in January, March and April 1989. Most were accompanied by sporadic E (E.) layers. The most spectacular NasEs, event occurred on the night of 30–31 March when both the Na and electron abundances between 90 and 100 km increased by approximately 700% during a period of 2.25 h starting at 2100 LST. The maximum Na density was almost 42,000 cm3. The vertical and temporal structure of the Na and electron densities were remarkably similar during the event. The ratio of the average Na enhancement to the electron density varied from a maximum of 3.5 Na atoms/electron at 98 km to about 0.5 Na atoms/ electron below 94 km. Between 93 and 97 km the electron enhancement preceded the Na enhancement by 15–30 min. Above 97 km and below 93 km the Na and electron density variations were in phase. The data suggest that the Es, layer triggered the release of Na from a reservoir, but the Es layer was not the source of the major Nas layer. Two minor Nas layers were observed between 101 and 107 km after midnight LST which were also accompanied by intense s layers and enhancements of the O(1S) emission intensities. The abundances of these high altitude Nas layers were less than 1% of the electron abundances. These Na, layers appear to be caused by the conversion of Na in the Es layer to Na through a set of clustering reactions involving N2 CO2 and H2O.
BibTeX:
@article{Kane1993,
  author = {T.J Kane and C.S Gardner and Q Znou and J.D Mathews and C.A Tepley},
  title = {Lidar, radar and airglow observations of a prominent sporadic Na/sporadic E layer event at Arecibo during AIDA-89 },
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {499-511},
  doi = {10.1016/0021-9169(93)90084-C}
}
Kieffaber L, Friesen D, Knutson D and Peterson A (1993), "Short gravity wave periodicities during AIDA", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 341-354.
BibTeX:
@article{Kieffaber1993,
  author = {L.M Kieffaber and D.R Friesen and D.L Knutson and A.W Peterson},
  title = {Short gravity wave periodicities during AIDA},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {341-354},
  doi = {10.1016/0021-9169(93)90073-8}
}
Kohl H, Kopka H, Stubbe P and Rietveld M (1993), "Introduction to ionospheric heating experiments at Tromso-II. Scientific problems", Journal of Atmospheric and Terrestrial Physics . Vol. 55, pp. 601-613.
Abstract: In the first section the theory of parametric decay instabilities (PDI) is briefly described. Then results of joint heating/incoherent scatter observations at TromsÜ are presented. It turns out that most of the observed features are in good agreement with that theory, while some others remain still unexplained. Among the latter features the most striking is the existence of a ‘space-time blob structure’, which means that the time variation of scattered power from adjacent altitudes seems to be correlated. Experiments at Arecibo often lead to results different from ours. Some scientists in the field explain these observations in terms of a ‘strong turbulence’ in which also caviton formation is involved. We think that most of the TromsÜ results can be adequately explained by the parametric decay process.
BibTeX:
@article{Kohl1993,
  author = {H. Kohl and H. Kopka and P. Stubbe and M.T. Rietveld},
  title = {Introduction to ionospheric heating experiments at Tromso-II. Scientific problems},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  pages = {601-613},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390008M},
  doi = {10.1016/0021-9169(93)90008-M}
}
Kuo SP, Huang J and Lee MC (1993), "On the altitude of the HF-enhanced plasma lines", Journal of Geophysical Research: Space Physics. Vol. 98(A7), pp. 11671-11676.
Abstract: The height of the HF-enhanced plasma lines (HFPLs) has been observed to be greater than that of the photon-enhanced natural plasma lines by 1 km or so at Arecibo, Puerto Rico. Besides the development of HFPLs affected strongly by that of the short-scale field-aligned irregularities (SFAIs) has been indicated in the recent Arecibo heating experiments. These outstanding features of HFPLs can be reasonably understood in terms of the proposed instability process which is elucidated in the present paper. This instability involves a four-wave interaction process whereby a parallel propagating (i.e. k--//B--0 ) Langmuir pump wave excites two obliquely propagating daughter Langmuir waves together with a purely growing field-aligned mode (density irregularities). The field-aligned mode can further scatter the propagating Langmuir waves to render even larger propagation angles leading to the detection of HFPLs. The parallel propagating Langmuir waves originate from the excitation of the parametric decay instability by the HF heater wave near its reflection height. Since the HFPLs were detected by the 430-MHz radar, while the SFAIs by a portable 49.92-MHz backscatter radar, the thresholds and growth rates of the instability are calculated separately for these two cases. One case is for the excitation of the Langmuir sidebands having a scale length of 42 cm and a propagation angle of 23° (which leads to HFPLs after being scattered off the 1.1-m field-aligned density irregularity), and the other case for the generation of the 3-m SFAIs. The threshold field of the instability leading to the generation of HFPLs is about 0.15 V/m. It is also found that the growth rate of the HFPLs is slightly greater than twice that of the 3-m SFAIs and that it takes a few milliseconds for the HFPLs to develop. Further, the proposed instability process occurs at an altitude about 1.2 km higher than the matching height determined by the dispersion relation of the HFPLs when the heater wave at 5.1 MHz is employed. Based on these results, the puzzling height difference between the HFPLs and the photon- enhanced natural plasma lines as well as the correlation between the HFPLs and SFAIs can be explained consistently.
BibTeX:
@article{Kuo1993,
  author = {Kuo, S. P. and Huang, J. and Lee, M. C.},
  title = {On the altitude of the HF-enhanced plasma lines},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1993},
  volume = {98},
  number = {A7},
  pages = {11671-11676},
  url = {http://dx.doi.org/10.1029/93JA00431},
  doi = {10.1029/93JA00431}
}
Mathews J, Morton Y and Zhou Q (1993), "Observations of ion layer motions during the AIDA campaign", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 447-457.
BibTeX:
@article{Mathews1993,
  author = {J.D Mathews and Y.T Morton and Q Zhou},
  title = {Observations of ion layer motions during the AIDA campaign},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {447-457},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390080I},
  doi = {10.1016/0021-9169(93)90080-I}
}
Mathews J, Zhou Q, Philbrick C, Morton Y and Gardner C (1993), "Observations of ion and sodium layer coupled processes during AIDA", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 487 - 498.
Abstract: Extended measurements of the neutral sodium layer using lidar and of the lower ionosphere using Incoherent Scatter Radar were conducted at Arecibo during the spring 1989 AIDA campaign. We present results from four nights of these rather extensive, almost common volume, simultaneous observations of the 80–110 km altitude region. Although in each set of results there are unique features that appear to be associated with the diverse dynamics of the atmosphere, the general nocturnal motion of both the sodium and ion layers is controlled by the tidal wind. Additionally, there is often a very strong correlation between the presence of narrow ionization and narrow sodium layers below 100 km altitude. These sporadic E and sporadic sodium layers usually occur at the same heights and with a sometimes striking correspondence in the details of vertical and temporal structure. These details are seen most clearly in a series of time-height plots of sodium concentration over which are overlaid the corresponding time-height trajectories of the ionization layers. Included in this series of plots are the two most spectacular of the layering events observed during AIDA. The most intense of the events occurred on the night of 30–31 March and was characterized by ion and sodium layers, with about 6 km vertical extent, that formed near 95 km altitude. During this event the sodium column content was observed to increase by a factor of about 10, from 1.5–2.0 â 109 to 20 â 109 cm 2, in 90 min. The second of the major events occurred on the night of 5–6 April and was characterized by a strong vertical oscillation of the sodium layer with a peak-to-peak amplitude of 2–3 km and a period of 10.4 min. For contrast with the two major events and because of the completeness of the data sets, results from the nights of 4–5 April and 7–8 April are also given.
BibTeX:
@article{Mathews1993a,
  author = {J.D Mathews and Q Zhou and C.R Philbrick and Y.T Morton and C.S Gardner},
  title = {Observations of ion and sodium layer coupled processes during AIDA},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {487 - 498},
  note = {Arecibo initiative dynamics of the atmosphere, AIDA act '89 },
  url = {http://www.sciencedirect.com/science/article/pii/002191699390083B},
  doi = {10.1016/0021-9169(93)90083-B}
}
Melendez-Alvira DJ, Burnside RG and Walker JCG (1993), "Modeling the Arecibo nighttime F2 layer: 1. Overhead properties", Journal of Geophysical Research. Vol. 98A, pp. 5993-6011.
Abstract: The servo model of Rishbeth et al. (1978) is extended and applied to fit the height and plasma density of the nighttime F2 layer, as measured from the Arecibo Observatory in Puerto Rico during solar maximum by Burnside (1984). The model equations are integrated numerically to fit the observed peak height and density. Specifically, the fitting is made by applying a theoretical zonal current (or drift), as needed so as to match the observed F2 peak. Moreover, the applied current/drift employs the measured ion velocity, whereas the component due to the neutral wind is freely adjusted. An improvement over previous servo-model fits is made by considering the time variations in all the model neutral and plasma densities and temperatures. All the background neutral densities are obtained from the MSIS model (Hedin, 1987). The following results are obtained: (1) the model adequately reproduces the observed behavior of the F2 layer; (2) the additional terms in the extended servo-height equation affect the peak height computation by no more than 10% on average; (3) the applied current is generally eastward though it becomes westward during the postmidnight collapse or descent of the layer; (4) differences between model and optically measured meridional wind speeds appear to be related to the presence of large vertical shears in the wind; (5) the observed peak density can be reproduced to within 20% to 40% accuracy; and (6) variable plasmaspheric fluxes of the order of 1013 (m?2 s?1) contribute to the maintenance and variability of the nighttime peak density. Also, horizontally divergent plasma fluxes remove plasma away from the local F2 peak; however, this is relatively minor. The overall model fit to the data is improved with the ion-neutral collision frequency increased by 70% (Burnside et al., 1987).
BibTeX:
@article{Melendez-Alvira1993,
  author = {Melendez-Alvira, D J and Burnside, R G and Walker, J C G},
  title = {Modeling the Arecibo nighttime F2 layer: 1. Overhead properties},
  journal = {Journal of Geophysical Research},
  year = {1993},
  volume = {98A},
  pages = {5993-6011},
  url = {http://dx.doi.org/10.1029/92JA02790},
  doi = {10.1029/92ja02790}
}
Meriwether JW (1993), "Lidar observations of atmospheric dynamics in the troposphere and lower stratosphere over Arecibo", Journal of Geophysical Research: Atmospheres. Vol. 98(D11), pp. 20713-20723.
Abstract: A periodic wave structure with a vertical wave length typically 2 km between 14 and 23 km altitudes has been identified in lidar measurements of relative density profiles at 589 nm that were made by the University of Illinois group during the March/April AIDA 1989 campaign effort. The equivalent temperature fluctuations are several degrees in magnitude. Also seen are stratified aerosol layers at altitudes near 25 km with a vertical extent of ~1 km. Both of these phenomena show a downward phase speed between 1 and 3 cm s-1. The lower periodic structure is believed to be the same phenomenon seen previously in 430-MHz measurements of winds obtained at Arecibo Observatory. The source of this structure remains uncertain. Cornish and Larsen (1989) and Sato and Woodman (1982a) considered this structure to be a quasi-inertial long period wave. Hines (1989) proposed instead the identification of this structure with a stationary wave system generated by orographic waves created through the interaction of the subtropical trade winds with the mountainous terrain of Puerto Rico. The higher altitude feature seen in the AIDA lidar observations is believed to be an aerosol layer with a scattering ratio of about 1.15. An alternative explanation is clear air turbulence, but the signature of the 10 K fluctuation deduced from the lidar observations was not found in the San Juan balloon measurement of the temperature profile for the lower stratosphere.
BibTeX:
@article{Meriwether1993,
  author = {Meriwether, John W.},
  title = {Lidar observations of atmospheric dynamics in the troposphere and lower stratosphere over Arecibo},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1993},
  volume = {98},
  number = {D11},
  pages = {20713-20723},
  url = {http://dx.doi.org/10.1029/93JD02259},
  doi = {10.1029/93JD02259}
}
Milikh GM, Hinds JM and Duncan LM (1993), "A computer simulation of the production of an artificially ionized layer using the Arecibo facility", Radio Science. Vol. 28(6), pp. 1029-1038.
Abstract: A computer model simulating the formation of an artificially ionized layer in the atmosphere by a series of microwave pulses was developed and is presented. A modified version of the kinetic theory of the breakdown of air by a powerful microwave emission was incorporated into a model of electromagnetic propagation through the atmosphere by a converging ionizing microwave pulse. This model takes into consideration radio wave self-action as well as absorption and produces profiles of electron concentration formed in the atmosphere by both an isolated pulse and a series of pulses. Effects of varying the shape of the ionizing pulse are considered as well as the influence of the ambient electron concentration. Also, the dependence of the electron concentration on the energy and duration of the pulse is investigated. The possible increase in the rate of electron production is considered when using an intense pulse to initiate the breakdown followed by a series of pulses of lesser energy. The influence of the refraction of the microwave beam is estimated. The computer model presented shows that an artificial ionized layer of electrons reaching concentrations of the order of 108 cm-3 could be formed over a height range of 40-70 km, if the Arecibo antenna and radio facility were reconfigured so that it would be able to generate microwaves with f = 2.38 GHz and a power of approximately 1-4 MW. In addition, a pulse compressor would be used to form pulses with durations of approximately 0.1-0.15 us with a repetition frequency of 103 Hz.
BibTeX:
@article{Milikh1993,
  author = {Milikh, G. M. and Hinds, J. M. and Duncan, L. M.},
  title = {A computer simulation of the production of an artificially ionized layer using the Arecibo facility},
  journal = {Radio Science},
  year = {1993},
  volume = {28},
  number = {6},
  pages = {1029-1038},
  url = {http://dx.doi.org/10.1029/93RS00358},
  doi = {10.1029/93RS00358}
}
Morton Y, Mathews JD and Zhou Q (1993), "Further evidence for a 6-h tide above Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 55, pp. 459-465.
BibTeX:
@article{Morton1993a,
  author = {Morton, Y and Mathews, J D and Zhou, Q},
  title = {Further evidence for a 6-h tide above Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  pages = {459-465},
  doi = {10.1016/0021-9169(93)90081-9}
}
Morton Y and Mathews JD (1993), "Effects of the 13 - 14 March 1989 Geomagnetic Storm on the E Region Tidal Ion Layer Structure at Arecibo During AIDA", Journal of Atmospheric and Terrestrial Physics. Vol. 55, pp. 467-485.
BibTeX:
@article{Morton1993b,
  author = {Morton, Y and Mathews, J D},
  title = {Effects of the 13 - 14 March 1989 Geomagnetic Storm on the E Region Tidal Ion Layer Structure at Arecibo During AIDA},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  pages = {467-485},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390082A},
  doi = {10.1016/0021-9169(93)90082-A}
}
Muldrew DB (1993), "Characteristics of the coupled Z mode at Arecibo", Radio Science. Vol. 28(3), pp. 379-388.
Abstract: For propagation in the magnetic meridian plane at two particular angles of incidence near the vertical, the ordinary (O) electromagnetic mode couples into what Budden [1961] calls the extraordinary (X) mode and what more recently has been called the Z mode. One of the angles is northward of zenith and one is southward. These angles form the transition between O mode reflections at a “Spitze” where the wave frequency ? matches the plasma frequency ?p and reflection below the height where ? = ?p. If the O mode propagates southward from Arecibo, the coupled Z mode is reflected up to a few kilometers above the height of the Spitze; it then propagates downward through the Spitze height to a height where the group path is horizontal. Assuming a horizontal, plane-stratified uniformly varying ionosphere and no nonlinear effects, the refractive index and wavenormal direction approach constant finite values at this height and the wave remains electromagnetic in character; this is a new result which has not been previously reported. The group velocity is small, and the wave becomes heavily damped due to electron-ion collisions after several milliseconds. If the O wave propagates northward, the coupled Z mode is reflected a couple of hundred meters or less above the Spitze height; it then propagates downward through the Spitze height and approaches horizontally the height at which the Appleton-Hartree refractive index becomes infinite. For the same above mentioned assumptions, the Z mode converts gradually from electromagnetic to electrostatic in nature. The electrostatic or Langmuir mode attains a small downward component of group velocity and propagates downward for a few tens of meters while being heavily damped by electron-ion collisions. Neglecting damping and nonlinear effects, the intensity of the Z mode varies approximately inversely with group velocity. If the HF array near the Arecibo Observatory were modified to place the main or secondary beams in the coupling directions, the electric field due to the coupled Z wave could be enormous. Even weak transmissions from the array should produce a nonlinear region. It is thus difficult to say how much of the linear mode coupling description is valid before nonlinear effects dominate. The nonlinear effects might generate Langmuir waves of a similar frequency to the HF which could be detected by the Arecibo 430-MHz radar. Exciting new plasma line observations should thus be possible.
BibTeX:
@article{Muldrew1993,
  author = {Muldrew, D. B.},
  title = {Characteristics of the coupled Z mode at Arecibo},
  journal = {Radio Science},
  year = {1993},
  volume = {28},
  number = {3},
  pages = {379-388},
  url = {http://dx.doi.org/10.1029/92RS00273},
  doi = {10.1029/92RS00273}
}
Roper R, Adams G and Brosnahan J (1993), "Tidal winds at mesopause altitudes over Arecibo (18N, 67W), 5-11 April 1989 (AIDA '89)", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 289-312.
BibTeX:
@article{Roper1993,
  author = {R.G Roper and G.W Adams and J.W Brosnahan},
  title = {Tidal winds at mesopause altitudes over Arecibo (18N, 67W), 5-11 April 1989 (AIDA '89)},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {289-312},
  url = {http://www.sciencedirect.com/science/article/pii/002191699390070F},
  doi = {10.1016/0021-9169(93)90070-F}
}
Senft D, Hostetler C and Gardner C (1993), "Characteristics of gravity wave activity and spectra in the upper stratosphere and upper mesosphere at Arecibo during early April 1989", Journal of Atmospheric and Terrestrial Physics. Vol. 55, pp. 425-439. Elsevier Science.
Abstract: Twenty-nine hours of Rayleigh/Na lidar observations were obtained on six different nights from 6 to 11 April 1989 during the AIDA-89 Campaign. The lidar data were used to calculate the relative atmospheric density perturbations and their spectra. The average r.m.s. density perturbations for early April at Arecibo are 6.2% in the upper mesosphere (~ 83–103 km) and 1.4% in the upper stratosphere (20–45 km). In the upper mesosphere, the average r.m.s. vertical wind velocity, vertical shear variance of horizontal winds and Richardson number are, respectively, 2.8 m/s [28.5 (m/s)/km]2 and 0.63. In the stratosphere the average shear variance and Ri number are, respectively [7.9 (m/s)/km]2 and 9.7. The temporal frequency spectra of the mesopause region density perturbations exhibit power-law shapes with an average slope of ?1.76 and magnitude at ? = 2?(1h) of 1.2 (cycles/s)?1. The vertical wave number spectra also exhibit power-law shapes with average slopes of ?2.66 in the upper stratosphere and ?3.15 in the upper mesosphere. The magnitudes of the stratospheric spectra were consistently smaller than the mesopause spectra at all wave numbers less than m = 2?/(1 km). At m = 2?(4 km) the density spectra magnitudes were 5–12 times smaller in the upper stratosphere. The observed altitude variations in m-spectra magnitudes are inconsistent with linear instability theory which predicts that density spectra in the saturation regime vary only as N4m3. The observed spectra appear to be compatible with the recently published non-linear wave-induced diffusion and non-linear wave-induced Doppler spreading theories.
BibTeX:
@article{Senft1993,
  author = {D.C Senft and C.A Hostetler and C.S Gardner},
  title = {Characteristics of gravity wave activity and spectra in the upper stratosphere and upper mesosphere at Arecibo during early April 1989},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  publisher = {Elsevier Science},
  year = {1993},
  volume = {55},
  pages = {425-439},
  doi = {10.1016/0021-9169(93)90078-D}
}
Sulzer MP (1993), "A new type of alternating code for incoherent scatter measurements", Radio Science. Vol. 28(6), pp. 995-1001.
Abstract: An alternating code set is employed as one of several possible techniques used in incoherent scatter radar transmissions to obtain ambiguity-free measurements of autocorrelation functions or spectra with good range resolution. An alternating code set consists of several codes; typically, each successive radar pulse is modulated with a different code in the sequence. This technique is useful in other types of radar transmissions when the target is overspread, assuming the targets have certain statistical properties. Code sets for a new type of alternating code are presented for code lengths 8–12. This new type of alternating code differs from the first kind in two ways: it is subject to a slightly different condition for the elimination of ambiguity, and it is not restricted to lengths that are powers of 2. The new lengths are useful because they allow greater freedom in designing a multipurpose radar waveform best utilizing the available duty cycle of the radar. The alternating code technique is described in detail sufficient to allow an understanding of the two types and to show that the new condition for ambiguity-free measurements is a useful one. A search program was used to find the new sets; the aspects of the program important for decreasing the size of the search space are described. The code sets are presented, and their significance and uses are discussed.
BibTeX:
@article{Sulzer1993,
  author = {Sulzer, Michael P.},
  title = {A new type of alternating code for incoherent scatter measurements},
  journal = {Radio Science},
  year = {1993},
  volume = {28},
  number = {6},
  pages = {995-1001},
  url = {http://dx.doi.org/10.1029/93RS01918},
  doi = {10.1029/93RS01918}
}
Tepley CA, Sargoytchev S and Rojas R (1993), "The Doppler Rayleigh lidar system at Arecibo", IEEE Transactions on Geoscience and Remote Sensing. Vol. 31(1), pp. 36-47.
Abstract: The instrument structure and the operation of a Doppler Rayleigh lidar located at the Arecibo Observatory in Puerto Rico are described. The device consists of an injection seeded, frequency doubled, Nd:YAG laser coupled with a small Newtonian telescope and a single etalon, Fabry-Perot interferometer in its receiver. With this combination of transmitter and receiver, observations of the Doppler spectral components of the Rayleigh backscattered signal from the atmosphere are possible. Neutral wind and temperature up to mesospheric heights are presented. The improvements to the instrument that are underway, which will allow an increase in the temporal and spectral sampling of the winds, are discussed
BibTeX:
@article{Tepley1993,
  author = {Tepley, C A and Sargoytchev, S.I. and Rojas, R.},
  title = {The Doppler Rayleigh lidar system at Arecibo},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  year = {1993},
  volume = {31},
  number = {1},
  pages = {36-47},
  doi = {10.1109/36.210442}
}
Wang DY, Zhang SP, Wiens RH and Shepherd GG (1993), "Gravity waves from O2 nightglow during the AIDA '89 campaign III: effects of gravity wave saturation", Journal of Atmospheric and Terrestrial Physics. Vol. 55, pp. 397-408. Elsevier Science.
BibTeX:
@article{Wang1993,
  author = {Wang, D Y and Zhang, S P and Wiens, R H and Shepherd, G G},
  title = {Gravity waves from O2 nightglow during the AIDA '89 campaign III: effects of gravity wave saturation},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  publisher = {Elsevier Science},
  year = {1993},
  volume = {55},
  pages = {397-408},
  doi = {10.1016/0021-9169(93)90076-b}
}
Wiens R, Zhang S, Peterson R, Shepherd G, Tepley C, Kieffaber L, Niciejewski R and Hecht J (1993), "Simultaneous optical observations of long-period gravity waves during AIDA'89", Journal of Atmospheric and Terrestrial Physics . Vol. 55(3), pp. 325-340.
BibTeX:
@article{Wiens1993,
  author = {R.H Wiens and S.P Zhang and R.N Peterson and G.G Shepherd and C.A Tepley and L Kieffaber and R Niciejewski and J.H Hecht},
  title = {Simultaneous optical observations of long-period gravity waves during AIDA'89},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1993},
  volume = {55},
  number = {3},
  pages = {325-340},
  doi = {10.1016/0021-9169(93)90072-7}
}
Zhang S, Peterson R, Wiens R and Shepherd G (1993), "Gravity waves from O2 nightglow during the AIDA'89 campaign I: emission rate/temperature observations", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 355-375.
Abstract: The horizontal characteristics of 14 gravity waves, two evanescent and 12 internal, were derived from 12-direction simultaneous measurements of the O2(1E) (0-1) source airglow observations of a ground-based instrument, MORTI, during AIDA '89. The method used here is the Lomb-Scargle method for unevenly spaced data. The apparent wave periods were between 45 and 360 min, the horizontal wavelengths between 200 and 2900 km and the apparent horizontal wave speeds between 48 and 282 m/s. Since the fluctuations of the emission rate were much higher than those of temperature, the emission rate is a better diagnostic of gravity wave activity than temperature. The observed v values, the ratio of emission rate fluctuation to temperature fluctuation, lay between 3.5 and 5.5 and the fluctuations were generally in phase. Comparison with existing experimental and theoretical reports suggests the need for some improvement in theoretical treatments.
BibTeX:
@article{Zhang1993,
  author = {S.P Zhang and R.N Peterson and R.H Wiens and G.G Shepherd},
  title = {Gravity waves from O2 nightglow during the AIDA'89 campaign I: emission rate/temperature observations},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {355-375},
  doi = {10.1016/0021-9169(93)90074-9}
}
Zhang S, Wiens R and Shepherd G (1993), "Gravity waves from O2 nightglow during the AIDA'89 campaign II: numerical modeling of the emission rate/temperature ratio, n", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 377-395.
Abstract: The dependence of n, the ratio of emission rate fluctuation to temperature fluctuation, on the gravity wave parameters and chemical parameters is developed using a model for the O2 airglow's response to a gravity wave. The model is in the Eulerian frame of reference using the traditional linearization and perturbation method. Two photochemical mechanisms, the three-body recombination mechanism and the two-step transfer mechanism and two kinds of waves, evanescent and internal, are separately discussed in detail. Results of the model are compared with other existing models of n(O2) and found to be in agreement. The predictions of this model agree fairly well with the available gravity wave measurements in the magnitude of n, but the predicted phases are somewhat larger than those normally observed.
BibTeX:
@article{Zhang1993a,
  author = {S.P Zhang and R.H Wiens and G.G Shepherd},
  title = {Gravity waves from O2 nightglow during the AIDA'89 campaign II: numerical modeling of the emission rate/temperature ratio, n},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {377-395},
  doi = {10.1016/0021-9169(93)90075-A}
}
Zhou Q, Mathews J and Tepley C (1993), "A proposed temperature dependent mechanism for the formation of sporadic sodium layers", Journal of Atmospheric and Terrestrial Physics. Vol. 55(3), pp. 513-521.
Abstract: We examine the influence of temperature fluctuations on the formation of sporadic sodium layers (SSLs) with particular emphasis on AIDA (Arecibo Initiative in the Dynamics of the Atmosphere) results. We present evidence suggesting that sodium abundance is very sensitive to the temperature. A 10 K increase in mesopause temperature may double the sodium concentration. Thus the sodium profile may change significantly if appropriate thermal fluctuations due to tides and/or acoustic-gravity waves (AGWs) occur. Gravity wave theory predicts that the ion convergence node, without other influences, coincides with a temperature maximum for a westward propagating wave. In this case, the ion layer coincides with the temperature maximum which results in a higher sodium concentration at or near the ion layer height. This proposed temperature dependency can, for the tidal wind field, account for the observed correlation between sodium and ion column abundances and is supported by the average O2(0–1) rotational temperature determinations made at Arecibo. Specifically, we propose that the formation of SSLs is due to the temperature fluctuations induced by AGWs, or other wave processes, in conjunction with a background tidal wind system. Additionally, we argue that when an AGW propagates westward, the SSL coincides with an existing tidal ion layer or with a true sporadic-E layer which forms in the net wave field convergence zone. We also note that roughly the same processes may apply to the production of intense sporadic-E layers.
BibTeX:
@article{Zhou1993,
  author = {Q Zhou and J.D Mathews and C.A Tepley},
  title = {A proposed temperature dependent mechanism for the formation of sporadic sodium layers},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1993},
  volume = {55},
  number = {3},
  pages = {513-521},
  doi = {10.1016/0021-9169(93)90085-D}
}
Beatty TJ, Hostetler CA and Gardner CS (1992), "Lidar observations of gravity waves and their spectra near the mesopause and stratosphere at Arecibo", Journal of the Atmospheric Sciences. Vol. 49, pp. 477-496.
Abstract: The UIUC CEDAR Rayleigh/Na lidar was operated for approximately 160 h on 30 nights in January, March, and April 1989 at the Arecibo Observatory (18°N, 67°W) as part of the AIDA Act '89 Campaign. During this period 38 quasi-monochromatic gravity waves were observed in the stratopause region (25-55 km) and 62 waves were observed in the mesopause region (80–105 km). The event rates in both regions are approximately half those observed at the midlatitude site of Urbana. The characteristics of the waves in both regions are similar. Measured vertical wavelengths range from 1.1 to 17 km, vertical phase velocities from -6 to -270 cm s-1, observed periods from 5 min to 65 h, and amplitudes (relative atmospheric density variations) 0.4% to 17%. The wave amplitudes in the stratopause region are on average half the values for waves in the mesopause region with similar periods and vertical wavelengths. Vertical wavenumber spectra of density perturbations in both regions exhibit power-law dependencies with slopes near -3. The magnitudes of the spectra in the stratopause region are typically a factor of 5 to 10 times smaller than the magnitudes of the mesopause region spectra, which is in significant disagreement with the predictions of linear saturation theory. Temporal frequency spectra of density perturbations in the mesopause region also exhibit power-law dependencies with slopes between -1.5 and -2.0 (mean slope = 1.85 ± 0.38) for frequencies smaller than the Brunt-VÄisÄlÄ frequency and slopes near -3 for frequencies larger than the Brunt-VÄisÄlÄ frequency. The rms density perturbations averaged 1.2% in the stratopause region and 5.2% in the mesopause region. These results are compared with other radar and lidar observations.
BibTeX:
@article{Beatty1992,
  author = {Beatty, T J and Hostetler, C A and Gardner, C S},
  title = {Lidar observations of gravity waves and their spectra near the mesopause and stratosphere at Arecibo},
  journal = {Journal of the Atmospheric Sciences},
  year = {1992},
  volume = {49},
  pages = {477-496},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281992%29049%3C0477%3ALOOGWA%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1992)049}
}
Cheung PY, DuBois DF, Fukuchi T, Kawan K, Rose HA, Russell D, Tanikawa T and Wong AY (1992), "Investigation of strong Langmuir turbulence in ionospheric modification", Journal of Geophysical Research: Space Physics. Vol. 97(A7), pp. 10575-10600.
Abstract: Recent results in the search for strong Langmuir turbulence effects during ionospheric modification experiments performed at the Arecibo Observatory are presented. Indirect evidence of Langmuir wave collapse is obtained through the observation of theoretically predicted “caviton-type” enhanced plasma waves spectra using the 430 MHz incoherent radar at Arecibo. A typical spectrum consists of a “free-mode” peak with a frequency that is significantly higher than the heater frequency, and a broad “caviton continuum” with frequencies below the heater frequency. Free modes are freely propagating Langmuir waves radiated by collapsing cavitons during collapse. The generation and dynamics of these “free modes” will be discussed. Asymmetries between the frequency shifts and strengths of the upshifted and downshifted free-mode lines and their dependence on the time delay following the onset of heating are explained in terms of the radiation of free Langmuir modes by cavitons and the subsequent propagation of free modes down or up the density gradient. Experimental results are compared with theoretical predictions. Results on the transition of “caviton-type” plasma line spectra to the commonly observed “decay-type” spectra will also be presented.
BibTeX:
@article{Cheung1992,
  author = {Cheung, P. Y. and DuBois, D. F. and Fukuchi, T. and Kawan, K. and Rose, Harvey A. and Russell, David and Tanikawa, T. and Wong, A. Y.},
  title = {Investigation of strong Langmuir turbulence in ionospheric modification},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1992},
  volume = {97},
  number = {A7},
  pages = {10575-10600},
  url = {http://dx.doi.org/10.1029/92JA00645},
  doi = {10.1029/92JA00645}
}
Cho JYN, Kelley MC and Heinselman CJ (1992), "Enhancement of Thomson scatter by charged aerosols in the polar mesosphere: Measurements with a 1.29-GHz radar", Geophysical Research Letters. Vol. 19(11), pp. 1097-1100.
BibTeX:
@article{Cho1992,
  author = {Cho, John Y. N. and Kelley, Michael C. and Heinselman, Craig J.},
  title = {Enhancement of Thomson scatter by charged aerosols in the polar mesosphere: Measurements with a 1.29-GHz radar},
  journal = {Geophysical Research Letters},
  year = {1992},
  volume = {19},
  number = {11},
  pages = {1097-1100},
  doi = {10.1029/92GL01155}
}
Hagan ME, Barth CA, Tobiska WK, Manson AH, Vincent RA, Buonsanto MJ, Burnside RG and Wickwar VB (1992), "Observations of upper atmospheric weather during solar minimum winter", Journal of Geophysical Research: Space Physics. Vol. 97(A4), pp. 4163-4176.
Abstract: We report on a wide variety of thermospheric and ionospheric observations from three consecutive January World Day campaign periods. Despite remarkably similar geophysical conditions characterizing the in situ forcing of the upper atmosphere during these solar minimum campaigns, we find significant variability in the observations of the ionosphere and thermosphere particularly at low latitudes in the American sector. In addition, we present further observational evidence of the unexpected exospheric temperature suppression at low latitudes initially reported by Hagan and Salah (1988). We discuss the lower and upper atmospheric coupling mechanisms of plausible importance to the interpretation of the observed thermospheric weather patterns. We report evidence that lower thermospheric [NO] (nitric oxide number density) and upward propagating atmospheric tides affected the thermospheric energy and momentum budgets during the campaign periods.
BibTeX:
@article{Hagan1992,
  author = {Hagan, M. E. and Barth, C. A. and Tobiska, W. K. and Manson, A. H. and Vincent, R. A. and Buonsanto, M. J. and Burnside, R. G. and Wickwar, V. B.},
  title = {Observations of upper atmospheric weather during solar minimum winter},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1992},
  volume = {97},
  number = {A4},
  pages = {4163-4176},
  url = {http://dx.doi.org/10.1029/91JA02130},
  doi = {10.1029/91JA02130}
}
Hansen JD, Morales GJ and Maggs JE (1992), "Large-scale HF-induced ionospheric modifications: Theory and modeling", Journal of Geophysical Research: Space Physics. Vol. 97(A11), pp. 17019-17032.
Abstract: A quantitative explanation is given for the observed (Hansen et al., 1992) large-scale (several kilometers in extent, gTe/Teo ~3, |gne|/neo ~ 25%) ionospheric modifications produced with the Arecibo HF heating facility. The process of nonlinear refraction is introduced and shown to be the key nonlinearity which makes possible the generation of the observed effects. Nonlinear refraction consists of the self-consistent reorientation of the HF reflection surface by heating-induced density modifications from a gravitationally aligned density gradient to a geometry with Vn perpendicular to the geomagnetic field. It causes the O mode radiation to refract across the geomagnetic field and results in focused heating along a narrow flux tube colinear with the modified reflection surface. A two-dimensional transport model that incorporates the effects of nonlinear refraction on F region modification is used to establish a detailed comparison with experimental results.
BibTeX:
@article{Hansen1992,
  author = {Hansen, J. D. and Morales, G. J. and Maggs, J. E.},
  title = {Large-scale HF-induced ionospheric modifications: Theory and modeling},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1992},
  volume = {97},
  number = {A11},
  pages = {17019-17032},
  url = {http://dx.doi.org/10.1029/92JA01603},
  doi = {10.1029/92JA01603}
}
Hines CO (1992), "Mesospheric VHF echoing layers - An interpretation of certain observations in terms of wave scavenging", Journal of Atmospheric and Terrestrial Physics. Vol. 54, pp. 1043-1049.
Abstract: Excellent observations, obtained with the MU radar in Japan, have exhibited the existence on one occasion of three layers of enhanced VHF echoing from the mesosphere in association with a nearly monochromatic gravity-wave wind profile there. The heights of the layers did not correlate with levels of minimum Richardson number induced by the wave, however, and so an interpretation in terms of wave instability was initially rejected. Here it is shown that smaller-scale waves, unresolved by the radar, would be expected to have been approaching critical layers, and so to have been rendered unstable, at just those heights from which the strongest echoes were obtained. The same mechanism - the scavenging of wave energy for the production of turbulence - is likely to be operative on other occasions and at other heights.
BibTeX:
@article{Hines1992,
  author = {Hines, C. O.},
  title = {Mesospheric VHF echoing layers - An interpretation of certain observations in terms of wave scavenging},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1992},
  volume = {54},
  pages = {1043-1049},
  url = {http://www.sciencedirect.com/science/article/pii/0021916992900702},
  doi = {10.1016/0021-9169(92)90070-2}
}
Kuo SP and Lee MC (1992), "A source mechanism producing HF-induced plasma lines (HFPLS) with up-shifted frequencies", Geophysical Research Letters. Vol. 19(3), pp. 249-252.
Abstract: A nonlinear scattering process has been analyzed as a source mechanism producing the frequency up-shifted HF-enhanced plasma lines (HFPLs) observed in the Arecibo ionospheric heating experiments. Parallelly propagating Langmuir waves generated by the parametric decay instability of the HF pump near the reflection height scatter off the background lower hybrid density fluctuations to produce the up-going and down-going Langmuir waves with frequencies greater than the pump frequency by several tens of KHz. The frequency up-shifted nature of excited Langmuir waves stems from the fact that the natural frequencies of the obliquely propagating Langmuir waves are higher than those of the parallelly propagating Langmuir waves at the same altitude. A physical picture is thus offered to explain how Langmuir waves with frequencies greater than the HF heater wave frequency can be produced in the heating experiments and be detected by incoherent radars as frequency up-shifted HFPLs. Since the considered scattering process occurs in a region near the reflection height, it explains why the frequency up-shifted HFPLs should originate from the altitude near the reflection height as observed. Moreover, the theory also shows that the amount of frequency up-shift is inversely proportional to the frequency of the HF heater and increases linearly with the electron temperature. The quantitative analysis of the theory shows a good agreement with the experimental results.
BibTeX:
@article{Kuo1992,
  author = {Kuo, S. P. and Lee, M. C.},
  title = {A source mechanism producing HF-induced plasma lines (HFPLS) with up-shifted frequencies},
  journal = {Geophysical Research Letters},
  year = {1992},
  volume = {19},
  number = {3},
  pages = {249-252},
  url = {http://dx.doi.org/10.1029/92GL00092},
  doi = {10.1029/92GL00092}
}
Muldrew DB (1992), "Initial duct growth determined from cold-start plasma-line data recorded at Arecibo", Geophysical Research Letters. Vol. 19(1), pp. 65-68.
Abstract: Recent high-resolution height observations of the HF-induced plasma line have been made by Djuth et al. [1990]. The plasma line is first observed after 3 ms very close to the HF-reflection height and not at the height expected from weak-turbulence theory in a uniformly varying ionosphere. Natural field-aligned ducts exist in the ionosphere. Those with a diameter of a few meters or more can trap Langmuir waves (L waves) generated by the parametric decay instability and propagating nearly parallel to the magnetic field B. The ponderomotive force of the trapped L waves near the highest HF interference maximum causes electrons to be expelled parallel to B and ions to be expelled perpendicular to B. The ion gyroradius is comparable to the smallest duct diameter that can trap L waves. Since it only takes a few milliseconds for the ions to move at their thermal velocity across the duct, the duct can grow in a few milliseconds to a level where L waves capable of backscattering the Arecibo radar can be trapped. Duct growth is eventually limited by Landau damping and/or escape of the ducted L waves. These control the lower-height limit of the plasma line and terminate the overshoot.
BibTeX:
@article{Muldrew1992,
  author = {Muldrew, D. B.},
  title = {Initial duct growth determined from cold-start plasma-line data recorded at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1992},
  volume = {19},
  number = {1},
  pages = {65-68},
  url = {http://dx.doi.org/10.1029/91GL02870},
  doi = {10.1029/91GL02870}
}
Rishbeth H and Lanchester B (1992), "Incoherent scatter observations of the E and F regions ", Planetary and Space Science . Vol. 40(2–3), pp. 355-372.
Abstract: This paper outlines the principles of the incoherent scatter technique and briefly reviews the ways in which it has been used to study the ionospheric E and F regions. Examples are given of the important scientific advances that have been made over the last thirty years.
BibTeX:
@article{Rishbeth1992,
  author = {H. Rishbeth and B.S. Lanchester},
  title = {Incoherent scatter observations of the E and F regions },
  journal = {Planetary and Space Science },
  year = {1992},
  volume = {40},
  number = {2–3},
  pages = {355-372},
  url = {http://www.sciencedirect.com/science/article/pii/003206339290069Z},
  doi = {10.1016/0032-0633(92)90069-Z}
}
Stocker AJ, Robinson TR and Jones TB (1992), "Observations of the effects of ionospheric heating on the amplitude of low-power diagnostic radio waves at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 97(A5), pp. 6315-6322.
Abstract: The effects of ionospheric heating on low-power diagnostic radio waves at Arecibo are reported. During O mode heating it was found that the signal strengths of the diagnostic waves were reduced by up to approximately 7 dB. The diagnostic signals are only significantly attenuated during heating at full power (effective radiated power of 80 MW). During X mode heating, no amplitude effects could be detected. The maximum attenuation of the diagnostic signals measured at Arecibo is lower than those typically observed at TromsÜ, which is consistent with the predictions of theory. These results are discussed in the context of theoretical calculations of the anomalous absorption due to mode coupling caused by small-scale field-aligned irregularities. From observations of the effects of heating on the amplitudes of several low-power diagnostics, the length of these irregularities along the geomagnetic field is estimated.
BibTeX:
@article{Stocker1992,
  author = {Stocker, A. J. and Robinson, T. R. and Jones, T. B.},
  title = {Observations of the effects of ionospheric heating on the amplitude of low-power diagnostic radio waves at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1992},
  volume = {97},
  number = {A5},
  pages = {6315-6322},
  url = {http://dx.doi.org/10.1029/92JA00146},
  doi = {10.1029/92JA00146}
}
RICHMOND AD (1991), "The Ionospheric Wind Dynamo", Journal of geomagnetism and geoelectricity. Vol. 43(Supplement1), pp. 433-440.
Abstract: This paper presents a brief review of recent work concerning the global Ionospheric wind dynamo, with a view toward helping to define some principal directions for future research. Remaining problem areas are identified as: more accurate determination of the distributions of ionospheric conductivities, especially in the highly variable F region; determination of the distributions of winds in the E region under all seasonal conditions, especially the tidal components; improved understanding of the mutual coupling effects among variations in conductivities, thermospheric winds, and electric fields and currents; and quantitative understanding of the mutual coupling processes acting between the magnetospheric and ionospheric dynamos and the changes in the ionospheric dynamo occurring during magnetic storms.
BibTeX:
@article{1991433,
  author = {A. D. RICHMOND},
  title = {The Ionospheric Wind Dynamo},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1991},
  volume = {43},
  number = {Supplement1},
  pages = {433-440},
  doi = {10.5636/jgg.43.Supplement1_433}
}
FESEN CG (1991), "Lower Atmosphere/Thermosphere/Ionosphere Coupling Due to Tides", Journal of geomagnetism and geoelectricity. Vol. 43(Supplement1), pp. 479-499.
Abstract: The study of middle atmosphere tides has progressed rapidly due to advances in both observations and theory. Mesospheric tidal measurements during ATMAP (Atmospheric Tides Middle Atmosphere Program) in particular have provided the means to begin addressing the detailed coupling between the lower and upper atmosphere due to tidal waves. The Lower Thermosphere Coupling Study (LTCS) is extending the domain of interest to the thermosphere. Some results of the first LTCS campaign during September 1987, encompassing observations from 14 instruments, are described. These include the derivation of an empirical model of the data set, a method to extrapolate mesosphere predictions and/or data sets into the 100-130km altitude region, and a means to derive boundary conditions for global thermospheric models which simulate the effects of upward propagating tides on the model solutions. The theoretical models exhibit encouraging agreement with the data, particularly for mid-and high latitudes. Surprisingly, worst agreement occurs for observations made at Arecibo, a low latitude site. This has been tentatively attributed to the neglect of electrodynamics in the model. The observations also suggest the presence of a strong (2, 3) mode during the LTCS-1 campaign, which appears unusual for an equinox period. Recent works which investigate the question of tidal set-up times and the effects of transients are briefly discussed. These topics are particularly relevant to discussion of LTCS-1 observations since the interval included two isolated periods of geomagnetic activity.
BibTeX:
@article{1991479,
  author = {C. G. FESEN},
  title = {Lower Atmosphere/Thermosphere/Ionosphere Coupling Due to Tides},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1991},
  volume = {43},
  number = {Supplement1},
  pages = {479-499},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/43/Supplement1/43_Supplement1_479/_article},
  doi = {10.5636/jgg.43.Supplement1_479}
}
Rottger J (1991), "MST Radar and Incoherent Scatter Radar Contributions to Studying the Middle Atmosphere", Journal of geomagnetism and geoelectricity. Vol. 43(Supplement2), pp. 563-596.
Abstract: We outline the development of Mesosphere-Stratosphere-Troposphere (MST) radar research of the middle atmosphere with special emphasis on coupling processes from above and below. The coupling from above is important in high-latitude auroral regions and we therefore include into our descriptions also the Incoherent Scatter (IS) radar observations used to study the lower thermosphere and ionosphere. The possibility of Joule heating of the mesosphere is discussed as well as transport processes and the influence of solar proton events on the mesosphere. A characterization of mesospheric VHF radar echoes is given and their relation to electron density changes discussed. Gravity wave velocity measurements with MST radars in the mesosphere and stratosphere are briefly presented, as well as profiles of the mean horizontal and vertical wind in the troposphere and stratosphere. It is discussed how ST radars could contribute to investigations of the polar stratosphere and the ozone variation. Also the fine structure of VHF ST radar echoes is considered in terms of a similar fine structure in temperature and ozone profiles. ST radars can also be used to study synoptic scale disturbances, troposphere-stratosphere transport by means of observations of tropopause foldings and mean vertical velocity. We finally point out how ST radars could be effectively implemented to study tropical waves and vertical transport between the troposphere and the stratosphere in the tropics during deep convection.
BibTeX:
@article{1991563,
  author = {Jurgen Rottger},
  title = {MST Radar and Incoherent Scatter Radar Contributions to Studying the Middle Atmosphere},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1991},
  volume = {43},
  number = {Supplement2},
  pages = {563-596},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/43/Supplement2/43_Supplement2_563/_article},
  doi = {10.5636/jgg.43.Supplement2_563}
}
Biondi MA, Meriwether JW, Fejer BG, Gonzalez SA and Hallenbeck DC (1991), "Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990", Journal of Geophysical Research: Space Physics. Vol. 96(A9), pp. 15917-15930.
Abstract: Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over ~2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the expected, underlying forcing and damping processes. For most of the years, at the winter solstice, there is a weak (<=100 m/s) transequatorial flow from the summer to the winter hemisphere in the early and the late night, with essentially zero velocities in between. At the equinoxes, an early-night poleward (southward) flow at solar minimum (1986) is replaced by an equatorward (northward) flow at solar maximum (1989–1990). The zonal flows are predominantly eastward throughout the night, except for the solar minimum equinoxes, where brief westward flows appear in the early and the late night. The peak eastward velocities increase toward solar maximum; at the winter solstice, they are ~100–130 m/s in 1983, 1984 and 1986, reaching~200 m/s in 1988, 1989 and 1990. The present equatorial thermospheric wind determinations agree in some respects with the satellite-data-based horizontal wind model HWM-87 and the vector spherical harmonic form of the thermospheric general circulation model. They also are generally consistent with earlier studies at Arecibo, Puerto Rico, and at Kwajalein, Marshall Islands, when compared at similar parts of the solar cycle.
BibTeX:
@article{Biondi1991,
  author = {Biondi, M. A. and Meriwether, J. W. and Fejer, B. G. and Gonzalez, S. A. and Hallenbeck, D. C.},
  title = {Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A9},
  pages = {15917-15930},
  doi = {10.1029/91JA01645}
}
Breen A and Williams P (1991), "The relationship between electron density and electron temperature under quiet conditions in the Auroral zone", Advances in Space Research. Vol. 11(10), pp. 167-170.
BibTeX:
@article{Breen1991,
  author = {A.R. Breen and P.J.S. Williams},
  title = {The relationship between electron density and electron temperature under quiet conditions in the Auroral zone},
  journal = {Advances in Space Research},
  year = {1991},
  volume = {11},
  number = {10},
  pages = {167-170},
  doi = {10.1016/0273-1177(91)90339-L}
}
Burnside R, Tepley C and Sulzer M (1991), "World Day observations at Arecibo: 1985 to 1989", Journal of Geophysical Research. Vol. 96(A3), pp. 3691-3710.
Abstract: In the past 5 years, simultaneous incoherent scatter and optical observations have been obtained at Arecibo, Puerto Rico, during fourteen World Day campaigns with an average duration of 3 or more days. Here we present the period average values of important F layer parameters such as the peak electron density and the height of the layer peak. We have compared our electron density measurements with those given by the international reference ionosphere and generally find a reasonable agreement. The meridional neutral wind velocity is calculated for a height of 300 km from the incoherent scatter measurements. The period average values of the vertical gradient in the meridional wind velocity is derived. A maximum positive gradient in this quantity and the vertical gradient in the vertical ion velocity are found to occur near to 0600 AST in most of the months we have examined. We find that these vertical gradients are some three times larger for solar cycle minimum conditions than they are at solar cycle maximum. This is a new result that, as far as we are aware, has not been reported before. The period average values of the southward and eastward ion velocities are also derived from the measured radar line-of-sight velocities and show no obvious solar cycle dependence. We have used an ion energy balance method to infer atomic oxygen densities and exospheric temperatures at Arecibo. The temperatures show a fair agreement with the mass spectrometer/incoherent scatter model. The neutral densities also agree fairly well for all the years up to 1989 but then are consistently less than those predicted by the model.
BibTeX:
@article{Burnside1991,
  author = {Burnside, RG and Tepley, CA and Sulzer, MP},
  title = {World Day observations at Arecibo: 1985 to 1989},
  journal = {Journal of Geophysical Research},
  year = {1991},
  volume = {96},
  number = {A3},
  pages = {3691-3710},
  url = {http://dx.doi.org/10.1029/90JA01983},
  doi = {10.1029/90ja01983}
}
Burnside RG, Tepley CA, Sulzer MP, Fuller-Rowell TJ, Torr DG and Roble RG (1991), "The neutral thermosphere at Arecibo during geomagnetic storms", Journal of Geophysical Research: Space Physics. Vol. 96(A2), pp. 1289-1301.
Abstract: Over the past five years, simultaneous incoherent scatter and optical observations have been obtained at Arecibo, Puerto Rico, during two major geomagnetic storms. The first storm we examine occurred during the World Day campaign of 12–16 January 1988, where on 14 January 1988, Kp values greater than 7 were recorded. An ion-energy balance calculation shows that atomic oxygen densities at a fixed height on 14 January 1988 were about twice as large as they were on the quiet days in this period. Simultaneous radar and Fabry-Perot interferometer observations were used to infer nighttime O densities on 14–15 January 1988 that were about twice as large as on adjacent quiet nights. On this night, unusually high westward ion velocities were observed at Arecibo. The Fabry-Perot measurements show that the normal eastward flow of the neutral wind was reversed on this night. The second storm we examine occurred on the night of 13–14 July 1985, when Kp values reached only 4+, but the ionosphere and thermosphere responded in a similar manner as they did in January 1988. On the nights of both 13–14 July 1985 and 14–15 January 1988, the electron densities observed at Arecibo were significantly higher than they were on nearby geomagnetically quiet nights. These results indicate that major storm effects in thermospheric winds and composition propagate to low latitudes and have a pronounced effect on the ionospheric structure over Arecibo.
BibTeX:
@article{Burnside1991a,
  author = {Burnside, R. G. and Tepley, C. A. and Sulzer, M. P. and Fuller-Rowell, T. J. and Torr, D. G. and Roble, R. G.},
  title = {The neutral thermosphere at Arecibo during geomagnetic storms},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A2},
  pages = {1289-1301},
  url = {http://dx.doi.org/10.1029/90JA01595},
  doi = {10.1029/90JA01595}
}
Fejer BG, de Paula ER, Gonzalez SA and Woodman RF (1991), "Average vertical and zonal F region plasma drifts over Jicamarca", Journal of Geophysical Research: Space Physics. Vol. 96(A8), pp. 13901-13906.
Abstract: The seasonal averages of the equatorial F region vertical and zonal plasma drifts are determined using extensive incoherent scatter radar observations from Jicamarca during 1968–1988. The late afternoon and nighttime vertical and zonal drifts are strongly dependent on the 10.7-cm solar flux. We show that the evening prereversal enhancement of vertical drifts increases linearly with solar flux during equinox but tends to saturate for large fluxes during southern hemisphere winter. We examine in detail, for the first time, the seasonal variation of the zonal plasma drifts and their dependence on solar flux and magnetic activity. The seasonal effects on the zonal drifts are most pronounced in the midnight-morning sector. The nighttime eastward drifts increase with solar flux for all seasons but decrease slightly with magnetic activity. The daytime westward drifts are essentially independent of season, solar cycle, and magnetic activity.
BibTeX:
@article{Fejer1991,
  author = {Fejer, B. G. and de Paula, E. R. and Gonzalez, S. A. and Woodman, R. F.},
  title = {Average vertical and zonal F region plasma drifts over Jicamarca},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A8},
  pages = {13901-13906},
  url = {http://dx.doi.org/10.1029/91JA01171},
  doi = {10.1029/91JA01171}
}
Fejer JA, Sulzer MP and Djuth FT (1991), "Height dependence of the observed spectrum of radar backscatter from HF-induced ionospheric Langmuir turbulence", Journal of Geophysical Research: Space Physics. Vol. 96(A9), pp. 15985-16008.
Abstract: Observations of the spectrum of 430-MHz radar backscatter from HF-induced Langmuir turbulence with height discrimination are described. During very stable ionospheric conditions under which the height of the below-threshold backscatter spectrum had changed by less than 300 m during a 7-min period, a 20-s-long temporary increase in the HF power from 3 MW ERP to 38 MW equivalent radiated HF power resulted in subsequent strong above-threshold spectra extending to heights up to 1200 m greater than the height of the below-threshold spectrum for more than a minute. The generation of irregularities in the plasma density during the 20 s of enhanced HF power is suggested as a possible cause of this persistence of strong above-threshold spectra at greater heights. The initial temporal evolution of the backscatter spectrum from Langmuir turbulence after the start of HF transmissions was observed for different heights. The observational results are compared with the predictions of existing theories of Langmuir turbulence.
BibTeX:
@article{Fejer1991a,
  author = {Fejer, J. A. and Sulzer, M. P. and Djuth, F. T.},
  title = {Height dependence of the observed spectrum of radar backscatter from HF-induced ionospheric Langmuir turbulence},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A9},
  pages = {15985-16008},
  url = {http://dx.doi.org/10.1029/91JA00565},
  doi = {10.1029/91JA00565}
}
Getman VS, Mathews JD, Morton YT, Zhou Q and Roper RG (1991), "Bolide AIDA: Orbital and Physical Characteristics", International Conference on Asteroids, Comets, Meteors 1991. Vol. 765, pp. 73.
Abstract: The preliminary results of our investigation of Bolide AIDA, which was observed on April 8, 1989 at 0526UT from three locations in Puerto Rico, are given. The observations were made as part of the AIDA’89 (Arecibo Initiative in Dynamics of the Atmosphere) campaign which involved about 20 separate instruments. This array of instruments serendipitously, and perhaps uniquely, allowed observations of this bright bolide by six methods simultaneously-visually, by All-Sky camera, by video camera system, y CCD Infrared Imager, by imaging narrow band spectrometer (MORTI) and by IDI (Imaging Doppler Interferometer) radar – resulting in a variety of data. Preliminary calculations indicate that the Bolide entered the atmosphere on a step trajectory, about 33o from vertical, which was followed from 72km altitude and 20km.s velocity down to 27.5km altitude and 2-3km/s velocity. The time of occurrence, the radiant (alphar=189.3o;rR=-7.9o), and the orbit show that the bolide belongs to the chi-Virginid stream, which is connected with the Appolo Group asteroids. Towards the end of the observed trajectory the Bolide exploded into at least four large fragments which were observed by the All-Sky camera and the Video camera system.
BibTeX:
@article{Getman1991,
  author = {Getman, V. S. and Mathews, J. D. and Morton, Y. T. and Zhou, Q. and Roper, R. G.},
  title = {Bolide AIDA: Orbital and Physical Characteristics},
  journal = {International Conference on Asteroids, Comets, Meteors 1991},
  year = {1991},
  volume = {765},
  pages = {73},
  url = {http://adsabs.harvard.edu/full/1991LPICo.765Q..73G}
}
Hedin AE, Biondi MA, Burnside RG, Hernandez G, Johnson RM, Killeen TL, Mazaudier C, Meriwether JW, Salah JE, Sica RJ, Smith RW, Spencer NW, Wickwar VB and Virdi TS (1991), "Revised global model of thermosphere winds using satellite and ground-based observations", Journal of Geophysical Research: Space Physics. Vol. 96(A5), pp. 7657-7688.
Abstract: Thermospheric wind data obtained from the Atmosphere Explorer E and Dynamics Explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground-based incoherent scatter radar and Fabry-Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km. Comparison of the various data sets with the aid of the model shows in general remarkable agreement, particularly at mid and low latitudes. The ground-based data allow modeling of seasonal/diurnal variations, which are most distinct at mid latitudes. While solar activity variations are now included, they are found to be small and not always very clearly delineated by the current data. They are most obvious at the higher latitudes. The model describes the transition from predominately diurnal variations in the upper thermosphere to semidiurnal variations in the lower thermosphere and a transition from summer to winter flow above 140 km to winter to summer flow below. Significant altitude gradients in the wind are found to extend to 300 km at some local times and pose complications for interpretation of Fabry-Perot observations.
BibTeX:
@article{Hedin1991,
  author = {Hedin, A. E. and Biondi, M. A. and Burnside, R. G. and Hernandez, G. and Johnson, R. M. and Killeen, T. L. and Mazaudier, C. and Meriwether, J. W. and Salah, J. E. and Sica, R. J. and Smith, R. W. and Spencer, N. W. and Wickwar, V. B. and Virdi, T. S.},
  title = {Revised global model of thermosphere winds using satellite and ground-based observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A5},
  pages = {7657-7688},
  url = {http://dx.doi.org/10.1029/91JA00251},
  doi = {10.1029/91JA00251}
}
Hines CO (1991), "The Saturation of Gravity Waves in the Middle Atmosphere. Part II: Development Of Doppler-Spread Theory", Journal of the Atmospheric Sciences. Vol. 48, pp. 1361-1379.
Abstract: The irregular winds of the middle atmosphere are commonly attributed to an upwardly propagating system of atmospheric gravity waves. Their one-dimensional (in vertical wavenumber m) power spectrum has been reported to exhibit a nearly universal behavior in its “tail” region of large m: both the form (~m-3) and the intensity of the tail are approximately invariant with meteorological conditions, time, place and height. This universality is often described as resulting from “saturation” of the system, with the physical cause of saturation being left for separate identification and analysis.

Here the cause is attributed to nonlinear interaction between the waves of the full spectrum, most specifically to the advective nonlinearity of the Eulerian fluid-dynamic equations. This nonlinearity has the effect of Doppler shifting the local intrinsic frequency of any given wave in the wind field imposed by all waves. Only an approximation to its effects is sought here, the wind field of the full spectrum being taken to be horizontal, horizontally stratified and constant in time, but otherwise that field is taken to have the statistical characteristics that would be expected of a wave-induced spectrum, including a propensity for growth with height.

It is found that waves with relatively large vertical wavenumber m exceeding a characteristic value mc (comparable to or greater than N0/2ror, where N0 is buoyancy frequency and ror is rms wind speed) are substantially Doppler spread in vertical wavenumber, most particularly into a large-m tail. At sufficiently large m, the waves are taken to be obliterated by dissipative processes. The net effect is to leave a tail that will be universal and can be identified readily with the observed tail (subject to further approximation in the treatment of the wave obliteration).

If the tail extends to a sufficiently large m—a well defined value mMinst—the spectrum as a whole renders itself unstable. The length of the tail is then taken to be limited by the instability, any m values observed beyond mMinst being attributed to turbulence.

The implications of these conclusions are built into spectral models of the “modified Desaubies” form for future application to middle-atmosphere modeling.

The theory is backed by appeal to observations and is brought briefly into contact with related views in oceanographic studies.

The body of the paper ignores the Coriolis force and the contribution of vertical motions to the advective nonlinearity, but their effects are touched on in two Appendices. It also assumes, for the most part, azimuthal isotropy in the propagation of the waves, but the consequences of abandoning this assumption are outlined in a third Appendix.

BibTeX:
@article{Hines1991,
  author = {Hines, C O},
  title = {The Saturation of Gravity Waves in the Middle Atmosphere. Part II: Development Of Doppler-Spread Theory},
  journal = {Journal of the Atmospheric Sciences},
  year = {1991},
  volume = {48},
  pages = {1361-1379},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281991%29048%3C1361%3ATSOGWI%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1991)048}
}
Hines CO (1991), "The Saturation of Gravity Waves in the Middle Atmosphere. Part I - Critique of linear-instability theory", Journal of the Atmospheric Sciences. Vol. 48, pp. 1348-1385.
Abstract: The irregular winds of the middle atmosphere are commonly attributed to an upwardly propagating system of atmospheric gravity waves. Their one-dimensional (in vertical wavenumber m) power spectrum has been reported to exhibit a nearly universal behavior in its “tail” region of large m: both the form (m-3) and the intensity of the tail are approximately invariant with meteorological conditions, time, place and height. This universality is often described as resulting from “saturation” of the system, with the physical cause of saturation being left for separate identification and analysis.

Of current theories as to physical cause, the most fully developed and widely employed assumes that saturation results from linear instability: that the waves of the tail grow in amplitude with height (in response to the decrease of atmospheric density) until the system as a whole, or each portion of its tail, is rendered unstable and prevented from growing further. Initially the form and then the intensity of the tail are said to result from this process.

The arguments in favor of this view are questioned in the present paper and found wanting (though the claim of instability remains unchallenged and is even reinforced). The waves of the tail are then recognized as being subject to a strong wave–wave interaction arising from the Eulerian advective nonlinearity—from the Doppler shifts that can be imposed upon them by the larger-scale winds of the wave system—a fact recognized in the corresponding oceanographic literature for about a decade now.

In a companion paper, a rudimentary analytic approximation to the advective nonlinearity is introduced, and its consequences are shown to yield a spectral form and intensity quite similar to those obtained observationally. The linear instabilities (and some formulas) of the present paper are then invoked to establish the length, rather than the form and intensity, of the tail, at least below the turbopause.

BibTeX:
@article{Hines1991a,
  author = {Hines, C O},
  title = {The Saturation of Gravity Waves in the Middle Atmosphere. Part I - Critique of linear-instability theory},
  journal = {Journal of the Atmospheric Sciences},
  year = {1991},
  volume = {48},
  pages = {1348-1385},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281991%29048%3C1348%3ATSOGWI%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1991)048}
}
Hines CO (1991), "The Saturation of Gravity Waves in the Middle Atmosphere. Part III: Formation of the Turbopause and of Turbulent Layers Beneath It", Journal of the Atmospheric Sciences., June, 1991. Vol. 48(11), pp. 1380-1385.
Abstract: Vertically variable horizontal winds observd over Arecibo by to and Woodman, which were previously interpreted as a manifestation of inertia-gravity waves having intrinsic periods comparable to the local inertial period, are reinterpreted as quasi-stationary gravity waves of much shqrter intrinsic period, induced orographically by airflow over the island and mountains of Puerto Rico. The ellipticity of the Viated halograph is attributed to an effect of background wind shears in the presence of such waves. This new interpretation carries implicationsboth for the study of similar wind patterns elsewhere and for the reproducibility ofwind fields at Arecibo, where a natural laboratory for the study of mountain waves, of critical-layer interactions and of associated turbulence appears to be available.
BibTeX:
@article{Hines1991b,
  author = {Hines, C O},
  title = {The Saturation of Gravity Waves in the Middle Atmosphere. Part III: Formation of the Turbopause and of Turbulent Layers Beneath It},
  journal = {Journal of the Atmospheric Sciences},
  year = {1991},
  volume = {48},
  number = {11},
  pages = {1380-1385},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281991%29048%3C1380%3ATSOGWI%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1991)048}
}
Muldrew DB (1991), "Duct-model explanation of the broad component of plasma-line spectra observed at Arecibo", Geophysical Research Letters. Vol. 18(12), pp. 2289-2292.
Abstract: The plasma-line spectrum observed during on-off cycling of the HF heater at Arecibo contains a broad component extending about 50 kHz from the first decay line. Shortly after HF turn-on this spectrum can have a maximum intensity 10–20 kHz from the heater frequency (broad bump) or the intensity can decrease monotonically with frequency separation from the first decay line. One possibility is that Langmuir waves (L waves) generated by parametric-decay of the heater wave are trapped in small-scale field-aligned ducts and are responsible for the first decay line. The heater electromagnetic wave can also become ducted near reflection in large-scale field-aligned ducts. If the heater wave is not ducted near reflection, its electric field is very nearly parallel to the earth's magnetic field B. The L waves then have wavenormals restricted to a range of angles about B. When these L waves decay parametrically into other L waves that can be detected by the radar, a broad-bump spectrum results. If the heater wave becomes ducted near reflection (which is probable during spread-F conditions), its electric field can make a considerable angle to B near reflection and the unstable L waves can propagate at all angles to B (including perpendicular). When these L waves decay parametrically into other L waves that can be detected by the radar, a monotonic spectrum results.
BibTeX:
@article{Muldrew1991,
  author = {Muldrew, D. B.},
  title = {Duct-model explanation of the broad component of plasma-line spectra observed at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1991},
  volume = {18},
  number = {12},
  pages = {2289-2292},
  url = {http://dx.doi.org/10.1029/91GL02626},
  doi = {10.1029/91GL02626}
}
Richards PG, Torr DG and Miller KL (1991), "O+, H+, and He+ Densities from the 200–1600 km Altitude Ionosphere at Arecibo: A Comparison of Theory and Measurement", In Modeling Magnetospheric Plasma Processes. Vol. 62, pp. 167-171. GEOPHYSICAL MONOGRAPH SERIES.
Abstract: We have compared measured 0+, H+, and He+ densities over the altitude range 200–1600 km at Arecibo on February 10, 1972 with densities calculated by our comprehensive ionosphere-plasmasphere model. There is excellent agreement between measurement and model for all three ions, indicating that the theory of the major ion chemistry appears to be well understood. Comparison was also made between the model and measured electron and ion temperatures. There was good agreement between the model and the data for the ion temperature and at most altitudes for the electron temperature during the daytime. However, in the region of the peak electron density, the measured daytime temperature was much larger than the model temperature. The model electron temperatures did agree very well with the measured temperatures for similar thermospheric conditions in February 1977. At night, the measured electron and ion temperatures were higher than the modeled temperatures, which were close to the neutral temperature, indicating a larger plasmaspheric heat reservoir than predicted by the model.
BibTeX:
@inbook{Richards1991,
  author = {Richards, P. G. and Torr, D. G. and Miller, K. L.},
  editor = {American Geophysical Union},
  title = {O+, H+, and He+ Densities from the 200–1600 km Altitude Ionosphere at Arecibo: A Comparison of Theory and Measurement},
  booktitle = {Modeling Magnetospheric Plasma Processes},
  publisher = {GEOPHYSICAL MONOGRAPH SERIES},
  year = {1991},
  volume = {62},
  pages = {167-171},
  url = {http://dx.doi.org/10.1029/GM062p0167},
  doi = {10.1029/GM062p0167}
}
Salah JE, Johnson RM and Tepley CA (1991), "Coordinated incoherent scatter radar observations of the semidiurnal tide in the lower thermosphere", Journal of Geophysical Research: Space Physics. Vol. 96(A2), pp. 1071-1080.
BibTeX:
@article{Salah1991,
  author = {Salah, J. E. and Johnson, R. M. and Tepley, C. A.},
  title = {Coordinated incoherent scatter radar observations of the semidiurnal tide in the lower thermosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1991},
  volume = {96},
  number = {A2},
  pages = {1071-1080},
  doi = {10.1029/90JA01529}
}
Slnghal R (1991), "The effect of the electric field and neutral winds on E-region ion densities and conductivities at low latitudes", Journal of Atmospheric and Terrestrial Physics. Vol. 53(10), pp. 949-957.
BibTeX:
@article{Slnghal1991,
  author = {R.P Slnghal},
  title = {The effect of the electric field and neutral winds on E-region ion densities and conductivities at low latitudes},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1991},
  volume = {53},
  number = {10},
  pages = {949-957},
  doi = {10.1016/0021-9169(91)90006-S}
}
Tepley CA, Sargoytchev SI and Hines CO (1991), "Initial Doppler Rayleigh lidar results from Arecibo", Geophysical Research Letters. Vol. 18, pp. 167-170.
Abstract: We present the first results of the operation of a Rayleigh lidar from the Arecibo Observatory. The device consists of an injection seeded, frequency doubled, Nd:YAG laser coupled with a single etalon, Fabry-Perot interferometer in the receiver, the combination of which permits Doppler observations of the backscattered spectral emission from the mesosphere. The measured winds from our initial experiments show a great deal of variability on time scales that appear to be less than the hour that it takes to measure a wind profile with the present system.
BibTeX:
@article{Tepley1991,
  author = {Tepley, C A and Sargoytchev, S I and Hines, C O},
  title = {Initial Doppler Rayleigh lidar results from Arecibo},
  journal = {Geophysical Research Letters},
  year = {1991},
  volume = {18},
  pages = {167-170},
  url = {http://dx.doi.org/10.1029/90GL02670},
  doi = {10.1029/90gl02670}
}
Berkey JE, Richmond AD, Barnes RM, Gonzalez S and Tepley CA (1990), "Solar cycle variations in F region electrodynamic drifts at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 95(A4), pp. 4303-4306.
Abstract: Plasma drift measurements for the F region of the ionosphere have been made by the Arecibo incoherent scatter radar over the course of more than one solar cycle. The analysis of the data indicates that there are significant differences in the nighttime drifts between solar minimum and solar maximum. In general, these results agree qualitatively with results obtained through previous studies which have been done for incoherent scatter measurements from Jicamarca, Peru, as well as with some characteristics of model simulations.
BibTeX:
@article{Berkey1990,
  author = {Berkey, J. E. and Richmond, A. D. and Barnes, R. M. and Gonzalez, S. and Tepley, C. A.},
  title = {Solar cycle variations in F region electrodynamic drifts at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1990},
  volume = {95},
  number = {A4},
  pages = {4303-4306},
  url = {http://dx.doi.org/10.1029/JA095iA04p04303},
  doi = {10.1029/JA095iA04p04303}
}
Bilitza D and Hoegy W (1990), "Solar activity variation of ionospheric plasma temperatures", Advances in Space Research . Vol. 10(8), pp. 81-90.
BibTeX:
@article{Bilitza1990,
  author = {D. Bilitza and W.R. Hoegy},
  title = {Solar activity variation of ionospheric plasma temperatures},
  journal = {Advances in Space Research },
  year = {1990},
  volume = {10},
  number = {8},
  pages = {81-90},
  doi = {10.1016/0273-1177(90)90190-B}
}
Biondi MA, Meriwether JW, Fejer BG and Gonzalez SA (1990), "Seasonal variations in the equatorial thermospheric wind measured at Arequipa, Peru", Journal of Geophysical Research: Space Physics. Vol. 95(A8), pp. 12243-12250.
Abstract: Studies have been carried out at Arequipa, Peru, of the seasonal variations in the thermospheric winds at moderate solar flux levels and low geomagnetic activity. Fabry-Perot interferometer measurements of the Doppler shifts in the 630.0 nm nightglow emission line from March to August 1983 and from April to October 1988 have yielded monthly-average meridional winds that are nearly zero (<50 m/s) and possibly fluctuating in direction through much of the night but develop a southward flow at 50–100 m/s in the early and the late night from May onward. The average zonal winds are eastward throughout the night, reaching peak velocities before local midnight and then decreasing. The peak velocities increase to a maximum around the June solstice. The winds are generally stronger in 1988 than in 1983, even though the solar EUV fluxes are comparable for both years. Comparison of the present results with earlier satellite measurements, as embodied in the Horizontal Wind Model of Hedin et al., reveals generally satisfactory agreement at the equinox and June solstice, except for the June 1988 period. Killeen et al.'s vector spherical harmonic form of the NCAR Thermospheric General Circulation Model, calculated for similar solar flux levels, yields meridional and zonal wind variations which exhibit the same temporal behaviors but generally smaller values than the present measurements. The present wind patterns are also compared with those measured during the same years at Arecibo, Puerto Rico; one finds oppositely directed meridional flows and similar, eastward zonal flows at the two locations, as expected from a consideration of solar EUV heating as the principal driving force.
BibTeX:
@article{Biondi1990,
  author = {Biondi, M. A. and Meriwether, J. W. and Fejer, B. G. and Gonzalez, S. A.},
  title = {Seasonal variations in the equatorial thermospheric wind measured at Arequipa, Peru},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1990},
  volume = {95},
  number = {A8},
  pages = {12243-12250},
  url = {http://dx.doi.org/10.1029/JA095iA08p12243},
  doi = {10.1029/JA095iA08p12243}
}
Burnside R and Tepley C (1990), "Airglow intensities observed in the southern and northern hemispheres", Planetary and Space Science. Vol. 38(9), pp. 1161-1177.
Abstract: Meridian scanning observations of the intensities of the OI emissions at 630.0 and 557.7 nm were made with a tilting-filter photometer at Sutherland, South Africa, between 1973 and 1977. These intensities have been compared with the intensities observed more recently with a Fabry-Perot interferometer at Arecibo, Puerto Rico. At both stations, we find that post-midnight enhancements of the 630 nm intensity are more pronounced in the summer months. We also find at both stations that the intensity of the 558 nm emission has an equinoctial peak. We observe that the ratio between the 558 nm intensity to the North and to the South of Sutherland has an annual variation with the largest ratios being observed in the southern winter.
BibTeX:
@article{Burnside1990,
  author = {R.G. Burnside and C.A. Tepley},
  title = {Airglow intensities observed in the southern and northern hemispheres},
  journal = {Planetary and Space Science},
  year = {1990},
  volume = {38},
  number = {9},
  pages = {1161-1177},
  url = {http://www.sciencedirect.com/science/article/pii/003206339090024K},
  doi = {10.1016/0032-0633(90)90024-K}
}
Djuth FT, Sulzer MP and Elder JH (1990), "High resolution observations of HF-induced plasma waves in the ionosphere", Geophysical Research Letters. Vol. 17(11), pp. 1893-1896.
Abstract: Langmuir oscillations excited by a powerful, high-frequency (HF) radio wave reflecting in the F-region have been studied in detail with the 430 MHz radar at Arecibo Observatory, Puerto Rico. Exceptionally good altitude and temporal resolution made it possible to closely examine transient plasma phenomena and allowed very weak plasma features to be seen in the ionosphere. The observations reveal an unexpected richness of complex plasma structure. Langmuir turbulence detected with the 430 MHz radar often occupies an extended altitude interval, particularly during the “plasma line overshoot” and at late times following HF turn-on. In the late time plasma environment, multiple layers of Langmuir turbulence are often observed. In general, important distinctions can be made between the excitation of Langmuir oscillations in a “cold” background ionosphere and in an ionosphere “preconditioned” by prior HF transmissions. The greatest differences are evident in the altitude and range extent of the backscatter measured immediately after HF turn-on.
BibTeX:
@article{Djuth1990,
  author = {Djuth, F. T. and Sulzer, M. P. and Elder, J. H.},
  title = {High resolution observations of HF-induced plasma waves in the ionosphere},
  journal = {Geophysical Research Letters},
  year = {1990},
  volume = {17},
  number = {11},
  pages = {1893-1896},
  url = {http://dx.doi.org/10.1029/GL017i011p01893},
  doi = {10.1029/GL017i011p01893}
}
Fejer BG, Kelley MC, Senior C, de la Beaujardiere O, Holt JA, Tepley CA, Burnside R, Abdu MA, Sobral JHA, Woodman RF, Kamide Y and Lepping R (1990), "Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS Campaign", Journal of Geophysical Research: Space Physics. Vol. 95(A3), pp. 2367-2377.
Abstract: This paper examines in detail the electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17–19, 1984, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. We study the penetration of both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres. In the dusk sector, a large perturbation of the zonal equatorial electric field was observed in the absence of similar changes at low and middle latitudes in the same longitudinal sector. The observations in the postmidnight sector are used to compare the longitudinal variation of the zonal perturbation electric field with predictions made from global convection models. Our results show that the meridional electric field perturbations are considerably more attenuated with decreasing latitude than the zonal fluctuations. As a result, we conclude that variations in the meridional electric field at low latitudes are largely due to dynamo effects. These observations are used to show that the global convection models reproduce a number of characteristics of low-latitude and equatorial electric fields associated with changes in the polar cap potential drop. In addition, we highlight several areas where there is still substantial disagreement between the electric field data and the theoretical results.
BibTeX:
@article{Fejer1990,
  author = {Fejer, B. G. and Kelley, M. C. and Senior, C. and de la Beaujardiere, O. and Holt, J. A. and Tepley, C. A. and Burnside, R. and Abdu, M. A. and Sobral, J. H. A. and Woodman, R. F. and Kamide, Y. and Lepping, R.},
  title = {Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS Campaign},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1990},
  volume = {95},
  number = {A3},
  pages = {2367-2377},
  url = {http://dx.doi.org/10.1029/JA095iA03p02367},
  doi = {10.1029/JA095iA03p02367}
}
Hagen J (1990), "Noise Parameter Transformations for Three-Terminal Amplifiers", IEEE Transactions on Microwave Theory and Techniques. Vol. 38(3), pp. 319-321.
Abstract: The common-emitter noise parameters and z parameters for a transistor (or any three-terminal amplifier) are used to obtain the corresponding sets of noise parameters for the common-base and common-collector configurations. It is shown that the three configurations must have the same minimum noise measure. A practical example is presented to confirm this invariance. High-gain amplifiers with the minimum noise figure can be built with any of the three configurations of combinations thereof. The choice of configuration is determined by factors such as ease of stabilization or bandwidth
BibTeX:
@article{Hagen1990,
  author = {Hagen, J.B.},
  title = {Noise Parameter Transformations for Three-Terminal Amplifiers},
  journal = {IEEE Transactions on Microwave Theory and Techniques},
  year = {1990},
  volume = {38},
  number = {3},
  pages = {319-321},
  doi = {10.1109/22.45351}
}
Huuskonen A and Turunen T (1990), "Observations of D- and E-region stratifications with incoherent scatter radar", Advances in Space Research . Vol. 10(10), pp. 93-100.
BibTeX:
@article{Huuskonen199093,
  author = {A. Huuskonen and T. Turunen},
  title = {Observations of D- and E-region stratifications with incoherent scatter radar},
  journal = {Advances in Space Research },
  year = {1990},
  volume = {10},
  number = {10},
  pages = {93-100},
  url = {http://www.sciencedirect.com/science/article/pii/027311779090014Q},
  doi = {10.1016/0273-1177(90)90014-Q}
}
Ierkic HM, Woodman RF and Perillat P (1990), "Ultrahigh vertical resolution radar measurements in the lower stratosphere at Arecibo", Radio Science. Vol. 25(5), pp. 941-952.
Abstract: We report on heretofore unprecedented observations of the turbulent layers in the lower stratosphere using the Arecibo 2380-MHz radar. Spectral profiles with about 20 m height and 15 s time resolutions at altitudes in the range 16–19 km are used to parameterize relevant characteristics of the turbulence, namely vertical widths, distributions, lifetimes, and cutoff height. Our measurements validate previous deconvolved estimates and are free from contaminating factors like shear or beam broadening and partial reflections. Some theoretical predictions are verified, in particular those relating to the height of cutoff and the outer scale of the turbulence. We demonstrate the excellent capabilities of the instrument with observations of wave driven oscillatory displacements of thin turbulence structures near the tropopause. In these circumstances and because of the vertical resolution achieved, it is more direct to describe the inherent variability of spectral features following the vertical displacements of the layers rather than at a fixed height.
BibTeX:
@article{Ierkic1990,
  author = {Ierkic, H. M. and Woodman, R. F. and Perillat, P.},
  title = {Ultrahigh vertical resolution radar measurements in the lower stratosphere at Arecibo},
  journal = {Radio Science},
  year = {1990},
  volume = {25},
  number = {5},
  pages = {941-952},
  url = {http://dx.doi.org/10.1029/RS025i005p00941},
  doi = {10.1029/RS025i005p00941}
}
Isham B, Kofman W, Hagfors T, Nordling J, ThidÈ B, LaHoz C and Stubbe P (1990), "New phenomena observed by EISCAT during an RF ionospheric modification experiment", Radio Science. Vol. 25(3), pp. 251-262.
Abstract: An ionospheric HF-modification experiment was carried out near TromsÜ, Norway, using the Max-Planck-Institut fÝr Aeronomie (MPI) heating facility and the EISCAT 933-MHz incoherent scatter radar (ISR). The MPI heater was normally operated at 4.04 MHz and modulated 20-s on, 40-s off. The ISR observed waves propagating parallel to B0, and chirped as well as normal plasma line observations were performed. Heater-induced plasma lines were observed only in the first 10-s integration interval, indicating a strong overshoot. These lines are unusual in that multiple simultaneous lines were observed, normally originating within one kilometer of the critical region but sometimes from lower heights, and that the frequency of the most constant line is offset some 250 kHz from the heating frequency, with the other lines occurring at greater frequency offsets. The natural, photoelectron-enhanced plasma line was not observed; however, the background plasma was diagnosed via ion line observations and comparisons to chirped observations performed at EISCAT in May 1986 indicate that increased Landau damping may be responsible for both the strong induced-line overshoot and the lack of a distinct natural line. Finally, ion power profile observations show the existence of a topside enhanced ion line at the critical density corresponding to the heater frequency. We believe this is due to strong O to Z-mode coupling parallel to B0 and a low ƒ0F2.
BibTeX:
@article{Isham1990,
  author = {Isham, B. and Kofman, W. and Hagfors, T. and Nordling, J. and ThidÈ, B. and LaHoz, C. and Stubbe, P.},
  title = {New phenomena observed by EISCAT during an RF ionospheric modification experiment},
  journal = {Radio Science},
  year = {1990},
  volume = {25},
  number = {3},
  pages = {251-262},
  url = {http://dx.doi.org/10.1029/RS025i003p00251},
  doi = {10.1029/RS025i003p00251}
}
Mahajan K, Kohli R, Pandey V and Sethi N (1990), "Information about the E-region valley from incoherent scatter measurements", Advances in Space Research. Vol. 10(8), pp. 17-20.
BibTeX:
@article{Mahajan1990,
  author = {K.K. Mahajan and R. Kohli and V.K. Pandey and N.K. Sethi},
  title = {Information about the E-region valley from incoherent scatter measurements},
  journal = {Advances in Space Research},
  year = {1990},
  volume = {10},
  number = {8},
  pages = {17-20},
  doi = {10.1016/0273-1177(90)90179-4}
}
Mayr H, Harris I, Herrero F, Spencer N, Varosi F and Pesnell W (1990), "Thermospheric gravity waves: Observations and interpretation using the transfer function model (TFM)", Space Science Reviews. Vol. 54(3-4), pp. 297-375.
BibTeX:
@article{Mayr1990,
  author = {Mayr, H.G. and Harris, I. and Herrero, F.A. and Spencer, N.W. and Varosi, F. and Pesnell, W.D.},
  title = {Thermospheric gravity waves: Observations and interpretation using the transfer function model (TFM)},
  journal = {Space Science Reviews},
  year = {1990},
  volume = {54},
  number = {3-4},
  pages = {297-375},
  doi = {10.1007/BF00177800}
}
Noble ST and Djuth FT (1990), "Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 95(A9), pp. 15195-15207.
Abstract: Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). These measurements were made with the high-power HF facility located near the Arecibo Observatory, Arecibo, Puerto Rico. The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was designed to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at ?70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area.
BibTeX:
@article{Noble1990,
  author = {Noble, S. T. and Djuth, F. T.},
  title = {Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1990},
  volume = {95},
  number = {A9},
  pages = {15195-15207},
  url = {http://dx.doi.org/10.1029/JA095iA09p15195},
  doi = {10.1029/JA095iA09p15195}
}
Thide B (1990), "Stimulated Scattering of Large Amplitude Waves in the Ionosphere: Experimental Results", Physica Scripta. Vol. T30, pp. 170-180.
Abstract: A powerful high-frequency radio wave propagating through the ionospheric plasma acts as a pump and excites parametric and other nonlinear processes. These processes can be observed by using diagnostic Thomson scatter radars to probe the pump-enhanced plasma turbulence or by analysing the scattered pump wave directly. Such analyses performed at high and low latitudes (Tromso, Norway and Arecibo, Puerto Rico) have shown that the physics is extremely complicated and that old theory cannot satisfactorily explain all results. These experiments can shed new light on nonlinear plasma physics in general but may also provide means for diagnosing the near-Earth plasma and for testing theories of astrophysical plasma processes.
BibTeX:
@article{Thide1990,
  author = {Bo Thide},
  title = {Stimulated Scattering of Large Amplitude Waves in the Ionosphere: Experimental Results},
  journal = {Physica Scripta},
  year = {1990},
  volume = {T30},
  pages = {170-180},
  url = {http://www.physics.irfu.se/Publications/Articles/Thide:PS:1990.pdf}
}
Zinn J, Sutherland CD and Ganguly S (1990), "The solar flare of August 18, 1979: Incoherent scatter radar data and photochemical model comparisons", Journal of Geophysical Research: Atmospheres. Vol. 95(D10), pp. 16705-16718.
Abstract: Measurements of electron density at seven D region altitudes were made with the Arecibo radar during a class X solar flare on August 18, 1979. Measurements of solar X ray fluxes during the same period were available from the GOES 2 satellite (0.5-4 å and 1-8 å) and from ISEE 3 (in four bands between 26 and 400 keV). From the X ray flux data we computed ionization rates in the D region and the associated chemical changes, using a coupled atmospheric chemistry and diffusion model (with 997 chemical reactions and 19 vertical levels). The computed electron densities matched the data quite well after we had adjusted the rate coefficients of three reactions, namely, O-2 + O2(1D) -- e + O2 + O2, O+2 + O2 + M -- O+4 + M, and O+4 + O -- O+2 + O3. We also discuss the hierarchies among the many flare-induced chemical reactions in two altitude ranges within the D region and the possible effects of two separate isomeric forms of O+4.
BibTeX:
@article{Zinn1990,
  author = {Zinn, John and Sutherland, C. D. and Ganguly, Suman},
  title = {The solar flare of August 18, 1979: Incoherent scatter radar data and photochemical model comparisons},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1990},
  volume = {95},
  number = {D10},
  pages = {16705-16718},
  url = {http://dx.doi.org/10.1029/JD095iD10p16705},
  doi = {10.1029/JD095iD10p16705}
}
SARYO T, TAKEDA M, ARAKI T, SATO T, TSUDA T, FUKAO S and KATO S (1989), "Ion Drift Measured by MU Radar and Its Comparison with Geomagnetic Field Variation", Journal of geomagnetism and geoelectricity. Vol. 41(7), pp. 597-611.
Abstract: By using MU radar at Shigaraki, Japan, ion drift and the electron density profile in the F region were observed during two periods, September 17-18 and October 7-8, 1986. Between 23h LT and 24h LT on September 17, a clear difference was found between the electron density profiles observed by the eastward and westward beams, which may be caused by a wave propagated from east to west. A clear negative correlation between the perpendicular northward (V?) and parallel (V//) component of the velocity, which is caused by the F region dynamo action, was found as observed at Arecibo. The daily variation pattern of V? was similar to that observed at Arecibo, especially in the daytime, but that of the eastward drift was different. Geomagnetic field variations were estimated by using a drift velocity and conductivities deduced from the IRI 79 model (IRI 79, 1981) compared to observations at Miyazu, approximately 110km northwest of the radar site. Discordance between the estimated and observed field variations was concluded to be caused by ionospheric winds, which contribute to the generation of the geomagnetic Sq field through the induced electric field.
BibTeX:
@article{1989597,
  author = {T. SARYO and M. TAKEDA and T. ARAKI and T. SATO and T. TSUDA and S. FUKAO and S. KATO},
  title = {Ion Drift Measured by MU Radar and Its Comparison with Geomagnetic Field Variation},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1989},
  volume = {41},
  number = {7},
  pages = {597-611},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/41/7/41_7_597/_article},
  doi = {10.5636/jgg.41.597}
}
Beatty TJ, Collins RL, Gardner CS, Hostetler CA, Sechrist CF and Tepley CA (1989), "Simultaneous radar and lidar observations of sporadic E and Na layers at Arecibo", Geophysical Research Letters. Vol. 16(9), pp. 1019-1022.
Abstract: During the early morning of January 16, 1989 the Arecibo 430 MHz incoherent scatter radar and the University of Illinois CEDAR Na lidar were operated simultaneously for several hours at the Arecibo Observatory, Puerto Rico (18°N, 67°W). At approximately 0425 LST a sporadic E (Es) layer began forming near 101 km altitude and moved steadily downward reaching an altitude of 99 km by 0500 LST. The electron abundance of the Es layer increased rapidly from approximately 3â109 cm?2 at 0510 LST to approximately 6â109 cm?2 by 0530 LST. During this same time period a sporadic Na (Nas) layer formed at the same altitude as the Es layer. Both the Es and Nas layers moved upwards together between 0530 and 0600 LST before dissipating at an altitude of 101 km. The high correlation between the altitude and abundance variations of the two layers strongly suggests that the Nas layer formation is related to the Es layer and may involve Na cluster ion chemistry.
BibTeX:
@article{Beatty1989,
  author = {Beatty, Timothy J. and Collins, Richard L. and Gardner, Chester S. and Hostetler, Chris A. and Sechrist, Chalmers F. and Tepley, Craig A.},
  title = {Simultaneous radar and lidar observations of sporadic E and Na layers at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1989},
  volume = {16},
  number = {9},
  pages = {1019-1022},
  url = {http://dx.doi.org/10.1029/GL016i009p01019},
  doi = {10.1029/GL016i009p01019}
}
Bernhardt PA, Duncan LM and Tepley CA (1989), "Heater-induced cavities as optical tracers of plasma drifts", Journal of Geophysical Research: Space Physics. Vol. 94(A6), pp. 7003-7010.
Abstract: A new technique is used to measure F region plasma drifts at night. The technique involves observing the motion of density cavities generated by high-power radio waves in the ionosphere. The airglow signature of the cavities is recorded and analyzed with a ground-based, low-light-level imaging system. The heater-induced cavity optical tracer method is capable of providing velocity information with an error less than 1 m/s and a time resolution better than 60 s.
BibTeX:
@article{Bernhardt1989,
  author = {Bernhardt, Paul A. and Duncan, L. M. and Tepley, C. A.},
  title = {Heater-induced cavities as optical tracers of plasma drifts},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1989},
  volume = {94},
  number = {A6},
  pages = {7003-7010},
  doi = {10.1029/JA094iA06p07003}
}
Bernhardt PA, Tepley CA and Duncan LM (1989), "Airglow enhancements associated with plasma cavities formed during Ionospheric Heating Experiments", Journal of Geophysical Research: Space Physics. Vol. 94(A7), pp. 9071-9092.
Abstract: Optical measurements made at the Arecibo Observatory during the 1987 heating campaign showed large temporal and spatial variations in 630.0-nm airglow enhancements during times of continuous power transmissions of high-power radio waves. Photometric data displayed fluctuations of 60 R or more in the red-line (630.0 nm) emission from atomic oxygen. These fluctuations were associated with heater-induced cavities which drifted and evolved in the modified ionosphere. Data from the Arecibo incoherent scatter radar were used in conjunction with airglow images to provide a physical interpretation of the modification process. Electrons were accelerated by large amplitude Langmuir waves excited by parametric decay instabilities occurring near the wave reflection points inside the density cavities. Inelastic collisions with oxygen atoms produced excited states which yielded enhanced 630.0-nm and 557.7-nm emissions. A numerical model has been used to relate the enhanced airglow intensities to the energy spectrum of the accelerated electrons. The measured airglow could have been produced by an isotropic source at 340 km altitude that accelerated 0.01% of the ambient electrons into a suprathermal Maxwellian distribution with a temperature of 2.05 eV. Experimental and theoretical studies suggest that airglow clouds were directly coupled to plasma density cavities because (1) these cavities trapped the HF radio beam and (2) electrons accelerated out into regions of reduced plasma concentration were less effectively thermalized and, consequently, were more effective for collisional excitation of neutral species.
BibTeX:
@article{Bernhardt1989a,
  author = {Bernhardt, P. A. and Tepley, C. A. and Duncan, L. M.},
  title = {Airglow enhancements associated with plasma cavities formed during Ionospheric Heating Experiments},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1989},
  volume = {94},
  number = {A7},
  pages = {9071-9092},
  doi = {10.1029/JA094iA07p09071}
}
Burnside RG and Tepley CA (1989), "Optical observations of thermospheric neutral winds at Arecibo between 1980 and 1987", Journal of Geophysical Research: Space Physics. Vol. 94(A3), pp. 2711-2716.
Abstract: Since 1980, optical observations of nighttime thermospheric winds have been made using a Fabry-Perot interferometer at the Arecibo Observatory, Puerto Rico. High-resolution spectra of the O(¹D) airglow emission at 630.0 nm are obtained by observing at eight equally spaced azimuth positions and a fixed zenith angle of 60°. The neutral wind field is inferred by assuming that each component of the wind velocity vector may be expanded in a linear Taylor expansion about a point directly above the observatory. Both the zonal and meridional components of the thermospheric wind field are observed to have well-defined seasonal and nocturnal variations. For each year between 1980 and 1987, eastward flow was observed in the evening hours, with an average peak velocity of about 100 m s?1 near 2200 AST. In the winter months, the zonal wind generally remains eastward throughout the night. However, in summer, a reversal to westward flow is usually observed after local midnight. In the meridional direction, the largest equatorward velocities are observed in summer. A reduction (or reversal) in the meridional wind velocity is most often observed after midnight in the summer and equinoctial months. We find that the nocturnal and seasonal variations in the neutral wind field at Arecibo are remarkably unaffected by changes in the solar cycle.
BibTeX:
@article{Burnside1989,
  author = {Burnside, R. G. and Tepley, C. A.},
  title = {Optical observations of thermospheric neutral winds at Arecibo between 1980 and 1987},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1989},
  volume = {94},
  number = {A3},
  pages = {2711-2716},
  url = {http://dx.doi.org/10.1029/JA094iA03p02711},
  doi = {10.1029/JA094iA03p02711}
}
Cheung PY, Wong AY, Tanikawa T, Santoru J, DuBois DF, Rose HA and Russell D (1989), "Short–time-scale evidence for strong Langmuir turbulence during hf heating of the ionosphere", Physical Review Letters. Vol. 62, pp. 2676-2679.
Abstract: Results of short-pulse, low–duty-cycle hf-heating experiments are shown to agree with predictions of a model of correlated, localized cavitons which undergo cycles of nucleation, collapse, and burnout. Predicted ‘‘free-mode’’ spectral features associated with the radiation of Langmuir waves from collapsing cavitons are observed. Single radar pulse data provide evidence that temporal correlations between caviton events are present at early times following the onset of heating.
BibTeX:
@article{Cheung1989,
  author = {Cheung, P. Y. and Wong, A. Y. and Tanikawa, T. and Santoru, J. and DuBois, D. F. and Rose, Harvey A. and Russell, David},
  title = {Short–time-scale evidence for strong Langmuir turbulence during hf heating of the ionosphere},
  journal = {Physical Review Letters},
  year = {1989},
  volume = {62},
  pages = {2676-2679},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.62.2676},
  doi = {10.1103/PhysRevLett.62.2676}
}
Cornish CR and Larsen MF (1989), "Observations of Low-Frequency Inertia-Gravity Waves in the Lower Stratosphere over Arecibo", Journal of the Atmospheric Sciences. Vol. 46(15), pp. 2428-2439.
Abstract: Observations of the horizontal wind in the subtropical upper troposphere and lower stratosphere were made with the 430-MHz radar located at Arecibo, Puerto Rico (18.4°N), in May 1982 and April 1983. Both sets of observations displayed a slowly varying, anticyclonically rotating, persistent structure in the wind field just above the tropopause, similar to what would be expected if the oscillations are associated with quasi-inertia period waves. A spectral analysis of the May 1982 data revealed that a wave with a period in the earth-fixed earth-fixed reference frame close to 26 h was present. Our calculations show that the intrinsic wave periods varied from 2.5 times the inertial frequency to zero at a critical level near 18-km altitude. The changes in phase between perturbation velocities perpendicular and parallel to the propagation direction were systematic below the height where the intrinsic frequency was equal to the inertial frequency but showed a complicated behavior between that height and the critical level. Hines has recently proposed an explanation of similar observations as being due to orographic waves with intrinsic periods that are short compared to the inertial period. Our analysis indicates discrepancies with his simple explanation, although the data show that the waves may have an orographic source but with the earth-fixed period near 24 h determined by the very regular diurnal fluctuation in the surface winds over Puerto Rico. Thus, the observed waves may be orographically generated but with intrinsic frequencies, determined by the 24-h earth-fixed period, small enough to require the use of the dispersion relations for inertia-gravity waves with Coriolis effect included in order to explain the characteristics of the observations.
BibTeX:
@article{Cornish1989,
  author = {Cornish, C R and Larsen, M F},
  title = {Observations of Low-Frequency Inertia-Gravity Waves in the Lower Stratosphere over Arecibo},
  journal = {Journal of the Atmospheric Sciences},
  year = {1989},
  volume = {46},
  number = {15},
  pages = {2428-2439},
  url = {http://dx.doi.org/10.1175/1520-0469(1989)046<2428:OOLFIG>2.0.CO;2}
}
Djuth FT (1989), "Response of the Arecibo ionosphere to large HF-induced electron temperature enhancements", Advances in Space Research. Vol. 9, pp. 123-131.
BibTeX:
@article{Djuth1989,
  author = {Djuth, F T},
  title = {Response of the Arecibo ionosphere to large HF-induced electron temperature enhancements},
  journal = {Advances in Space Research},
  year = {1989},
  volume = {9},
  pages = {123-131},
  doi = {10.1016/0273-1177(89)90350-5}
}
Fejer J, Djuth F, Ierkic H and Sulzer M (1989), "Simultaneous observations of the enhanced plasma line and of the reflected HF wave at Arecibo", Journal of Atmospheric and Terrestrial Physics . Vol. 51, pp. 721-725.
Abstract: A suitably devised pulsing sequence of the powerful HF transmissions radiated towards the ionosphere below the penetration frequency made it possible to separate the attenuation of the reflected HF wave due to thermal and to ponderomotive type parametric instabilities. The separation was possible on account of the different growth times of the thermal and ponderomotive type parametric instabilities. At the same time the power in the 430 MHz enhanced plasma line was recorded. The results show that previously accepted explanations of the overshoot in the 430 MHz enhanced plasma line for 5.3 MHz HF transmissions are invalid. A strong overshoot was observed but the attenuation of the powerful HF wave was too small to be observed. For 3.175 MHz HF transmissions substantial attenuation was observed on both time scales.
BibTeX:
@article{Fejer1989,
  author = {J.A. Fejer and F.T. Djuth and H.M. Ierkic and M.P. Sulzer},
  title = {Simultaneous observations of the enhanced plasma line and of the reflected HF wave at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1989},
  volume = {51},
  pages = {721-725},
  url = {http://www.sciencedirect.com/science/article/pii/0021916989900275},
  doi = {10.1016/0021-9169(89)90027-5}
}
Hagfors T and Isham B (1989), "Past applications and future uses of chirped ISR plasma line observations", Advances in Space Research . Vol. 9(5), pp. 143-152.
BibTeX:
@article{Hagfors1989,
  author = {T. Hagfors and B. Isham},
  title = {Past applications and future uses of chirped ISR plasma line observations},
  journal = {Advances in Space Research },
  year = {1989},
  volume = {9},
  number = {5},
  pages = {143-152},
  doi = {10.1016/0273-1177(89)90352-9}
}
Hines CO (1989), "Latitudinal variation of tidal dissipation and upward propagation", Planetary and Space Science . Vol. 37(6), pp. 669-683.
Abstract: In classical, non-dissipative atmospheric tidal theory, vertical and latitudinal variations of dependent variables are separable. This is no longer the case when dissipation is introduced, and various authors have responded with various methods of dealing with the problem. A new method is developed here, in which an individual tidal mode is followed upward into the dissipating regions by way of a latitudinally variable vertical wavenumber. This method appears to have conceptual and operational advantages, both analytical and numerical, though it, too, has its limitations. In an appendix, the method is sketched also in application to the effects of background zonal winds on tidal propagation.
BibTeX:
@article{Hines1989,
  author = {Colin O. Hines},
  title = {Latitudinal variation of tidal dissipation and upward propagation},
  journal = {Planetary and Space Science },
  year = {1989},
  volume = {37},
  number = {6},
  pages = {669-683},
  url = {http://www.sciencedirect.com/science/article/pii/0032063389900378},
  doi = {10.1016/0032-0633(89)90037-8}
}
Hines CO (1989), "Tropopausal Mountain Waves over Arecibo: A Case Study", Journal of the Atmospheric Sciences. Vol. 46(4), pp. 476-488.
Abstract: Vertically variable horizontal winds observd over Arecibo by to and Woodman, which were previously interpreted as a manifestation of inertia-gravity waves having intrinsic periods comparable to the local inertial period, are reinterpreted as quasi-stationary gravity waves of much shqrter intrinsic period, induced orographically by airflow over the island and mountains of Puerto Rico. The ellipticity of the Viated halograph is attributed to an effect of background wind shears in the presence of such waves. This new interpretation carries implicationsboth for the study of similar wind patterns elsewhere and for the reproducibility ofwind fields at Arecibo, where a natural laboratory for the study of mountain waves, of critical-layer interactions and of associated turbulence appears to be available.
BibTeX:
@article{Hines1989a,
  author = {Hines, C. O.},
  title = {Tropopausal Mountain Waves over Arecibo: A Case Study},
  journal = {Journal of the Atmospheric Sciences},
  year = {1989},
  volume = {46},
  number = {4},
  pages = {476-488},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281989%29046%3C0476%3ATMWOAA%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1989)046}
}
Kerr R, Bishop J, Tepley C, Atreya S, Cageao R, Cherchneff I and Donahue T (1989), "Ground-Based Measurements of O1D and the H2O Production Rate From Comets", Advances in Space Research. Vol. 9(3), pp. 181-190.
BibTeX:
@article{Kerr1989,
  author = {Kerr, RB and Bishop, J and Tepley, CA and Atreya, SK and Cageao, RP and Cherchneff, IM and Donahue, TM},
  title = {Ground-Based Measurements of O1D and the H2O Production Rate From Comets},
  journal = {Advances in Space Research},
  year = {1989},
  volume = {9},
  number = {3},
  pages = {181-190},
  doi = {10.1016/0273-1177(89)90259-7}
}
Kildal P-S and Skyttemyr SA (1989), "Diffraction analysis of a proposed dual-reflector feed for the spherical reflector antenna of the Arecibo Observatory", Radio Science. Vol. 24(5), pp. 601-617.
Abstract: A proposed dual-reflector feed for the spherical reflector antenna in Arecibo is presented. This is analyzed over a large frequency range: at the lower frequencies by physical optics (PO) integration, and at the higher ones by a geometrical optic (GO) ray tracing technique described in another work. The latter calculations are extended with the transition region theory (TRT) to include edge diffraction. The results clearly demonstrate the usefulness of the time efficient TRT method. However, they also show that PO integration is important, as this has detected an underillumination of the central region of the aperture. This effect is related to a similar problem with the line feeds, but can in the present case be reduced by moving the subreflectors away from the paraxial focus.
BibTeX:
@article{Kildal1989,
  author = {Kildal, Per-Simon and Skyttemyr, Svein Andreas},
  title = {Diffraction analysis of a proposed dual-reflector feed for the spherical reflector antenna of the Arecibo Observatory},
  journal = {Radio Science},
  year = {1989},
  volume = {24},
  number = {5},
  pages = {601-617},
  url = {http://dx.doi.org/10.1029/RS024i005p00601},
  doi = {10.1029/RS024i005p00601}
}
Noble ST, Gordon WE, Duncan LM and McCoy JE (1989), "HF sideband generation in the ionosphere", Radio Science. Vol. 24(3), pp. 265-269.
Abstract: The temporal development of sidebands excited near sunrise by two strong HF waves separated by a few hertz is presented. Sidebands are not observed before sunrise when the ionospheric critical frequency is less than the heater frequency. As the ionospheric density increases following sunrise and overdense conditions are established, strong sidebands emerge. Even though these results favor a mechanism which phase modulates the reflected HF wave over one which first downconverts the HF power to ULF before exciting sidebands, it is possible that either mechanism could at times contribute to sideband production.
BibTeX:
@article{Noble1989,
  author = {Noble, S. T. and Gordon, W. E. and Duncan, L. M. and McCoy, J. E.},
  title = {HF sideband generation in the ionosphere},
  journal = {Radio Science},
  year = {1989},
  volume = {24},
  number = {3},
  pages = {265-269},
  url = {http://dx.doi.org/10.1029/RS024i003p00265},
  doi = {10.1029/RS024i003p00265}
}
Sulzer MP, Ierkic HM and Fejer JA (1989), "Observational limitations on the role of Langmuir cavitons in ionospheric modification experiments at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 94(A6), pp. 6841-6854.
Abstract: Observations of the time dependence of the enhanced plasma line power during high power ionospheric modification experiments at Arecibo, with a resolution of 1 ms, sometimes showed 5–10 ms long pulses recurring very nearly periodically every 20–50 ms. Other observations of the slower variations of power at Arecibo show the gradual disappearance of the plasma line overshoot as the HF pulsing was changed from 0.5-s on 5.5-s off to 0.5-s on 19.5-s off, and its gradual reappearance as the pulsing was changed back to 0.5-s on, 5.5-s off. Observations of the height dependence of the enhanced plasma line spectrum were also made. They showed that the decay line with its cascade and the OTSI line all originated at the same narrow range of heights which observations by others showed to be near and just below the theoretical height of reflection of the pump wave rather than, as was previously believed, at the considerably lower height where the dispersion relation of the Langmuir waves detected by the radar is satisfied in the unperturbed medium. The possibility of interpretation of the observations in terms of existing theories is considered and the need for further theoretical and experimental work is pointed out.
BibTeX:
@article{Sulzer1989,
  author = {Sulzer, M. P. and Ierkic, H. M. and Fejer, J. A.},
  title = {Observational limitations on the role of Langmuir cavitons in ionospheric modification experiments at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1989},
  volume = {94},
  number = {A6},
  pages = {6841-6854},
  url = {http://dx.doi.org/10.1029/JA094iA06p06841},
  doi = {10.1029/JA094iA06p06841}
}
Sulzer MP (1989), "Recent incoherent scatter techniques", Advances in Space Research . Vol. 9(5), pp. 153-162.
Abstract: Incoherent scatter radar is used to probe the ionized medium with characteristic parameters that vary by many orders of magnitude. In some circumstances simple radar techniques provide adequate or even optimum results; in others, special techniques are necessary. Two problems must be simultaneously solved. First, range ambiguity must be eliminated, and second, the statistical errors in the data must be kept to an acceptable level. We briefly state the theory of radar pulse compression since some of the complicated techniques are easily understood by analogy with pulse compression. We review the seven frequency long pulse technique used at Arecibo, and show that pulse compression theory is useful in simplifying the World Day experiment. The coded long pulse and alternating codes techniques are two recent developements which make optimum use of the transmitter power in many circumstances. These are discussed in detail and an analogy is developed between these techniques and those used in pulse compression.
BibTeX:
@article{Sulzer1989a,
  author = {Michael P. Sulzer},
  title = {Recent incoherent scatter techniques},
  journal = {Advances in Space Research },
  year = {1989},
  volume = {9},
  number = {5},
  pages = {153-162},
  url = {http://www.sciencedirect.com/science/article/pii/0273117789903530},
  doi = {10.1016/0273-1177(89)90353-0}
}
Tepley CA and Kerr RB (1989), "Variations in the proton concentration and flux of the topside ionosphere at Arecibo during the September 1984 Equinox Transition Study", Journal of Geophysical Research: Space Physics. Vol. 94(A12), pp. 16977-16986.
Abstract: Analysis of incoherent scatter radar measurements at Arecibo routinely take into account the presence of light ions above an altitude of 400 km. Combined with field-aligned ion velocity observations it is possible to determine the diurnal variations of the proton flux. We find that the near-zero daytime proton outflow in the topside ionosphere during equinox is not generally balanced by a larger nighttime inflow, as appears to be the case for other ions such as O+. The proton flux and concentration does respond, however, to external influences such as disturbed magnetic conditions. One such isolated magnetic storm occurred during the day during the Equinox Transition Study, a World Day investigation in September 1984. We show the response to the storm of several measured topside parameters, in particular the proton concentration and its flux, where significant departures from their nominally zero conditions occurred.
BibTeX:
@article{Tepley1989,
  author = {Tepley, C. A. and Kerr, R. B.},
  title = {Variations in the proton concentration and flux of the topside ionosphere at Arecibo during the September 1984 Equinox Transition Study},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1989},
  volume = {94},
  number = {A12},
  pages = {16977-16986},
  url = {http://dx.doi.org/10.1029/JA094iA12p16977},
  doi = {10.1029/JA094iA12p16977}
}
ThidÈ B, Hedberg å, Fejer JA and Sulzer MP (1989), "First observations of stimulated electromagnetic emission at Arecibo", Geophysical Research Letters. Vol. 16(5), pp. 369-372.
Abstract: The first observations of HF heater stimulated electromagnetic emissions induced in the low-latitude ionospheric plasma above Arecibo, Puerto Rico, are reported. Many systematic spectral features of the emissions bear a close resemblance to those observed in ionospheric modification experiments in the auroral zone and scale in accordance with detailed theory. This proves that these sideband emissions are not dependent on specific geophysical conditions but are due to fundamental interaction processes in the ionospheric plasma. We also report the discovery of unique, short-lived HF sideband emissions that are less systematic than those observed previously and accompanied by a quenching of the HF enhanced plasma and ion lines in the Arecibo 430 MHz incoherent scatter radar spectra.
BibTeX:
@article{Thide1989,
  author = {ThidÈ, Bo and Hedberg, åke and Fejer, Jules A. and Sulzer, Michael P.},
  title = {First observations of stimulated electromagnetic emission at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1989},
  volume = {16},
  number = {5},
  pages = {369-372},
  url = {http://dx.doi.org/10.1029/GL016i005p00369},
  doi = {10.1029/GL016i005p00369}
}
Tsuda T, Inoue T, Kato S, Fukao S, Fritts DC and VanZandt TE (1989), "MST Radar Observations of a Saturated Gravity Wave Spectrum", Journal of the Atmospheric Sciences. Vol. 46, pp. 2440-2447.
Abstract: We present vertical wavenumber spectra of mesoscale wind fluctuations using data observed in the troposphere, lower stratosphere and mesosphere by the MU radar at 35°N in Japan in October 1986 and June 1987, as well as lower stratospheric spectra obtained by the Arecibo UHF radar at 18°N in Puerto Rico in June 1983. These spectra are much more homogeneous than previously available spectra since all of the data were observed by the same radar technique, the data in the different atmospheric regions were taken essentially simultaneously, and all of the spectra were analyzed using very similar methods. In the large-wavenumber ranges of the observed spectra, the asymptomatic slopes and amplitudes agree well with the saturated gravity wave spectral model developed by Dewan and Good (1986) and Smith et al. (1987), which has a slope of -3 and a spectral amplitude proportional to the buoyancy frequency squared. The good agreement between the model spectrum and the observed spectra from different altitudes, different reasons, and two different stations located at 35° and 18°N suggests that the model is essentially correct, in spite of the heuristic nature of some of its assumptions.

The spectral densities of the zonal and meridional components are similar at large wavenumbers, while the meridional spectrum has larger energy density at small wavenumbers where the spectrum is not saturated. The dominant vertical scales of the gravity wave field in the mesosphere, lower stratosphere, and troposphere are estimated to be>10 km, 2.2 to 3.3 km, and >=3.3 km in october and >=4.5 km in June, respectively, consistent with determinations from previous studies.

BibTeX:
@article{Tsuda1989,
  author = {T. Tsuda and T. Inoue and S. Kato and and S. Fukao and D. C. Fritts and T. E. VanZandt},
  title = {MST Radar Observations of a Saturated Gravity Wave Spectrum},
  journal = {Journal of the Atmospheric Sciences},
  year = {1989},
  volume = {46},
  pages = {2440-2447},
  url = {http://dx.doi.org/10.1175/1520-0469(1989)046<2440:MROOAS>2.0.CO;2}
}
Bernhardt P, Duncan LM, Tepley CA, Behnke RA and Sheerin JP (1988), "Spatial and temporal evolution of 630.0 nm airglow enhancement during ionospheric heating experiments", Advances in Space Research. Vol. 8, pp. 271-277.
BibTeX:
@article{Bernhardt1988,
  author = {Bernhardt, PA and Duncan, L M and Tepley, C A and Behnke, R A and Sheerin, J P},
  title = {Spatial and temporal evolution of 630.0 nm airglow enhancement during ionospheric heating experiments},
  journal = {Advances in Space Research},
  year = {1988},
  volume = {8},
  pages = {271-277},
  doi = {10.1016/0273-1177(88)90372-9}
}
Bernhardt PA, Swartz WE, Kelly MC, Sulzer MP and Noble ST (1988), "Spacelab 2 Upper Atmospheric Modification Experiment Over Arecibo, 2, Plasma dynamics", Astrophysical Letters and Communications. Vol. 27, pp. 183-198.
Abstract: Results are presented from an experiment performed on Spacelab 2 over Arecibo to study the neutral gas dynamics of supersonic flows in a rarefield atmosphere and to modify the plasma density by releasing chemically reactive vapors. Exhaust vapor was released at an altitude of 317 km, where the plasma density was 300,000/cu cm. Observations were made with high resolution incoherent scatter radar. A localized depletion formed in the ionosphere. The depletion fell and eventually disappeared within the bottomside F-region ionosphere. The dynamics of the evolution of the depletion are discussed. Optical and radar data are compared, setting an upper limit of 3 percent for the branching ratio to produce O(D-1) from dissociative recombination of CO(2+) and electrons.
BibTeX:
@article{Bernhardt1988a,
  author = {Bernhardt, P. A. and Swartz, W. E. and Kelly, M. C. and Sulzer, M. P. and Noble, S. T.},
  title = {Spacelab 2 Upper Atmospheric Modification Experiment Over Arecibo, 2, Plasma dynamics},
  journal = {Astrophysical Letters and Communications},
  year = {1988},
  volume = {27},
  pages = {183-198},
  url = {http://adsabs.harvard.edu/abs/1988ApL%26C..27..183B}
}
Bernhardt PA, Kashiwa BA, Tepley CA and Noble ST (1988), "Spacelab 2 Upper Atmospheric Modification Experiment Over Arecibo, 1, Neutral Gas Dynamics", Astrophysical Letters and Communications. Vol. 27, pp. 169-181.
Abstract: The Orbital Maneuvering Subsystem engines of the Space Shuttle were used to inject H2, CO2, H2O and other combustion products into the upper atmosphere over the Arecibo Observatory. Images of the airglow enhancements that resulted from chemical reactions between the exhaust gases and the F-layer plasma showed that the exhaust vapor trail came to rest 80 km downstream from the center of the burn. A computer simulation of the gas dynamics shows that the region of the burn was dominated by a 'snow plow' effect sweeping out a corridor in the atmosphere and collisionally heating the injected vapors.
BibTeX:
@article{Bernhardt1988b,
  author = {Bernhardt, P A and Kashiwa, B A and Tepley, C A and Noble, S T},
  title = {Spacelab 2 Upper Atmospheric Modification Experiment Over Arecibo, 1, Neutral Gas Dynamics},
  journal = {Astrophysical Letters and Communications},
  year = {1988},
  volume = {27},
  pages = {169-181},
  url = {http://adsabs.harvard.edu/abs/1988ApL%26C..27..169B}
}
Bernhardt P, Duncan L and Tepley C (1988), "Artificial airglow excited by high-power radio waves.", Science. Vol. 242(4881), pp. 1022-1027.
Abstract: High-power electromagnetic waves beamed into the ionosphere from ground-based transmitters illuminate the night sky with enhanced airglow. The recent development of a new intensified, charge coupled-device imager made it possible to record optical emissions during ionospheric heating. Clouds of enhanced airglow are associated with large-scale plasma density cavities that are generated by the heater beam. Trapping and focusing of electromagnetic waves in these cavities produces accelerated electrons that collisionally excite oxygen atoms, which emit light at visible wavelengths. Convection of plasma across magnetic field lines is the primary source for horizontal motion of the cavities and the airglow enhancements. During ionospheric heating experiments, quasi-cyclic formation, convection, dissipation and reappearance of the cavites comprise a major source of long-term variability in plasma densities during ionospheric heating experiments.
BibTeX:
@article{Bernhardt1988c,
  author = {Bernhardt, P.A. and Duncan, L.M. and Tepley, C.A.},
  title = {Artificial airglow excited by high-power radio waves.},
  journal = {Science},
  year = {1988},
  volume = {242},
  number = {4881},
  pages = {1022-1027},
  url = {http://www.sciencemag.org.sci-hub.org/content/242/4881/1022},
  doi = {10.1126/science.242.4881.1022}
}
Burnside RG, Sulzer MP and Walker JCG (1988), "Determination of thermospheric temperatures and neutral densities at Arecibo from the ion energy balance", Journal of Geophysical Research: Space Physics. Vol. 93(A8), pp. 8642-8650.
Abstract: We use incoherent scatter measurements of ion and electron temperature and electron density to infer exospheric neutral temperatures and thermospheric atomic oxygen densities from the ion energy balance equation. Measurements obtained at four periods in 1985 and 1986, during the recent solar cycle minimum, are examined. At all seasons, the MSIS-86 empirical model of the thermosphere is found to overestimate daytime exospheric temperatures at Arecibo by an average of about 50°K. We find that daytime concentrations of H+ are not negligible at Arecibo at solar cycle minimum. Unless the presence of light ions is accounted for when analyzing autocorrelation functions measured by the incoherent scatter technique, significant errors can be made in determining the ion temperature and inferring the exospheric temperature. Deduced atomic oxygen densities are in good agreement with the MSIS model if it is adjusted to match the observed neutral temperatures and the commonly used value of the O+-O collision cross section is increased by 70%.
BibTeX:
@article{Burnside1988,
  author = {Burnside, R. G. and Sulzer, M. P. and Walker, J. C. G.},
  title = {Determination of thermospheric temperatures and neutral densities at Arecibo from the ion energy balance},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1988},
  volume = {93},
  number = {A8},
  pages = {8642-8650},
  url = {http://dx.doi.org/10.1029/JA093iA08p08642},
  doi = {10.1029/JA093iA08p08642}
}
Carlson HC, Weber EJ, Block LP and Basu S (1988), "Satellite, airborne and radar observations of auroral arcs", Advances in Space Research . Vol. 8(9–10), pp. 49-58.
Abstract: Multipoint measurements are necessary to address many pressing problems in space physics. The combination of satellite, airborne, and ground-based platforms for in-situ and remote sensors is a powerful approach to meeting these needs. The AFGL Airborne Ionospheric Observatory (AIO) has solved problems in this manner by operating in concert with VIKING, DE-B, AE-E, POLAR BEAR, HiLat, DMSP, WIDEBAND, and other satellites, and with Sondrestromfjord, EISCAT, Millstone Hill, Arecibo, and Jicamarca incoherent scatter radars. The aircraft platform has “parked” in satellite orbital planes for up to five consecutive passes, “parked” in the dark moon auroral oval for hours tracing plasma flow through the cusp into the polar cap, and traced detailed plasma boundaries by flying “racetrack orbits” under persistent boundaries.

We illustrate here some of the potential of such a combination of sensor platforms by presenting findings associated with auroral arcs, polar cap F-region stable sun-aligned arcs, theta auroras, and other auroral features.

BibTeX:
@article{Carlson1988,
  author = {Herbert C. Carlson and Edward J. Weber and Lars P. Block and Sunanda Basu},
  title = {Satellite, airborne and radar observations of auroral arcs},
  journal = {Advances in Space Research },
  year = {1988},
  volume = {8},
  number = {9–10},
  pages = {49-58},
  url = {http://www.sciencedirect.com/science/article/pii/0273117788901111},
  doi = {10.1016/0273-1177(88)90111-1}
}
Cornish CR (1988), "Observations of vertical velocities in the tropical upper troposphere and lower stratosphere using the Arecibo 430-MHZ radar", Journal of Geophysical Research: Atmospheres. Vol. 93(D8), pp. 9419-9431.
Abstract: We report the first clear-air observations of vertical velocities in the tropical upper troposphere and lower stratosphere (8–22 km) using the Arecibo 430-MHz radar. Oscillations in the vertical velocity near the Brunt-VÄisÄlÄ period are observed in the lower stratosphere during the 12-hour observation period. Frequency power spectra from the vertical velocity time series show a slope between ?0.5 and ?1.0. Vertical wave number spectra computed from the height profiles of vertical velocities have slopes between ?1.0 and ?1.5. These observed slopes do not agree well with the slopes of +1/3 and ?2.5 for frequency and vertical wave number spectra, respectively, predicted by a universal gravity-wave spectrum model. The spectral power of wave number spectra of a radial beam directed 15° off-zenith is enhanced by an order of magnitude over the spectral power levels of the vertical beam. This enhancement suggests that other geophysical processes besides gravity waves are present in the horizontal flow. The steepening of the wave number spectrum of the off-vertical beam in the lower stratosphere to near ?2.0 is attributed to a quasi-inertial period wave, which was present in the horizontal flow during the observation period.
BibTeX:
@article{Cornish1988,
  author = {Cornish, C. R.},
  title = {Observations of vertical velocities in the tropical upper troposphere and lower stratosphere using the Arecibo 430-MHZ radar},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {1988},
  volume = {93},
  number = {D8},
  pages = {9419-9431},
  url = {http://dx.doi.org/10.1029/JD093iD08p09419},
  doi = {10.1029/JD093iD08p09419}
}
Djuth FT and Gonzales CA (1988), "Temporal evolution of the HF-enhanced plasma line in sporadic E", Journal of Geophysical Research: Space Physics. Vol. 93(A1), pp. 196-208.
Abstract: The high-power, high-frequency (HF) facility at Arecibo, Puerto Rico, has been used to study the excitation of Langmuir waves in mid-latitude sporadic E. Measurements of the temporal evolution of the so-called HF-enhanced plasma line (HFPL) were made using the Arecibo 430-MHz radar. After HF turn-on in the plasma the HFPL exhibits a rapid growth phase followed by a quick overshoot. During periods of strong HFPL excitation the e-folding growth time of the HFPL power is typically ~< 20 µs, and the total overshoot period is ~1 ms. On the basis of the current observations, mode conversion of the HF wave into Langmuir waves near HF reflection appears to be a promising mechanism for the production of Langmuir waves in sporadic E. Caviton formation at the critical layer is expected to accompany this process, and there is some evidence that the 430-MHz radar is probing the plasma in a region where density cavities of this nature form. While no specific explanation is offered for the HFPL overshoot, it appears that this phenomenon is fundamental to the Langmuir wave excitation process.
BibTeX:
@article{Djuth1988,
  author = {Djuth, F. T. and Gonzales, C. A.},
  title = {Temporal evolution of the HF-enhanced plasma line in sporadic E},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1988},
  volume = {93},
  number = {A1},
  pages = {196-208},
  url = {http://dx.doi.org/10.1029/JA093iA01p00196},
  doi = {10.1029/JA093iA01p00196}
}
Fejer JA (1988), "Physical Processes of Ionospheric heating Experiments", Advances in Space Research. Vol. 81(1), pp. 261-270.
BibTeX:
@article{Fejer1988,
  author = {Fejer, J A},
  title = {Physical Processes of Ionospheric heating Experiments},
  journal = {Advances in Space Research},
  year = {1988},
  volume = {81},
  number = {1},
  pages = {261-270},
  doi = {10.1016/0273-1177(88)90371-7}
}
Herrero F, Mayr H and Spencer N (1988), "Low latitude thermospheric meridional winds between 250 and 450 km altitude: AE-E satellite data", Journal of Atmospheric and Terrestrial Physics . Vol. 50, pp. 1001-1006.
Abstract: The daily variations of the meridional wind at ±18° latitude have been obtained for summer and winter between 1977 and 1979 using the in situ measurements from the Atmosphere Explorer-E (AE-E) satellite. The AE-E altitude increased from about 250 to about 450 km during this period, with solar activity increasing simultaneously. Data are presented at three altitudes, around 270, 350 and 440 km. It was possible to average the data to obtain the 24 h variations of the meridional wind simultaneously at northern and southern latitudes and thereby study the seasonal variation of the meridional wind in the altitude range covered. Two features are found showing significant seasonal variation: (a) a late afternoon maximum of the poleward wind occurring only in winter at 1800 LT at all three altitudes; (b) a night-time maximum in the equatorward wind—the summer equatorward wind abating earlier (near 2130 LT) and more rapidly than the winter wind (after 2300 LT). Furthermore, in summer the night-time wind reaches higher amplitudes than in winter. The night-time feature is consistent with the observed seasonal variation of the equatorial midnight temperature maximum, which occurs at or before midnight in summer and after midnight in winter, showing a stronger maximum in summer. The observed night-time abatement and seasonal variations in the night-time winds are in harmony with ground based observations at 18° latitude (Arecibo). The time difference found between summer and winter abatements of the night-time equatorward wind are in large part due to a difference between the phases of the summer and winter diurnal (fundamental) components, and diurnal amplitudes are larger in summer than in winter at all threee altitudes. However, the higher harmonics play an important role, their amplitudes being roughly 50% of the diurnal and in some instances larger. The 24 h variation is mainly diurnal at all altitudes in both summer and winter, except in winter around 2700 km altitude where the semi- and ter-diurnal components are approximately equal to or larger than the diurnal.
BibTeX:
@article{Herrero1988,
  author = {F.A. Herrero and H.G. Mayr and N.W. Spencer},
  title = {Low latitude thermospheric meridional winds between 250 and 450 km altitude: AE-E satellite data},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1988},
  volume = {50},
  pages = {1001-1006},
  url = {http://www.sciencedirect.com/science/article/pii/0021916988900876},
  doi = {10.1016/0021-9169(88)90087-6}
}
Hines CO (1988), "Generation of Turbulence by Atmospheric Gravity Waves", Journal of the Atmospheric Sciences. Vol. 45(7), pp. 1269-1278.
Abstract: The standard current criterion for the generation of turbulence by atmospheric gravity waves and for the associated limitation on wave growth is based upon the standard criterion for static instability of the unperturbed atmosphere, namely, that the vertical gradient of potential temperature be negative. This criterion fails to recognize that a slantwise static instability may be available in the presence of gravity waves and, if so, could be of importance. New criteria, involving estimated growth times, are developed here and reveal slantwise instability to be a likely mechanism of turbulence production. It is also found that the most favored axes for the development of the slantwise instability are quasi-horizontal, which suggests that the resultant turbulent motions may well be quasi-horizontal, at least at the energy-input portion of the turbulence spectrum.
BibTeX:
@article{Hines1988,
  author = {Hines, C. O.},
  title = {Generation of Turbulence by Atmospheric Gravity Waves},
  journal = {Journal of the Atmospheric Sciences},
  year = {1988},
  volume = {45},
  number = {7},
  pages = {1269-1278},
  url = {http://dx.doi.org/10.1175/1520-0469(1988)045<1269:GOTBAG>2.0.CO;2},
  doi = {10.1175/1520-0469(1988)045}
}
Hines CO (1988), "On Ray Paths in Mountain Waves", Journal of the Atmospheric Sciences. Vol. 45(2), pp. 323-326.
Abstract: In mountain-wave studies, specific formulae are not well known for paths of ascent of wave energy and momentum from their origins in mountainous terrain. Thew formulae are developed and presented here, along with their sometimes bizarre implications. They were sought as part of an ongoing study of mountain-wave parameterization for use in general circulation modeling, but are important in their own right as well, e.g., in simple problems such as finding the terrain responsible for certain banded clouds.
BibTeX:
@article{Hines1988a,
  author = {Hines, C. O.},
  title = {On Ray Paths in Mountain Waves},
  journal = {Journal of the Atmospheric Sciences},
  year = {1988},
  volume = {45},
  number = {2},
  pages = {323-326},
  url = {http://dx.doi.org/10.1175/1520-0469(1988)045<0323:ORPIMW>2.0.CO;2},
  doi = {10.1175/1520-0469(1988)045}
}
Hines CO (1988), "A Modeling of Atmospheric Gravity Waves and Wave Drag Generated by Isotropic and Anisotropic Terrain.", Journal of Atmospheric Sciences. Vol. 45(12), pp. 309-322.
Abstract: Momentum deposition by orographically generated atmospheric gravity waves has been incorporated into a general circulation model of the troposphere and lower stratosphere by McFarlane, using a parameterization of real terrain and the waves that terrain would generate. Similar modeling will no doubt follow for extension to greater heights, where the effects of momentum deposition are expected to be greater. MeFarlane's parameterization treated an upward flux of momentum directed into a single azimuth (namely, that opposed to the surface wind) and tacitly assumed a Boussinesq approximation and horizontally isotropic terrain. These limitations are probed here and, to some extent, removed.The analysis is generalized from the Boussinesq to the `incompressible' approximation, with consequences that can be important in some circumstances. It is found appropriate to represent the momentum flux from isotropic terrain by two azimuths rather than one, these two being at angles of 32.5° or more from the single azimuth previously chosen. On the other hand, it is found appropriate to represent the momentum flux from anisotropic terrain by a single azimuth, that opposing the wind component normal to the long axis of the terrain, the transition from `isotropic' to `anisotropic' occurring at a length/breadth ratio of about two. Anomalous effects introduced by plateaus are also examined, and arguments are presented for removing them somewhat arbitrarily because of associated blocking.
BibTeX:
@article{Hines1988b,
  author = {Hines, C. O.},
  title = {A Modeling of Atmospheric Gravity Waves and Wave Drag Generated by Isotropic and Anisotropic Terrain.},
  journal = {Journal of Atmospheric Sciences},
  year = {1988},
  volume = {45},
  number = {12},
  pages = {309-322},
  url = {http://dx.doi.org/10.1175/1520-0469(1988)045<0309:AMOAGW>2.0.CO;2},
  doi = {10.1175/1520-0469(1988)045}
}
Huang ZH (1988), "A theory for high-frequency electromagnetic sideband generation by two pump waves", Radio Science. Vol. 23(4), pp. 708-712.
Abstract: Sidebands on the high-frequency (HF) waves received from two transmitted waves separated by small frequency intervals were first observed in January 1984 at the Arecibo Observatory (Ganguly and Gordon, 1986). Papadopoulos proposed that the nonlinear mechanism for the HF sideband generation is a parametric decay of a high-frequency radio wave into a low-frequency compressional Alfven wave and a high-freqeuncy sideband (Papadopoulos et al., 1982). In 1984, Fejer proposed another nonlinear mechanism (phase modulation) for the HF sideband generation (Fejer et al., 1985; Huang and Fejer, 1987). A modulation index theory using the WKB approximation is proposed here, showing that the amplitude of the sidebands are related to (1) the incident HF power, (2) the HF frequency, (3) the temperature of the electrons, (4) the scale height of the ionosphere, and (5) the difference frequency of the two HF pump waves.
BibTeX:
@article{Huang1988,
  author = {Huang, Z. H.},
  title = {A theory for high-frequency electromagnetic sideband generation by two pump waves},
  journal = {Radio Science},
  year = {1988},
  volume = {23},
  number = {4},
  pages = {708-712},
  url = {http://dx.doi.org/10.1029/RS023i004p00708},
  doi = {10.1029/RS023i004p00708}
}
Kerr RB and Tepley CA (1988), "Ground-based measurements of exospheric hydrogen density", Geophysical Research Letters. Vol. 15(12), pp. 1329-1332.
BibTeX:
@article{Kerr1988,
  author = {Kerr, R. B. and Tepley, C. A.},
  title = {Ground-based measurements of exospheric hydrogen density},
  journal = {Geophysical Research Letters},
  year = {1988},
  volume = {15},
  number = {12},
  pages = {1329-1332},
  url = {http://dx.doi.org/10.1029/GL015i012p01329},
  doi = {10.1029/GL015i012p01329}
}
Kuo SP and Djuth FT (1988), "A thermal instability for the spread-F echoes from HF-heated ionosphere", Geophysical Research Letters. Vol. 15(12), pp. 1345-1348.
Abstract: A thermal instability is studied for the generation of large-scale field-aligned irregularities in the F-region of the ionosphere. These irregularities are then explained to be the cause of the spread-F traces in the ionograms recorded in the recent Arecibo heating experiments. The background plasma is assumed to have an elevated electron temperature and a localized heat source located near the HF reflection height. The elevated electron temperature is maintained by the heat source which is supplied by the HF heater. The dispersion relation of the instability is derived and analyzed for the threshold condition and the growth rate. The calculated growth time of the large-scale irregularities is consistent with the Arecibo observations when measured electron-to-ion temperature ratios in the range between 2 and 3 are used in the analysis.
BibTeX:
@article{Kuo1988,
  author = {Kuo, S. P. and Djuth, F. T.},
  title = {A thermal instability for the spread-F echoes from HF-heated ionosphere},
  journal = {Geophysical Research Letters},
  year = {1988},
  volume = {15},
  number = {12},
  pages = {1345-1348},
  url = {http://dx.doi.org/10.1029/GL015i012p01345},
  doi = {10.1029/GL015i012p01345}
}
Mathews JD, Breakall JK and Sulzer MP (1988), "The Moon as a calibration target of convenience for VHF-UHF radar systems", Radio Science. Vol. 23(1), pp. 1-12.
Abstract: Knowledge of the absolute, versus relative, performance characteristics of VHF and UHF radars used in geophysical applications is often important. We suggest that the Moon may form a convenient, easily tracked calibration target for many such radars. The lunar absolute radar scattering crosssection is large, reasonably well known (~7% of the visible disk) and is essentially wavelength independent over 6 m > lambda > 1 cm. The Arecibo 430-MHz radar system was calibrated using the Moon as the target. These measurements, which are discussed in detail, yielded cross sections of 4.0% and 4.6% for a special 6 W and the main 1.6-MW transmitters, respectively. We develop and present the radar equation appropriate to all total power calibration procedures including the Arecibo “worst case” calibration. We also discuss error levels, the necessity for averaging to obtain valid cross sections, and other practical difficulties associated with the technique.
BibTeX:
@article{Mathews1988,
  author = {Mathews, J. D. and Breakall, J. K. and Sulzer, M. P.},
  title = {The Moon as a calibration target of convenience for VHF-UHF radar systems},
  journal = {Radio Science},
  year = {1988},
  volume = {23},
  number = {1},
  pages = {1-12},
  url = {http://dx.doi.org/10.1029/RS023i001p00001},
  doi = {10.1029/RS023i001p00001}
}
Muldrew DB (1988), "Duct model explanation of the plasma line overshoot observed at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 93(A7), pp. 7598-7604.
Abstract: The plasma line overshoot, which is observed at Arecibo during ionospheric-modification experiments, can be explained by propagation of Langmuir waves (L waves) trapped in magnetic field-aligned ducts. The miniovershoot, i.e., the early phase of the overshoot, results from the growth of L waves to saturation within a few milliseconds of transmitter turn-on in ducts developed during previous transmitter-on cycles. The ponderomotive force of these trapped L waves causes the electron density in the duct to decrease rapidly from about 30 to 200 ms after transmitter turn-on. An increase in plasma line (PL) intensity is assumed to result from this density decrease and this corresponds to the start of the main overshoot. After a few hundred milliseconds heating of the electrons begins to cause a further slow decrease in density. The heating is due to collisional and collisionless damping of the L waves. After a few seconds the duct density becomes sufficiently low that collisionless damping of the L waves responsible for the PL becomes severe and the PL intensity decreases. The ponderomotive force is maintained by other trapped L waves. Once the transmitter has been turned off the duct at first decays rapidly due to the removal of the ponderomotive force and then more slowly (10 to tens of seconds) due to both parallel and inward radial (i.e., perpendicular to the magnetic field) diffusion of plasma. The duct model can explain nearly all the observed characteristics of the PL obseved at Arecibo; other theories and models cannot.
BibTeX:
@article{Muldrew1988,
  author = {Muldrew, D. B.},
  title = {Duct model explanation of the plasma line overshoot observed at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1988},
  volume = {93},
  number = {A7},
  pages = {7598-7604},
  url = {http://dx.doi.org/10.1029/JA093iA07p07598},
  doi = {10.1029/JA093iA07p07598}
}
Rastogi PK, Mathews JD, Ying W-P and RÆttger J (1988), "Simultaneous VHF and UHF radar observations of the mesosphere at Arecibo during a solar flare: A check on the gradient-mixing hypothesis", Radio Science. Vol. 23(2), pp. 97-105.
Abstract: Simultaneous UHF and VHF radar observations of the 60–90 km mesosphere at Arecibo were made during the occurrence of a January 1981 type 4 solar X ray flare. The observations involved use of the UHF incoherent scatter technique at 430 MHz and the VHF turbulent scatter technique at 46.8 MHz. These observations provided a unique opportunity to test the basic premises of the turbulent gradient mixing hypothesis. UHF measurements show that enhanced electron concentration gradients were established with the flare onset. Two turbulent layers were observed with the 46.8 MHz radar before, during and after the flare. Enhanced scattering from both layers peaked within 3–6 min of the beginning of the flare. Only a slight variability in Doppler width of VHF returns from both layers was observed over the pre- to post flare period indicating that the power dissipation associated with turbulence remained essentially constant. We find that almost all the enhancement of VHF signals can be attributed to the flare induced increase in electron concentration gradients. We also conclude that the observed delay of 3–6 min between flare onset and the peak of VHF returns is related to an eddy overturning time required for mixing-in of gradients to the Bragg scale.
BibTeX:
@article{Rastogi1988,
  author = {Rastogi, P. K. and Mathews, J. D. and Ying, W.-P. and RÆttger, J.},
  title = {Simultaneous VHF and UHF radar observations of the mesosphere at Arecibo during a solar flare: A check on the gradient-mixing hypothesis},
  journal = {Radio Science},
  year = {1988},
  volume = {23},
  number = {2},
  pages = {97-105},
  url = {http://dx.doi.org/10.1029/RS023i002p00097},
  doi = {10.1029/RS023i002p00097}
}
Tong Y, Mathews JD and Ying WP (1988), "An upper E region quarterdiurnal tide at Arecibo?", Journal of Geophysical Research: Space Physics. Vol. 93(A9), pp. 10047-10051.
Abstract: Studies of the time-height trajectories of ionosphere E region layers at Arecibo have revealed not only the usual diurnal sporadic-E and semidiurnal intermediate layer structures but also that on occasion, extra layers form and descend through the E region. In particular, during January 1981, four layers per day were observed to descend through the upper E region. This four-per-day layer system was remarkably coherent over the 3 days of observation and suggests the existence of a 6-hour period or quarterdiurnal tidal wind system in the upper E region. Numerical simulations of ion trajectories in a realistic model atmosphere with diurnal, semidiurnal, and quarterdiurnal tidal wind systems of appropriate amplitude and phase structures confirm that the presence of a quarterdiurnal tide is sufficient to explain the observations.
BibTeX:
@article{Tong1988,
  author = {Tong, Yu and Mathews, J. D. and Ying, W. -P.},
  title = {An upper E region quarterdiurnal tide at Arecibo?},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1988},
  volume = {93},
  number = {A9},
  pages = {10047-10051},
  url = {http://dx.doi.org/10.1029/JA093iA09p10047},
  doi = {10.1029/JA093iA09p10047}
}
Burnside RG, Tepley CA and Wickwar VB (1987), "The O+- O collision cross-section - Can it be inferred from aeronomical measurements?", Annales Geophysicae. Vol. 5A(6), pp. 343-349.
Abstract: Direct Fabry-Perot observations of the meridional component of the thermospheric neutral wind at Arecibo, Puerto Rico, are compared with the velocities derived from simultaneous incoherent scatter radar observations. If it is assumed that there are no systematic errors in the atomic oxygen densities predicted by the MSIS-83 empirical model, the velocities determined by the two techniques agree best when the commonly accepted value of the O(+)-O collision cross-section is increased by a factor of 1.7 (+ 0.7, -0.3).
BibTeX:
@article{Burnside1987,
  author = {Burnside, R G and Tepley, C A and Wickwar, V B},
  title = {The O+- O collision cross-section - Can it be inferred from aeronomical measurements?},
  journal = {Annales Geophysicae},
  year = {1987},
  volume = {5A},
  number = {6},
  pages = {343-349},
  url = {http://adsabs.harvard.edu/abs/1987AnGeo...5..343B}
}
Burnside RG, Walker JCG and Sulzer MP (1987), "Kinematic properties of the F region ion velocity field inferred from incoherent scatter radar measurements at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 92(A4), pp. 3345-3355.
Abstract: A new multiple-frequency incoherent scatter observing technique has improved the precision of F region ion velocity measurements at Arecibo. This technique makes it possible to analyze velocity data without making the assumption that the horizontal gradients in each component of the velocity vector are zero. By assuming that spatial gradients in ion velocity are constant and that the magnetic field line through the F region is equipotential it is possible to determine completely the variation of the ion velocity vector in the plane of the magnetic meridian. The horizontal divergence of the velocity vector is generally observed to be small. At night the most significant spatial variation in the ion velocity field is usually converging flow parallel to the magnetic field; this reverses to diverging flow in the daytime. Neglect of these horizontal gradients in the vertical ion velocity can result in systematic errors in the evaluation of the meridional ion velocity as large as 30 m s?1.
BibTeX:
@article{Burnside1987a,
  author = {Burnside, R. G. and Walker, J. C. G. and Sulzer, M. P.},
  title = {Kinematic properties of the F region ion velocity field inferred from incoherent scatter radar measurements at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1987},
  volume = {92},
  number = {A4},
  pages = {3345-3355},
  url = {http://dx.doi.org/10.1029/JA092iA04p03345},
  doi = {10.1029/JA092iA04p03345}
}
Djuth FT, Jost RJ, Ierkic HM, Sulzer MP and Noble ST (1987), "Observations of HF-enhanced ion waves in the ionosphere", Geophysical Research Letters. Vol. 14(3), pp. 194-197.
Abstract: A 138.8 MHz backscatter radar has been deployed at Arecibo Observatory in Puerto Rico to monitor modifications to the ionospheric F region produced by a high-power, HF (3-5 MHz) radio wave. This radar provides a new diagnostic tool for examining wave production in the plasma at long (~ 1 m) wavelengths. When high-power radio waves are transmitted, strongly enhanced ion-acoustic waves are detected. The temporal development of the HF-enhanced ion waves at 138.8 MHz exhibits an "overshoot" behavior similar to that of HF-induced Langmuir waves and ion waves monitored in the past with the Arecibo 430 MHz radar.
BibTeX:
@article{Djuth1987,
  author = {Djuth, F. T. and Jost, R. J. and Ierkic, H. M. and Sulzer, M. P. and Noble, S. T.},
  title = {Observations of HF-enhanced ion waves in the ionosphere},
  journal = {Geophysical Research Letters},
  year = {1987},
  volume = {14},
  number = {3},
  pages = {194-197},
  url = {http://dx.doi.org/10.1029/GL014i003p00194},
  doi = {10.1029/GL014i003p00194}
}
Djuth FT, ThidÈ B, Ierkic HM and Sulzer MP (1987), "Large F-region electron-temperature enhancements generated by high-power HF radio waves", Geophysical Research Letters. Vol. 14(9), pp. 953-956.
Abstract: During recent experiments at Arecibo, Puerto Rico, large (1000-2000 K) enhancements in electron temperature have been observed when high-power radio waves reflect near the nighttime F region peak. The electron temperature enhancements are accompanied by significant (50-300 K) increases in ion temperature, large (10-15%) reductions in electron density, and strong HF-induced spread F. When large electron temperature enhancements develop, the ionosphere appears to become dynamically unstable resulting in the production of geomagnetic field-aligned striations having elevated electron temperatures and depleted electron densities.
BibTeX:
@article{Djuth1987a,
  author = {Djuth, F. T. and ThidÈ, B. and Ierkic, H. M. and Sulzer, M. P.},
  title = {Large F-region electron-temperature enhancements generated by high-power HF radio waves},
  journal = {Geophysical Research Letters},
  year = {1987},
  volume = {14},
  number = {9},
  pages = {953-956},
  url = {http://dx.doi.org/10.1029/GL014i009p00953},
  doi = {10.1029/GL014i009p00953}
}
Fejer JA and Sulzer MP (1987), "Observation of suprathermal electron fluxes during ionospheric modification experiments", Journal of Geophysical Research: Space Physics. Vol. 92(A4), pp. 3441-3444.
Abstract: The temporal behavior of backscatter by ionospheric Langmuir waves was observed with the 430-MHz radar at Arecibo while a powerful HF wave was cycled 2 s on, 3 s off. The time resolution was 0.1 s. Late at night, in the absence of photoelectrons, using an HF equivalent radiated power of 80 MW at 3.175 MHz, the initial enhancement of about 6% above system noise of the backscattered power with Doppler shifts between -3.75 and -3.85 MHz was reached about 0.25 s after switching on the HF transmitter. In the following second the enhancement gradually decreased to about 3% and remained there until switching off. During the late afternoon, in the presence of photoelectrons, using the same HF power at 5.1 MHz, an initial enhancement by 25% of the backscattered power with Doppler shifts between -5.25 and -5.35 MHz appeared within less than 0.1 s after switching on the HF transmitter. The incoherent backscatter by Langmuir waves enhanced by photoelectrons was already above system noise by a factor greatly in excess of 10 before switching on the HF transmitter; the 25% enhancement thus corresponds to an enhancement greatly in excess of 250% above system noise. The enhancement drops to less than one tenth of its original value in less than a second. The nighttime effect is attributed to multiple acceleration of electrons from the high-energy tail of the Maxwellian distribution. The daytime effect is believed to be due to a modification in the distribution function of photoelectrons.
BibTeX:
@article{Fejer1987,
  author = {Fejer, J. A. and Sulzer, M. P.},
  title = {Observation of suprathermal electron fluxes during ionospheric modification experiments},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1987},
  volume = {92},
  number = {A4},
  pages = {3441-3444},
  url = {http://dx.doi.org/10.1029/JA092iA04p03441},
  doi = {10.1029/JA092iA04p03441}
}
Forbes J, Oliver W, Burnside R and Tepley C (1987), "Thermospheric tides during thermosphere mapping study periods", Advances in Space Research. Vol. 7(10), pp. 277-283.
BibTeX:
@article{Forbes1987,
  author = {J.M. Forbes and W.L. Oliver and R.G. Burnside and C.A. Tepley},
  title = {Thermospheric tides during thermosphere mapping study periods},
  journal = {Advances in Space Research},
  year = {1987},
  volume = {7},
  number = {10},
  pages = {277-283},
  doi = {10.1016/0273-1177(87)90101-3}
}
Fukuyama K, Maekawa Y, Fukao S and Kato S (1987), "Ionospheric D-region temperatures, and electron and neutral densities observed by the incoherent scatter technique at Arecibo", Annales Geophysicae. Vol. 5, pp. 289-296.
BibTeX:
@article{Fukuyama1987,
  author = {Fukuyama, K. and Maekawa, Y. and Fukao, S. and Kato, S.},
  title = {Ionospheric D-region temperatures, and electron and neutral densities observed by the incoherent scatter technique at Arecibo},
  journal = {Annales Geophysicae},
  year = {1987},
  volume = {5},
  pages = {289-296},
  url = {http://adsabs.harvard.edu/abs/1987AnGeo...5..289F}
}
Ganguly S, Behnke RA and Emery BA (1987), "Average electric field behavior in the ionosphere above Arecibo", Journal of Geophysical Research: Space Physics. Vol. 92(A2), pp. 1199-1210.
Abstract: Plasma drift measurements taken at Arecibo during the solar minimum period of 1974-1977 are examined to determine their average behavior in the E, F1, and F regions. The drifts are generally diurnal in the E region and semidiurnal in the F1 region. These lower thermospheric drifts are set up by polarization fields generated by propagating and in situ atmospheric tides. In the F region the diurnal component is more pronounced, especially in the zonal direction. The magnitude of the drifts is of the order of 25–30 m/s (or 1 mV/m). Enhanced geomagnetic activity appears to increase the westward component of the drift in agreement with the theory of the ionospheric disturbance dynamo (Blanc and Richmond, 1980). Nighttime drifts appear to be at least partly explained in terms of polarization fields.
BibTeX:
@article{Ganguly1987,
  author = {Ganguly, Suman and Behnke, Richard A. and Emery, Barbara A.},
  title = {Average electric field behavior in the ionosphere above Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1987},
  volume = {92},
  number = {A2},
  pages = {1199-1210},
  url = {http://dx.doi.org/10.1029/JA092iA02p01199},
  doi = {10.1029/JA092iA02p01199}
}
Ganguly S and Coco D (1987), "Incoherent scattering from the collision dominated D-region. Comparison of theories with experimental data", Journal of Atmospheric and Terrestrial Physics. Vol. 49, pp. 549-563. Elsevier Science.
BibTeX:
@article{Ganguly1987a,
  author = {S. Ganguly and David Coco},
  title = {Incoherent scattering from the collision dominated D-region. Comparison of theories with experimental data},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  publisher = {Elsevier Science},
  year = {1987},
  volume = {49},
  pages = {549-563},
  doi = {10.1016/0021-9169(87)90070-5}
}
Isham B, Birkmayer W, Hagfors T and Kofman W (1987), "Observations of small-scale plasma density depletions in Arecibo HF Heating Experiments", Journal of Geophysical Research: Space Physics. Vol. 92(A5), pp. 4629-4637.
Abstract: Observations of incoherent scattering of electromagnetic waves at UHF from Langmuir waves by a new scheme involving linear frequency modulation (chirping) of a UHF transmitter and the demodulation (dechirping) of the received signals have been applied during HF heating experiments. These observations show that the high power HF wave used for ionospheric modification creates small-scale plasma depletions instantly on a time scale of 5 ms. For a plasma frequency of 5.1 MHz, plasma frequency gradient of the order of 50 kHz/km, and power density input of the HF heater wave of 8.0 â 1e5 W/m² the depletion ranged from 3 to 5%. This appears to provide direct evidence that the HF-induced modifications involve Langmuir waves trapped in density cavities.
BibTeX:
@article{Isham1987,
  author = {Isham, B. and Birkmayer, W. and Hagfors, T. and Kofman, W.},
  title = {Observations of small-scale plasma density depletions in Arecibo HF Heating Experiments},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1987},
  volume = {92},
  number = {A5},
  pages = {4629-4637},
  url = {http://dx.doi.org/10.1029/JA092iA05p04629},
  doi = {10.1029/JA092iA05p04629}
}
Kerr RB, Tepley CA, Cageao RP, Atreya SK, Donahue TM and Cherchneff IM (1987), "Observations of comet Halley at Halpha and 6300 A", Geophysical Research Letters. Vol. 14(1), pp. 53-56.
BibTeX:
@article{Kerr1987,
  author = {Kerr, R. B. and Tepley, C. A. and Cageao, R. P. and Atreya, S. K. and Donahue, T. M. and Cherchneff, I. M.},
  title = {Observations of comet Halley at Halpha and 6300 A},
  journal = {Geophysical Research Letters},
  year = {1987},
  volume = {14},
  number = {1},
  pages = {53-56},
  url = {http://dx.doi.org/10.1029/GL014i001p00053},
  doi = {10.1029/GL014i001p00053}
}
Larsen MF and Rottger J (1987), "Observations of Thunderstorm Reflectivities and Doppler Velocities Measured at VHF and UHF", Journal of Atmospheric and Oceanic Technology. Vol. 4(1), pp. 151-159.
Abstract: We compare observations of thunderstorms made with two radars operating at different wavelengths of 70 cm and 5.67 m. The first set of observations was made with the UHF radar at the Arecibo Observatory in Puerto Rico, and the second was made with the Max-Planck-Institut fÝr Aeronomie VHF radar in the Harz Mountains in West Germany. Both sets of observations show large echo strengths during periods of convective activity. We show, based on the observational data and calculations, that precipitation completely dominates the UHF signals. In fact, a sensitive UHF radar such as at the Arecibo facility is a good tool for investigating cloud droplet distributions in the upper parts of the clouds. The signal at VHF has contributions from both precipitation and the turbulent scatter, and the two contributions can easily be separated since the droplet fall velocity and the updraft velocity are different, except for the smallest drop sizes. Our results show that VHF and UHF are potentially a good combination of frequencies for cloud physics research.
BibTeX:
@article{Larsen1987,
  author = {Larsen, M. F. and Rottger, J.},
  title = {Observations of Thunderstorm Reflectivities and Doppler Velocities Measured at VHF and UHF},
  journal = {Journal of Atmospheric and Oceanic Technology},
  year = {1987},
  volume = {4},
  number = {1},
  pages = {151-159},
  url = {http://dx.doi.org/10.1175/1520-0426(1987)004<0151:OOTRAD>2.0.CO;2}
}
Maekawa Y, Fukao S, Hirota I, Sulzer MP and Kato S (1987), "Some further results on long term mesospheric and lower thermospheric wind observations by the Arecibo UHF radar", Journal of Atmospheric and Terrestrial Physics . Vol. 49(1), pp. 63-71.
Abstract: A second series of long term mesospheric and lower thermospheric wind observations was conducted at Arecibo (18.4°N, 66.8°W) between 6 and 20 March 1981 using the UHF Doppler radar, following the first observations in August 1980 (Hirota et al., 1983). Zonal and meridional wind velocities were measured during the morning (8–10 LT) and afternoon (13–15 LT) periods. The mean wind profile averaged over the entire observational period shows the predominance of the diurnal tide. The fluctuating wind vector rotates clockwise relative to height with a characteristic vertical scale of about 10 km. The phase difference inferred by a cross correlation analysis between morning and afternoon profiles indicates that the dominant period is about 20–30 h. This oscillation is discussed in relation to internal inertia-gravity waves observed by the same radar in the lower stratosphere. On the other hand, wind fluctuation with a vertical scale larger than 20 km shows a substantial day-to-day variation with a period of 5–8 days. This long period oscillation shows a good correlation with the global scale geopotential height anomalies at 1 mb (46–48 km) observed by the Tiros-N satellite at 20°N. Our evidence suggests that westward travelling planetary-scale waves with zonal wavenumber one may propagate up to the lower thermosphere.
BibTeX:
@article{Maekawa1987,
  author = {Yasuyuki Maekawa and Shoichiro Fukao and Isamu Hirota and Michael P. Sulzer and Susumu Kato},
  title = {Some further results on long term mesospheric and lower thermospheric wind observations by the Arecibo UHF radar},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1987},
  volume = {49},
  number = {1},
  pages = {63-71},
  url = {http://www.sciencedirect.com/science/article/pii/0021916987900833},
  doi = {10.1016/0021-9169(87)90083-3}
}
Maekawa Y, Fukao S and Kato S (1987), "Vertical propagation characteristics of internal gravity waves around the mesopause observed by the Arecibo UHF radar", Journal of Atmospheric and Terrestrial Physics . Vol. 49(1), pp. 73-80.
Abstract: A high resolution wind observation of the mesosphere and lower thermosphere (73–95 km) was conducted with the aid of the high power UHF Doppler radar at Arecibo (18.4°N, 66.8°W). Zonal wind velocities were continuously observed during day-time hours on 1–15 August 1980. We discuss here the observed wind fluctuations with periods of 1–4 h in the light of internal gravity waves. The phase propagation associated with these fluctuations is, on average, shown to be downward, indicating an upward energy flux. A space-time spectral analysis shows that waves with vertical wavelengths shorter than 10 km disappear around the mesopause (about 85km), while those with longer vertical wavelengths exist throughout the observational height. This result is explained in terms of wave absorption at a critical layer where the mean zonal wind has a westerly shear with height. This feature is consistent with the behavior expected for internal gravity waves around the summer mesopause in order to explain general circulation models.
BibTeX:
@article{Maekawa1987a,
  author = {Yasuyuki Maekawa and Shoichiro Fukao and Susumu Kato},
  title = {Vertical propagation characteristics of internal gravity waves around the mesopause observed by the Arecibo UHF radar},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1987},
  volume = {49},
  number = {1},
  pages = {73-80},
  url = {http://www.sciencedirect.com/science/article/pii/0021916987900845},
  doi = {10.1016/0021-9169(87)90084-5}
}
Mahajan K and Kohli R (1987), "Search for a thickness parameter for the bottomside ionospheric F-region from incoherent-scatter electron-density profiles", Advances in Space Research . Vol. 7(6), pp. 57-60.
BibTeX:
@article{Mahajan1987,
  author = {K.K. Mahajan and R. Kohli},
  title = {Search for a thickness parameter for the bottomside ionospheric F-region from incoherent-scatter electron-density profiles},
  journal = {Advances in Space Research },
  year = {1987},
  volume = {7},
  number = {6},
  pages = {57-60},
  doi = {10.1016/0273-1177(87)90272-9}
}
Noble ST, Djuth FT, Jost RJ, Gordon WE, Hedberg A, ThidÈ B, Derblom H, Bostrom R, Nielsen E, Stubbe P and Kopka H (1987), "Multiple frequency radar observations of high-latitude E region Irregularities in the HF modified ionosphere", Journal of Geophysical Research: Space Physics. Vol. 92(A12), pp. 13613-13627.
Abstract: In September 1983, experiments were conducted in Scandinavia using the high-power heating facility near TromsÜ, Norway, The purpose of the HF ionospheric modification experiments was to investigate the behavior of artificially produced E region irregularities at auroral latitudes. The majority of observations were made with backscatter radars operating at 46.9 and 143.8 MHz, but limited observations were also made at 21.4 and 140.0 MHz. These radars are sensitive to irregularities having scale lengths of between 1 and 7 m across the geomagnetic field lines. The growth and decay of the irregularities are scale length dependent with the shorter lengths growing and dissipating more rapidly than the longer lengths (e-folding growth times = 10¹–10² ms; decay times = 10²–10¨ ms). During periods of full power ordinary mode heating, irregularities having peak cross sections of 104 m² at 46.9 MHz and 105 m² at 143.8 MHz are observed. However, the cross sections normally measured are 1 to 2 orders of magnitude smaller than the peak values. The cross sections are nonlinearly dependent on the HF power and begin to saturate at levels greater than 50–75 percent of full power. Past E and F region data from Arecibo are used in conjunction with the TromsÜ measurements to ascertain the relative roles played by various mechanisms in exciting irregularities. In the E region, the results tend to favor those instability processes which operate at the upper hybrid resonance level (e.g., thermal parametric and resonance instabilities) over those that operate at the reflection level (e.g., parametric decay instability). However, it is likely that any of the mechanisms studied could at times contribute to irregularity production in the E region. At F region altitudes, the findings show support for the parametric decay, four-wave thermal parametric, and resonance instabilities. The aspect sensitivity of the irregularities is measured using the 140.0 and 143.8 MHz radars. The results indicate a reduction in echo strength of 8–14 dB/deg for geometries that do not match those for specular reflection.
BibTeX:
@article{Noble1987,
  author = {Noble, S. T. and Djuth, F. T. and Jost, R. J. and Gordon, W. E. and Hedberg, A. and ThidÈ, B. and Derblom, H. and Bostrom, R. and Nielsen, E. and Stubbe, P. and Kopka, H.},
  title = {Multiple frequency radar observations of high-latitude E region Irregularities in the HF modified ionosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1987},
  volume = {92},
  number = {A12},
  pages = {13613-13627},
  url = {http://dx.doi.org/10.1029/JA092iA12p13613},
  doi = {10.1029/JA092iA12p13613}
}
Rottger J (1987), "The relation of gravity waves and turbulence in the mesosphere", Advances in Space Research. Vol. 7(10), pp. 345-348.
BibTeX:
@article{Roettger1987,
  author = {Jurgen Rottger},
  title = {The relation of gravity waves and turbulence in the mesosphere},
  journal = {Advances in Space Research},
  year = {1987},
  volume = {7},
  number = {10},
  pages = {345-348},
  doi = {10.1016/0273-1177(87)90111-6}
}
Tepley CA and Kerr RB (1987), "Temporal, seasonal, and solar cycle variations of the topside proton concentration at Arecibo", Advances in Space Research. Vol. 7, pp. 291-294.
BibTeX:
@article{Tepley1987,
  author = {Tepley, C A and Kerr, R B},
  title = {Temporal, seasonal, and solar cycle variations of the topside proton concentration at Arecibo},
  journal = {Advances in Space Research},
  year = {1987},
  volume = {7},
  pages = {291-294},
  doi = {10.1016/0273-1177(87)90103-7}
}
Werner D and Ferraro A (1987), "Steerable ELF/VLF radiation produced by an array of ionospheric dipoles generated from HF heating", IEEE Transactions on Antennas and Propagation. Vol. 35(9), pp. 1022-1030.
Abstract: A very low frequency (VLF) or extremely low frequency (ELF) dipole source has been created within the lower ionosphere by modulating the atmospheric dynamo currents with a ground-based high power HF source from the Arecibo Observatory. The authors and their colleagues have demonstrated that ELF or VLF generated in this way and injected into the earth-ionosphere waveguide could be received a few thousand kilometers away. The injection properties due to an array of ionospheric dipoles as a function of array geometry and element currents that will allow steerable ELF/VLF radiation within the earth-ionosphere waveguide are investigated theoretically. The ionospheric array factors for a linear and a planar array of Hertzian dipole sources are developed and their properties examined. The principle of pattern multiplication is then applied to include the effect of the ionospheric array element. This provides a means for predicting the field strengths at a remote receiving site due to a steerable linear or planar array of ionospheric sources generated by high power HF periodic plasma heating.
BibTeX:
@article{Werner1987,
  author = {Werner, D.H. and Ferraro, A.},
  title = {Steerable ELF/VLF radiation produced by an array of ionospheric dipoles generated from HF heating},
  journal = {IEEE Transactions on Antennas and Propagation},
  year = {1987},
  volume = {35},
  number = {9},
  pages = {1022-1030},
  doi = {10.1109/TAP.1987.1144214}
}
Wong AY, Tanikawa T and Kuthi A (1987), "Observation of ionospheric cavitons", Physical Review Letters., Mar, 1987. Vol. 58, pp. 1375-1378. American Physical Society.
BibTeX:
@article{Wong1987,
  author = {Wong, A. Y. and Tanikawa, T. and Kuthi, A.},
  title = {Observation of ionospheric cavitons},
  journal = {Physical Review Letters},
  publisher = {American Physical Society},
  year = {1987},
  volume = {58},
  pages = {1375-1378},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.58.1375},
  doi = {10.1103/PhysRevLett.58.1375}
}
Ying W-P, Mathews JD and Rastogi PK (1987), "Interference detection and correction applied to D region incoherent scatter radar power spectral measurements", Radio Science. Vol. 22(2), pp. 307-312.
BibTeX:
@article{Ying1987,
  author = {Ying, W.-P. and Mathews, J. D. and Rastogi, P. K.},
  title = {Interference detection and correction applied to D region incoherent scatter radar power spectral measurements},
  journal = {Radio Science},
  year = {1987},
  volume = {22},
  number = {2},
  pages = {307-312},
  doi = {10.1029/RS022i002p00307}
}
MAEKAWA Y, ASO T, R&Ouml;TTGER J, CZECHOWSKY P, R&Uuml;STER R, SCHMIDT G, HIROTA I, WOODMAN RF and KATO S (1986), "A Cooperative Synchronous Observation of Winds and Tides in the Tropical Lower Stratosphere and Mesosphere Using VHF Radars at Jicamarca and Arecibo", Journal of geomagnetism and geoelectricity. Vol. 38(2), pp. 81-97.
Abstract: A cooperative synchronous observation of winds in the tropical lower stratosphere and mesosphere was carried out using VHF radars at Jicamarca (11.95°S, 76.87°W) and at Arecibo (18.35°N, 66.75°W) on 19-21 or 23 November 1981. The comparison between observations about symmetrical north and south of the equator is focussed on the mean and tidal wind characteristics. Vertical structures of the mean zonal winds at both observational stations are in fairly good agreement with the CIRA (1972) zonal circulation model at the corresponding latitudes. The nature of lower stratospheric diurnal tides is similar between Jicamarca and Arecibo. Their vertical profiles generally correspond to the theoretical predictions based on the fundamental tidal modes. The vertical scale of the tidal components including higher-order modes is shown to be longer than 10km. In the mesosphere, vertically propagating diurnal tide which is expected to be predominant at lower latitudes is partially detected in daytime at Arecibo, while it is not so well-defined at Jicamarca, suggesting a variable nature of the relevant tidal modes.
BibTeX:
@article{198681,
  author = {Yasuyuki MAEKAWA and Takehiko ASO and J&uuml;rgen R&Ouml;TTGER and Peter CZECHOWSKY and R&uuml;diger R&Uuml;STER and Gerhard SCHMIDT and Isamu HIROTA and Ronald F. WOODMAN and Susumu KATO},
  title = {A Cooperative Synchronous Observation of Winds and Tides in the Tropical Lower Stratosphere and Mesosphere Using VHF Radars at Jicamarca and Arecibo},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1986},
  volume = {38},
  number = {2},
  pages = {81-97},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/38/2/38_2_81/_article},
  doi = {10.5636/jgg.38.81}
}
Birkmayer W and Hagfors T (1986), "Observational technique and parameter estimation in plasma line spectrum observations of the ionosphere by chirped incoherent scatter radar", Journal of Atmospheric and Terrestrial Physics. Vol. 48(9-10), pp. 1009-1019.
BibTeX:
@article{Birkmayer1986,
  author = {Birkmayer, W. and Hagfors, T.},
  title = {Observational technique and parameter estimation in plasma line spectrum observations of the ionosphere by chirped incoherent scatter radar},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1986},
  volume = {48},
  number = {9-10},
  pages = {1009-1019},
  doi = {10.1016/0021-9169(86)90072-3}
}
Birkmayer W, Hagfors T and Kofman W (1986), "Small-Scale Plasma-Density Depletions in Arecibo High-Frequency Modification Experiments", Physical Review Letters. Vol. 57, pp. 1008-1011.
Abstract: Observations of Thomson scattering at uhf from Langmuir waves by a scheme involving the linear frequency modulation (chirping) of a uhf transmitter and the demodulation (dechirping) of the received signals show that a high-power hf wave used for ionospheric modification creates small-scale plasma depletions instantly. For a plasma frequency of 5.1 MHz, plasma frequency gradient of about 50 kHz/km, and power density input of 8â10-5 W/m2, the depletion ranged from 3% to 55%. This provides direct evidence that the hf-induced modifications involve Langmuir waves trapped in density cavities.
BibTeX:
@article{Birkmayer1986a,
  author = {Birkmayer, W. and Hagfors, T. and Kofman, W.},
  title = {Small-Scale Plasma-Density Depletions in Arecibo High-Frequency Modification Experiments},
  journal = {Physical Review Letters},
  year = {1986},
  volume = {57},
  pages = {1008-1011},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.57.1008},
  doi = {10.1103/PhysRevLett.57.1008}
}
Colgan SWJ and Terzian Y (1986), "H I calibration measurements at Arecibo Observatory", Radio Science. Vol. 21(4), pp. 761-768.
Abstract: From an analysis of galactic H I spectra acquired over a period of seven months, we investigate the accuracy of H I profiles obtained with the dual circular feed at Arecibo Observatory. The H I stray radiation contribution is estimated from a comparison of H I spectra toward the moon with H I spectra in the same direction when the moon is absent. The profile areas of corrected H I spectra are accurate to 3%, while individual features are accurate to 15%. At velocities where the H I emission is less than 3 K, the observed stray radiation is less than 0.5 K.
BibTeX:
@article{Colgan1986,
  author = {Colgan, Sean W. J. and Terzian, Yervant},
  title = {H I calibration measurements at Arecibo Observatory},
  journal = {Radio Science},
  year = {1986},
  volume = {21},
  number = {4},
  pages = {761-768},
  url = {http://dx.doi.org/10.1029/RS021i004p00761},
  doi = {10.1029/RS021i004p00761}
}
Crary DJ and Forbes JM (1986), "The dynamic ionosphere over Arecibo: A theoretical investigation", Journal of Geophysical Research: Space Physics. Vol. 91(A1), pp. 249-258.
Abstract: Numerical simulations of the F region ionosphere over Arecibo, Puerto Rico, are presented. We deduce from these simulations that the dynamic behavior of the Arecibo ionosphere, particularly the so-called “midnight collapse” phenomenon, is strongly influenced by the upward propagating semidiurnal tidal component of the neutral meridional wind excited below thermospheric levels. Presence of a terdiurnal component in the wind field improves the agreement with experiment and could result from nonlinear interactive coupling between the neutral wind and ion drag. The steep underside density gradients occurring in conjunction with the collapse are due to vertical shear in the meridional wind field associated with the propagating semidiurnal tide. These gradients are capable of triggering the gradient drift instability, thus accounting for plasma irregularity formation and observations of VHF scintillations associated with the collapse phenomenon.
BibTeX:
@article{Crary1986,
  author = {Crary, David J. and Forbes, Jeffrey M.},
  title = {The dynamic ionosphere over Arecibo: A theoretical investigation},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1986},
  volume = {91},
  number = {A1},
  pages = {249-258},
  url = {http://dx.doi.org/10.1029/JA091iA01p00249},
  doi = {10.1029/JA091iA01p00249}
}
Djuth FT, Gonzales CA and Ierkic HM (1986), "Temporal evolution of the HF-enhanced plasma line in the Arecibo F region", Journal of Geophysical Research: Space Physics. Vol. 91(A11), pp. 12089-12107.
Abstract: The temporal development of the so-called HF-enhanced plasma line (HFPL) has been studied in detail using the high-power high-frequency (HF) facility located near Arecibo, Puerto Rico. Observations were made with the Arecibo 430-MHz radar. In the current work, attention is focused on the evolution of the HFPL spectrum subsequent to the onset of the HF wave in the F region plasma. The development of the HFPL spectrum is examined for several different HF pulse lengths and HF duty cycles. In this regard, low duty cycles with long HF-off periods tend to consistently produce a different spectral evolution than high duty cycles with short HF-off periods. Broad, diffuse HFPL spectra are observed with low HF duty cycles, whereas sharply defined nonlinear Landau damping cascades develop at high duty cycles. Under a variety of observing conditions, the Arecibo HFPLs are found to develop dominant decay line peaks within a few milliseconds of HF turn-on in the plasma. In addition, at early times during periods of slow HFPL growth, and also for very low HF power levels, weak flat-top and/or double-humped spectral features are observed that can be attributed to radio wave scattering off ion acoustic waves. During periods of strong HFPL excitation, weak spectral signatures are occasionally observed in the band 430 MHz ± (fHF + delta), where fHF is the HF frequency and delta = 10–100 kHz. The origin of this structure is currently not known. Finally, the temporal development of the 430-MHz spectra is closely examined during the so-called main plasma line overshoot. A diffuse spectral cascade is evident within a few milliseconds of the onset of the HF wave in the plasma, and dominant decay line peaks quickly develop thereafter. Processes involving direct conversion of the HF wave into Langmuir waves and/or soliton formation do not appear to be the dominant processes responsible for the 430-MHz HFPLs observed in the Arecibo F region. However, the formation of solitons may influence the development of the HFPLs. The measured HFPL spectra are in qualitative agreement with the predictions of nonlinear Landau damping theory, but the experimental observations do not match the theoretical predictions in every detail. It is likely that HF-induced small-scale cavities and/or HF-induced geomagnetic field-aligned irregularities play a central role in determining the amplitude, spectral signature, and temporal development of strongly excited HFPLs at Arecibo.
BibTeX:
@article{Djuth1986,
  author = {Djuth, F. T. and Gonzales, C. A. and Ierkic, H. M.},
  title = {Temporal evolution of the HF-enhanced plasma line in the Arecibo F region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1986},
  volume = {91},
  number = {A11},
  pages = {12089-12107},
  url = {http://dx.doi.org/10.1029/JA091iA11p12089},
  doi = {10.1029/JA091iA11p12089}
}
Ganguly S (1986), "Experimental observations of ultra-low-frequency waves generated in the ionosphere", Nature. Vol. 320(6062), pp. 511-513.
BibTeX:
@article{Ganguly1986,
  author = {Suman Ganguly},
  title = {Experimental observations of ultra-low-frequency waves generated in the ionosphere},
  journal = {Nature},
  year = {1986},
  volume = {320},
  number = {6062},
  pages = {511-513},
  doi = {10.1038/320511b0}
}
Ganguly S and Gordon WE (1986), "Nonlinear mixing in the ionosphere", Geophysical Research Letters. Vol. 13(6), pp. 503-505.
BibTeX:
@article{Ganguly1986a,
  author = {Ganguly, Suman and Gordon, W. E.},
  title = {Nonlinear mixing in the ionosphere},
  journal = {Geophysical Research Letters},
  year = {1986},
  volume = {13},
  number = {6},
  pages = {503-505},
  doi = {10.1029/GL013i006p00503}
}
German MJ and Mathews JD (1986), "Interference detection and correction applied to incoherent scatter radar power profile measurements", Radio Science. Vol. 21(4), pp. 745-751.
Abstract: Incoherent scatter radars are used principally to measure “power profiles” (total power versus range) from which electron concentration is inferred. When applied to the ionosphere D region this measurement is, due to very small signal-to-noise ratios and the range involved, especially susceptable to aircraft and meteor returns and to interference from other radars. We report a power spectrum based interference detection scheme which allows correction of the power profile. The power spectrum used is formed from the same data sequence used to form the power profile. This scheme has been successfully applied to Arecibo D region data.
BibTeX:
@article{German1986,
  author = {German, M. J. and Mathews, J. D.},
  title = {Interference detection and correction applied to incoherent scatter radar power profile measurements},
  journal = {Radio Science},
  year = {1986},
  volume = {21},
  number = {4},
  pages = {745-751},
  url = {http://dx.doi.org/10.1029/RS021i004p00745},
  doi = {10.1029/RS021i004p00745}
}
Hagen J (1986), "Communications techniques in radio physics and astronomy", IEEE Communications Magazine. Vol. 24(10), pp. 16-20.
Abstract: Not Available
BibTeX:
@article{Hagen1986,
  author = {Hagen, J.},
  title = {Communications techniques in radio physics and astronomy},
  journal = {IEEE Communications Magazine},
  year = {1986},
  volume = {24},
  number = {10},
  pages = {16-20},
  url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1092945},
  doi = {10.1109/MCOM.1986.1092945}
}
Hines CO (1986), "Comments on “Observations of Low-Frequency Inertia–Gravity Waves in the Lower Stratosphere over Arecibo”", Journal of the Atmospheric Sciences. Vol. 52, pp. 607-610.
BibTeX:
@article{Hines1986,
  author = {Colin O. Hines},
  title = {Comments on “Observations of Low-Frequency Inertia–Gravity Waves in the Lower Stratosphere over Arecibo”},
  journal = {Journal of the Atmospheric Sciences},
  year = {1986},
  volume = {52},
  pages = {607-610},
  url = {http://dx.doi.org/10.1175/1520-0469(1995)052<0607:COOLFI>2.0.CO;2}
}
Kerr RB, Atreya SK, Meriwether JW, Tepley CA and Burnside RG (1986), "Simultaneous H-alpha line profile and radar measurements at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 91(A4), pp. 4491-4512.
Abstract: High resolution measurements of the geocoronal Balmer alpha (H alpha) emission were made with a Fabry-Perot interferometer at Arecibo, Puerto Rico, in six observing campaigns between March 1980 and November 1984. Four of these included simultaneous radar measurements of the topside F region. The nighttime variation of the zenith H? intensity is highly symmetric about solar midnight. However, effective hydrogen temperatures near the morning exobase are generally hotter than near the evening exobase, implying a depletion of exobase hydrogen density in the early morning hours. The exospheric temperature is derived from the Doppler line profiles and is compared to the topside F region O+ temperature. The cooling of H relative to O+ due to the escape of hot, energetic H is not obvious in our data, and it appears that a downward flux of hot protons often causes heating of the bound neutral H population by charge exchange during low to moderate solar activity conditions. This downward flux is usually strongest between 0200 and 0600 LT, and occurs throughout the night in the late fall and early winter. We have detected a deficiency of inbound high-energy hydrogen relative to the high-energy outbound population in radial velocity H? profiles. We have also detected large distortions of the H? profile wings during low to moderate solar activity periods and during periods of large downward ion speeds. We attribute these wing distortions to efficient charge exchange of H with H+. A narrowing of zenith profile widths near midnight demonstrates the gravitational cooling of H due to the inverse relationship between geocentric distance and the kinetic energy required for escape. We have also searched for evidence that satellite hydrogen populations with small orbital eccentricities may be contributing to narrow line widths.
BibTeX:
@article{Kerr1986,
  author = {Kerr, R. B. and Atreya, S. K. and Meriwether, J. W. and Tepley, C. A. and Burnside, R. G.},
  title = {Simultaneous H-alpha line profile and radar measurements at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1986},
  volume = {91},
  number = {A4},
  pages = {4491-4512},
  url = {http://dx.doi.org/10.1029/JA091iA04p04491},
  doi = {10.1029/JA091iA04p04491}
}
Killeen TL, Roble RG, Smith RW, Spencer NW, Meriwether JW, Rees D, Hernandez G, Hays PB, Cogger LL, Sipler DP, Biondi MA and Tepley CA (1986), "Mean neutral circulation in the winter polar F region", Journal of Geophysical Research: Space Physics. Vol. 91(A2), pp. 1633-1649.
Abstract: Direct measurements of the F region neutral wind field in the northern (winter) hemisphere during late November and December 1981 were obtained by using the Dynamics Explorer (DE 2) satellite and the network of ground-based Fabry-Perot interferometers sited in the North American and Scandinavian sectors. All available data for the study period have been collated and averaged according to universal time (UT) to provide a global-scale experimental determination of the mean or average circulation in the northern hemisphere F region. The data are organized into UT “bins” and are presented as a sequence of 12 “climate maps” depicting the neutral wind system at 2-hour UT intervals during a “mean” day in December 1981. The data set provides the most comprehensive experimental measure of the global-scale high-latitude thermospheric circulation yet reported. The averaged measurements from the different instruments exhibit a satisfactory degree of internal consistency when viewed in terms of the global-scale neutral flow. A detailed comparison with the predictions of the NCAR thermospheric general circulation model is discussed. The model predictions are in good general agreement with the UT-dependent mean circulation, reproducing the basic control of the high-latitude neutral wind system by ion drag forces modulated in UT as a result of the offset between the geomagnetic and geographic poles. Differences in flow directions and velocities between model predictions and experimental results are ascribed to natural variability in the thermosphere as well as to the use in the model of a less than fully realistic, symmetric ion convection geometry and density distribution. The two basic conclusions of this study are that (1) instrumentation deployed around the globe and on satellites can provide powerful, composite data sets that can be used to monitor global-scale mean thermospheric “climatology” and that (2) the mean thermospheric (F region) neutral circulation for the given geophysical situation (solar maximum, near solstice) can be modeled reasonably well using a three-dimensional, time-dependent model with appropriate parameterizations for the energy and momentum inputs.
BibTeX:
@article{Killeen1986,
  author = {Killeen, T. L. and Roble, R. G. and Smith, R. W. and Spencer, N. W. and Meriwether, J. W. and Rees, D. and Hernandez, G. and Hays, P. B. and Cogger, L. L. and Sipler, D. P. and Biondi, M. A. and Tepley, C. A.},
  title = {Mean neutral circulation in the winter polar F region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1986},
  volume = {91},
  number = {A2},
  pages = {1633-1649},
  url = {http://dx.doi.org/10.1029/JA091iA02p01633},
  doi = {10.1029/JA091iA02p01633}
}
Larsen MF, Woodman RF, Sato T and Davis M (1986), "Power Spectra of Oblique Velocities in the Troposphere and Lower Stratosphere Observed at Arecibo, Puerto Rico", Journal of the Atmospheric Sciences. Vol. 43(20), pp. 2230-2240.
Abstract: Wind profiles measured with the Arecibo Observatory 430 MHz radar during 1979 and 1980 have been used to calculate frequency and radial wavenumber power spectra. Periods between 2 min and 6 h and vertical wavelength between 300 m and 13.5 km are covered by the spectra The data are line-of-sight velocity components obtained with a beam pointing between 5.4° and 15° off-vertical. The presented evidence supports the conclusion that the dominant contribution to the spectra at periods less than 1 h is from the vertical velocity component. The frequency spectra have spectral slopes near -1 for periods of less than 1 h, and the radial wavenumber spectra have slopes between -1 and -3/2. The results are discussed in the context of two-dimensional turbulence and a universal gravity-wave spectrum. We also present the spectra from an event associated with convection in the early evening hours. A strong peak in the spectral energy near the Brunt-VÄisÄlÄ frequency was present during the convective activity. The energy content at longer. periods was found to be enhanced in the ensuing period when the convective energy input at shorter time scales new the Brunt-VÄisÄlÄ period had diminished.
BibTeX:
@article{Larsen1986,
  author = {Larsen, M. F. and Woodman, R. F. and Sato, T. and Davis, M. ~.},
  title = {Power Spectra of Oblique Velocities in the Troposphere and Lower Stratosphere Observed at Arecibo, Puerto Rico},
  journal = {Journal of the Atmospheric Sciences},
  year = {1986},
  volume = {43},
  number = {20},
  pages = {2230-2240},
  url = {http://dx.doi.org/10.1175/1520-0469(1986)043<2230:PSOOVI>2.0.CO;2}
}
McDonald J and Williams P (1986), "Electron temperature and electron density in the F-region of the ionosphere. I. Observed relationship ", Journal of Atmospheric and Terrestrial Physics . Vol. 48(6), pp. 545-557.
Abstract: Ionospheric data from three incoherent scatter stations over the height range 225-450 km were studied for all daylight hours over a wide range of solar conditions. The relationship between electron temperature Te, electron density Nand solar flux at 10.7 cm wavelength S10.7 was expressed as Te = A-B·(N-5 â 10e11) + C·(S10.7-750), where N is in units of m-3 and S10.7 in kJy.
This provided a very satisfactory expression for all data taken at Malvern and St. Santin between 0800 and 1600 LT. For data taken at Arecibo, however, the linearity broke down at low electron densities. The data from all three stations were therefore divided into two sets according to electron density and reexamined.
For N < 5 â 10e11m-3B increased steadily with height and decreased steadily with latitude.
For N > 5 â 10e11m-3B did not appear to vary with height, with season or with latitude. C was approximately constant for all sets of data.
The different mechanisms involved in the heat balance of the electron population are discussed and a qualitative explanation for the relationship is proposed.
BibTeX:
@article{McDonald1986,
  author = {J.N. McDonald and P.J.S. Williams},
  title = {Electron temperature and electron density in the F-region of the ionosphere. I. Observed relationship },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1986},
  volume = {48},
  number = {6},
  pages = {545-557},
  url = {http://www.sciencedirect.com/science/article/pii/0021916986900887},
  doi = {10.1016/0021-9169(86)90088-7}
}
Sulzer MP (1986), "A radar technique for high range resolution incoherent scatter autocorrelation function measurements utilizing the full average power of klystron radars", Radio Science. Vol. 21(6), pp. 1033-1040.
Abstract: Incoherent scatter radar measurements with high range resolution have been made at Arecibo Observatory using a new technique, called the coded long pulse technique. This technique is similar to the multiple pulse technique in its uses, and in the way in which random clutter from unwanted ranges sets a lower limit on the noise level. It differs in that the full average power can be obtained from a radar that uses klystrons in the output stage. A description of the new technique is given, and the two techniques are compared. Some data showing the range variation of the HF induced enhanced plasma line are presented, and the superiority of the new technique for most E region measurements is demonstrated. Computational algorithms are discussed, and it is shown that in many cases the amount of computation required is not significantly more than is required by the multiple pulse technique.
BibTeX:
@article{Sulzer1986,
  author = {Sulzer, Michael P.},
  title = {A radar technique for high range resolution incoherent scatter autocorrelation function measurements utilizing the full average power of klystron radars},
  journal = {Radio Science},
  year = {1986},
  volume = {21},
  number = {6},
  pages = {1033-1040},
  url = {http://dx.doi.org/10.1029/RS021i006p01033},
  doi = {10.1029/RS021i006p01033}
}
Sulzer MP (1986), "A phase modulation technique for a sevenfold statistical improvement in incoherent scatter data-taking", Radio Science. Vol. 21(4), pp. 737-744.
Abstract: A new technique for improving the quality of data in incoherent scatter measurements is described. The technique is useful under high signal to noise ratio conditions; the number of independent samples in the estimates is increased a factor of 7 by the simultaneous transmission of multiple frequencies. This either increases the time resolution by a factor of 7, or decreases the statistical errors by a factor of the square root of 7. Three important factors concerning the implementation of the technique are discussed: (1) the generation of the multiple frequencies, (2) the required frequency spacing to assure independence of the estimates, and (3) a practical technique for combining the independent estimates. A phase coded pulse is used to generate the seven frequencies with nearly equal power. Specially designed baseband filters are used to avoid distortion in the temperature and velocity measurements. Data demonstrating the improvement are presented, and the application of the technique to other radar uses, such as tracking radars, is discussed.
BibTeX:
@article{Sulzer1986a,
  author = {Sulzer, Michael P.},
  title = {A phase modulation technique for a sevenfold statistical improvement in incoherent scatter data-taking},
  journal = {Radio Science},
  year = {1986},
  volume = {21},
  number = {4},
  pages = {737-744},
  url = {http://dx.doi.org/10.1029/RS021i004p00737},
  doi = {10.1029/RS021i004p00737}
}
Behnke R, Kelley M, Gonzales C and Larsen M (1985), "Dynamics of the Arecibo ionospheres: A case study approach", Journal of Geophysical Research. Vol. 90(A5), pp. 4448-4452.
Abstract: A number of different processes have been suggested to explain the F layer plasma drifts measured over the Arecibo Observatory. A series of experiments are described here which take advantage of neutral wind measurements now available at Arecibo as well as an unusual event during which large high-latitude electric fields penetrated to the low-latitude ionosphere. With this added information we are able to differentiate between the competing processes controlling the F layer. We show that depending on various conditions, both the F layer dynamo mechanism and the external electric field-diffusion velocity mechanism can control the dynamics of the F layer. We also present a case in which neither of these mechanisms is sufficient to explain the observed behavior of the nighttime F layer plasma. In addition, we have carried out calculations that demonstrate that during magnetically active times, the penetration electric fields can set the low-latitude thermosphere in motion via ion drag. Finally we show that at times, conjugate point electric fields appear to be present and that the conductivity at the conjugate point can dominate the local value with observable consequences.
BibTeX:
@article{Behnke1985,
  author = {Behnke, R and Kelley, M and Gonzales, C and Larsen, M},
  title = {Dynamics of the Arecibo ionospheres: A case study approach},
  journal = {Journal of Geophysical Research},
  year = {1985},
  volume = {90},
  number = {A5},
  pages = {4448-4452},
  url = {http://dx.doi.org/10.1029/JA090iA05p04448},
  doi = {10.1029/JA090iA05p04448}
}
Bilitza D (1985), "Comparison of measured and predicted F2 peak altitude", Advances in Space Research. Vol. 5(10), pp. 29-32.
BibTeX:
@article{Bilitza1985,
  author = {D. Bilitza},
  title = {Comparison of measured and predicted F2 peak altitude},
  journal = {Advances in Space Research},
  year = {1985},
  volume = {5},
  number = {10},
  pages = {29-32},
  doi = {10.1016/0273-1177(85)90176-0}
}
Bilitza D (1985), "Electron density in the equatorial topside", Advances in Space Research. Vol. 5(10), pp. 15-19.
BibTeX:
@article{Bilitza1985a,
  author = {D. Bilitza},
  title = {Electron density in the equatorial topside},
  journal = {Advances in Space Research},
  year = {1985},
  volume = {5},
  number = {10},
  pages = {15-19},
  doi = {10.1016/0273-1177(85)90174-7}
}
Burnside R, Walker J, Behnke R and Tepley C (1985), "Plasma dynamics in the night-time F-region at Arecibo ", Journal of Atmospheric and Terrestrial Physics . Vol. 47, pp. 925-939.
Abstract: Incoherent scatter radar observations of the night-time F-layer at Arecibo, Puerto Rico, are used to determine horizontal gradients in peak electron density and the F-layer height. At certain times of night, in both the summer and winter, the horizontal gradients in these parameters may be significant. The continuity equation for O+ is used to examine the sources and sinks of plasma at the peak of the night-time F-layer. In summer, before midnight, the F-layer is sufficiently elevated that chemical recombination at the peak is very slow. At these times we find that the local peak electron density may be significantly influenced by horizontal (predominantly eastward) advection or convergence of plasma. In winter, horizontal advection is usually less important than plasma convergence and chemical loss.
BibTeX:
@article{Burnside1985,
  author = {R.G Burnside and J.C.G Walker and R.A Behnke and C.A Tepley},
  title = {Plasma dynamics in the night-time F-region at Arecibo },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1985},
  volume = {47},
  pages = {925-939},
  url = {http://www.sciencedirect.com/science/article/pii/0021916985900698},
  doi = {10.1016/0021-9169(85)90069-8}
}
Cogger L, Murphree J, Tepley C and Jr. JM (1985), "Measurements of the E region neutral wind field", Planetary and Space Science . Vol. 33(4), pp. 373-379.
Abstract: The neutral E-region wind field was measured at Calgary, Canada (51°N, 114°W) during 75 nights in 1982. Observations of the Doppler shift of the 5577-å emission line of atomic oxygen using a Fabry-Perot interferometer were converted to horizontal wind vectors. From the analysis of the data, four categories of wind characteristics were identified. In order of increasing magnetic activity these categories are (a) wind field mostly variable in space and time, (b) predominantly equatorward flow throughout the night, (c) predominantly poleward flow throughout the night and (d) north-westward flow before midnight and southward after midnight. The wind magnitude was also variable and on some disturbed days exceeded 200 m s-1.
BibTeX:
@article{Cogger1985,
  author = {L.L. Cogger and J.S. Murphree and C.A. Tepley and J.W. Meriwether Jr.},
  title = {Measurements of the E region neutral wind field},
  journal = {Planetary and Space Science },
  year = {1985},
  volume = {33},
  number = {4},
  pages = {373-379},
  url = {http://www.sciencedirect.com/science/article/pii/0032063385900807},
  doi = {10.1016/0032-0633(85)90080-7}
}
Coster AJ, Djuth FT, Jost RJ and Gordon WE (1985), "The temporal evolution of 3-m striations in the modified ionosphere", Journal of Geophysical Research: Space Physics. Vol. 90(A3), pp. 2807-2818.
Abstract: Experiments were performed at Arecibo, Puerto Rico, to investigate the evolution times of 3-m field-aligned Striations produced in the ionosphere by powerful high-frequency (HF) radio waves. The results of this investigation are now summarized. First, the striations' rise times are dependent on the HF electric field. The E region data suggest that this dependence is nonlinear. Second, the threshold value of the HF electric field required to produce detectable Striations was experimentally determined. At threshold the component of the HF electric field perpendicular to the geomagnetic field is calculated to be 0.09 V/m in the F region and 0.37 V/m in the E region. Third, both the E and the F region data verify theoretical predictions that the Striations' decay times are directly proportional to the electron diffusion across B. Finally, a one-to-one correspondence between the growth of the 3-m Striations and the decline of the HF-enhanced plasma line during overshoot is sometimes observed.
BibTeX:
@article{Coster1985,
  author = {Coster, A. J. and Djuth, F. T. and Jost, R. J. and Gordon, W. E.},
  title = {The temporal evolution of 3-m striations in the modified ionosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1985},
  volume = {90},
  number = {A3},
  pages = {2807-2818},
  url = {http://dx.doi.org/10.1029/JA090iA03p02807},
  doi = {10.1029/JA090iA03p02807}
}
Duncan L (1985), "The HF-induced plasma line, electron acceleration, and resulting airglow", Journal of Atmospheric and Terrestrial Physics . Vol. 47(12), pp. 1267-1281.
BibTeX:
@article{Duncan1985,
  author = {L.M. Duncan},
  title = {The HF-induced plasma line, electron acceleration, and resulting airglow},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1985},
  volume = {47},
  number = {12},
  pages = {1267-1281},
  doi = {10.1016/0021-9169(85)90093-5}
}
Duncan LM and Sheerin JP (1985), "High-resolution studies of the HF ionospheric modification interaction region", Journal of Geophysical Research: Space Physics. Vol. 90(A9), pp. 8371-8376.
Abstract: Incoherent backscatter radar studies were conducted of the HF ionospheric modification interaction region using the facilities of the Arecibo Observatory. Very high relative spatial and temporal resolutions were achieved. These measurements resolve the miniovershoot (2–10 ms after HF on) and main overshoot (20–40 ms after HF on) plasma wave excitation features. The main overshoot phenomenon is observed to develop very reproducibly with enhancements of a factor of 10 greater than the steady state HF-enhanced plasma line intensity. However, this main overshoot effect is strongly suppressed for HF off times of less than 100 ms. In general, the miniovershoot excitation is found to occur 800–1000 m below the main overshoot excitation height. In addition, in one case, a small plasma line enhancement is detected at very early times (<1 ms) distinct from the miniovershoot and originating at a greater height. The main overshoot and the steady state enhanced plasma line both develop at essentially the same altitude. However, the interaction layer is observed to broaden by several hundred meters during the main overshoot relaxation. Possible explanations for these effects are proposed using a combination of the theories of soliton formation and collapse, wave ducting, profile modification, parametric instabilities, and other interactive processes.
BibTeX:
@article{Duncan1985a,
  author = {Duncan, L. M. and Sheerin, J. P.},
  title = {High-resolution studies of the HF ionospheric modification interaction region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1985},
  volume = {90},
  number = {A9},
  pages = {8371-8376},
  url = {http://dx.doi.org/10.1029/JA090iA09p08371},
  doi = {10.1029/JA090iA09p08371}
}
Fejer J, Gonzales C, Ierkic H, Sulzer M, Tepley C, Duncan L, Djuth F, Ganguly S and Gordon W (1985), "Ionospheric modification experiments with the Arecibo Heating Facility", Journal of Atmospheric and Terrestrial Physics . Vol. 47(12), pp. 1165-1179.
Abstract: The results obtained with ionospheric modification experiments over the three years preceding the XXI General Assembly of URSI in 1984 at Florence are reviewed. The topics discussed include weak electromagnetic sidebands observed using a single pump frequency, the HF-induced plasma line at 3.175 MHz and its similarity to the plasma lines observed using higher HF frequencies near TromsÜ, the HF-enhanced plasma line observed with the 50 MHz radar, the HF-induced plasma line with a doublehumped spectrum below threshold. HF-induced plasma line spectra with height discrimination using a new technique, the HF-induced plasma line and ion line spectra obtained with two pumps differing in frequency by a few kHz, narrow features such as the OTSI in the HF-enhanced plasma line and ion line spectra observed by a new technique, the use of such narrow features for measuring the line-of-sight electron drift velocity, the discovery of a radical qualitative change in the spectrum of the HF-induced plasma line as the HF power (CW) is increased or as the duty cycle is changed while pulsing, observations of the temporal development of the enhancement of the thermal plasma line at the peak of the F2-layer by electrons accelerated during ionospheric heating studies of artificial density stratification resulting from the standing wave nature of the heating wave and strong electromagnetic sidebands generated by two Powerful HF radio waves differing from each other by some tens of Hz. Theoretical work on soliton formation and on VLF generation by HF heating is briefly mentioned, as well as experimental studies of self-focusing by observing the scintillation of extraterrestrial radio sources, direct conversion and studies of short scale field-aligned irregularities by VHF radar backscatter during ionospheric modification.
BibTeX:
@article{Fejer1985,
  author = {J.A Fejer and C.A Gonzales and H.M Ierkic and M.P Sulzer and C.A Tepley and L.M Duncan and F.T Djuth and S Ganguly and W.E Gordon},
  title = {Ionospheric modification experiments with the Arecibo Heating Facility},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1985},
  volume = {47},
  number = {12},
  pages = {1165-1179},
  url = {http://www.sciencedirect.com/science/article/pii/0021916985900868},
  doi = {10.1016/0021-9169(85)90086-8}
}
Fukao S, Maekawa Y, Sato T and Kato S (1985), "Fine structure in mesospheric wind fluctuations observed by the Arecibo UHF Doppler radar", Journal of Geophysical Research: Space Physics. Vol. 90(A8), pp. 7547-7556.
Abstract: Mesospheric short-period wind fluctuations are investigated, using two sets of daytime wind data obtained on 15 consecutive days in August 1980 and March 1981 by the UHF Doppler radar at Arecibo, Puerto Rico (18.4°N, 66.8°W). The wind fluctuations are found to have a conspicuous recurring structure with periods of 10–20 min on a vertical scale less than a few kilometers. This structure, appearing as a “grill pattern” in the time-height sections of wind velocity, seems to indicate that both upward and downward propagating waves with similar wave parameters exist simultaneously in this height range. The wave energy is shown to be almost equally distributed between the upward and downward propagating waves. The frequency power spectrum has a falling gradient gentler than that of the f?5/3 and even of the f?1 power law (f is frequency). Occurrence of these waves seems to be related to strong wind shears associated with long-period internal inertia-gravity waves present in the mesospheric region.
BibTeX:
@article{Fukao1985,
  author = {Fukao, Shoichiro and Maekawa, Yasuyuki and Sato, Toru and Kato, Susumu},
  title = {Fine structure in mesospheric wind fluctuations observed by the Arecibo UHF Doppler radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1985},
  volume = {90},
  number = {A8},
  pages = {7547-7556},
  url = {http://dx.doi.org/10.1029/JA090iA08p07547},
  doi = {10.1029/JA090iA08p07547}
}
Ganguly S (1985), "The sunrinse and sunset transitions in the mesosphere", Journal of Atmospheric and Terrestrial Physics. Vol. 47(7), pp. 643-652.
BibTeX:
@article{Ganguly1985,
  author = {Suman Ganguly},
  title = {The sunrinse and sunset transitions in the mesosphere},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1985},
  volume = {47},
  number = {7},
  pages = {643-652},
  doi = {10.1016/0021-9169(85)90100-X}
}
Kerr R, Cageao R, Atreya S, Donahue T and Tepley C (1985), "High spectral resolution Fabry-Perot interferometer measurements of comet Halley at H-alpha and 6300 A", Advances in Space Research. Vol. 5(12), pp. 283-287.
BibTeX:
@article{Kerr1985,
  author = {R.B. Kerr and R.P. Cageao and S.K. Atreya and T.M. Donahue and C.A. Tepley},
  title = {High spectral resolution Fabry-Perot interferometer measurements of comet Halley at H-alpha and 6300 A},
  journal = {Advances in Space Research},
  year = {1985},
  volume = {5},
  number = {12},
  pages = {283-287},
  doi = {10.1016/0273-1177(85)90098-5}
}
Robinson T (1985), "Self-action effects associated with the generation of plasma irregularities during ionospheric modification experiments", Journal of Atmospheric and Terrestrial Physics . Vol. 47(12), pp. 1245-1255.
Abstract: Five poster papers presented by various authors at the URSI Symposium on Active Experiments in Space Plasmas (Florence, August 1984) are previewed. New results from the heating facilities at both Arecibo and Ramfjordmoen are reported. The observations include:
1.(a) heater generated intermediate scale plasma irregularities diagnosed by UHF radio star scintillations, UHF radar incoherent scatter and HF signal fading techniques;
2.(b) UHF plasma line enhancements;
3.(c) anomalous absorption of both heater and HF diagnostic waves.
These experimental results are discussed in terms of various self-action processes, such as self-focussing and pump depletion. The results of some recent theoretical investigations into anomalous absorption and reflection are also presented.
BibTeX:
@article{Robinson1985,
  author = {T.R. Robinson},
  title = {Self-action effects associated with the generation of plasma irregularities during ionospheric modification experiments},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1985},
  volume = {47},
  number = {12},
  pages = {1245-1255},
  url = {http://www.sciencedirect.com/science/article/pii/0021916985900911},
  doi = {10.1016/0021-9169(85)90091-1}
}
Rottger J and Ierkic HM (1985), "Postset beam steering and interferometer applications of VHF radars to study winds, waves, and turbulence in the lower and middle atmosphere", Radio Science. Vol. 20(6), pp. 1461-1480.
BibTeX:
@article{Rottger1985,
  author = {Rottger, J. and Ierkic, H. M.},
  title = {Postset beam steering and interferometer applications of VHF radars to study winds, waves, and turbulence in the lower and middle atmosphere},
  journal = {Radio Science},
  year = {1985},
  volume = {20},
  number = {6},
  pages = {1461-1480},
  doi = {10.1029/RS020i006p01461}
}
Sulzer MP and Woodman RF (1985), "Pulse compression hardware decoding techniques for MST radars", Radio Science. Vol. 20(6), pp. 1146-1154.
Abstract: The techniques for decoding in hardware received signals transmitted by phase-coded mesosphere-stratosphere-troposphere (MST) radars are reviewed. The designs consist of digital and analog types which resemble filters or correlators in their operation. A new analog design is presented, and a discussion of the choice between hardware and software decoding is given. The number of bits required for digital coherent integrators and decoders is discussed, and the use of fast Fourier transforms for decoding is described.
BibTeX:
@article{Sulzer1985,
  author = {Sulzer, M. P. and Woodman, R. F.},
  title = {Pulse compression hardware decoding techniques for MST radars},
  journal = {Radio Science},
  year = {1985},
  volume = {20},
  number = {6},
  pages = {1146-1154},
  url = {http://dx.doi.org/10.1029/RS020i006p01146},
  doi = {10.1029/RS020i006p01146}
}
Thide B (1985), "Parametric and related non-linear wave-wave interactions in the ionosphere", Journal of Atmospheric and Terrestrial Physics . Vol. 47(12), pp. 1257 - 1265.
Abstract: Six papers all dealing with non-linear wave interaction processes excited during ionospheric modification experiments are reviewed. The papers were presented as posters at the URSI Open Symposium 2 on Active Experiments in Space Piasmas, Florence, Italy, 30–31 August 1984.
BibTeX:
@article{Thide1985,
  author = {Bo Thide},
  title = {Parametric and related non-linear wave-wave interactions in the ionosphere},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1985},
  volume = {47},
  number = {12},
  pages = {1257 - 1265},
  url = {http://www.sciencedirect.com/science/article/pii/0021916985900923},
  doi = {10.1016/0021-9169(85)90092-3}
}
Tsuda T, Hirose K, Kato S and Sulzer MP (1985), "Some findings on correlation between the stratospheric echo power and the wind shear observed by the Arecibo UHF radar", Radio Science. Vol. 20(6), pp. 1503-1508.
Abstract: This paper is concerned with the correlation between the echo power and the wind shear observed on June 10 and 11, 1983, by the Arecibo UHF radar at the altitude of 13–22 km. Correlation values of 0.76 and 0.82 were obtained on each day between the range-corrected echo power and the square of the wind shear for the horizontal wind fields due to both the mean wind and waves with a relatively large vertical scale. The maximum echo intensity occurred at approximately 500 m higher altitude than that of the wind shear. A ratio between the range-corrected echo power and the square of the wind shear averaged in the whole altitude region was similar for observations done on 2 successive days.
BibTeX:
@article{Tsuda1985,
  author = {Tsuda, T. and Hirose, K. and Kato, S. and Sulzer, M. P.},
  title = {Some findings on correlation between the stratospheric echo power and the wind shear observed by the Arecibo UHF radar},
  journal = {Radio Science},
  year = {1985},
  volume = {20},
  number = {6},
  pages = {1503-1508},
  url = {http://dx.doi.org/10.1029/RS020i006p01503},
  doi = {10.1029/RS020i006p01503}
}
Bilitza D (1984), "Comparison between the IRI ion composition and incoherent scatter measurement and theoretical values", Advances in Space Research . Vol. 4(1), pp. 107-109.
BibTeX:
@article{Bilitza1984,
  author = {D. Bilitza},
  title = {Comparison between the IRI ion composition and incoherent scatter measurement and theoretical values},
  journal = {Advances in Space Research },
  year = {1984},
  volume = {4},
  number = {1},
  pages = {107-109},
  doi = {10.1016/0273-1177(84)90481-2}
}
Czechowsky P, Schmidt G and RÝster R (1984), "The mobile SOUSY Doppler radar: Technical design and first results", Radio Science. Vol. 19(1), pp. 441-450.
Abstract: On the basis of the experience obtained with the stationary SOUSY radar in the Harz mountains, a mobile VHF Doppler system was developed during the last two years. The electronic part is installed in a 20-foot container and was tested for the first time during a joint experiment at the Arecibo Observatory (Puerto Rico) using a special log-periodic aerial to illuminate the 300-m dish. In 1982 this system was extended by designing a mobile phased antenna array with 576 Yagi elements. The grouping of the single Yagis, the feeding network, the phase shifters, the power splitters, and the transmit receive switch are described. A summary of results obtained during the first two campaigns is presented as well as a survey of future programs demonstrating the flexibility of this mobile system.
BibTeX:
@article{Czechowsky1984,
  author = {Czechowsky, P. and Schmidt, G. and RÝster, R.},
  title = {The mobile SOUSY Doppler radar: Technical design and first results},
  journal = {Radio Science},
  year = {1984},
  volume = {19},
  number = {1},
  pages = {441-450},
  url = {http://dx.doi.org/10.1029/RS019i001p00441},
  doi = {10.1029/RS019i001p00441}
}
Djuth FT (1984), "HF-enhanced plasma lines in the lower ionosphere", Radio Science. Vol. 19(1), pp. 383-394.
Abstract: The ionospheric modification facility at Arecibo, Puerto Rico, has been used to study Langmuir waves excited in the lower ionosphere by a high-power HF radio wave. Measurements of HF-enhanced plasma lines have been made in the lower F region (< 160 km altitude) and in the E region using the 430-MHz radar at Arecibo Observatory. These measurements complement observations made in the past at higher altitudes. Enhanced plasma line spectra observed in the lower F region peak at the so-called “decay line” and contain additional spectral structure similar to that found in the upper F region. In the E region the spectra exhibit narrow peaks located at 430 MHz ±ƒHF, where ƒHF is the frequency of the modifying HF wave. While strong plasma line enhancements are commonly observed in sporadic E, only weak enhancements have been detected in the normal daytime E layer. Candidate mechanisms for the E region enhancements include the oscillating two-stream instability and direct conversion of the HF wave into Langmuir waves.
BibTeX:
@article{Djuth1984,
  author = {Djuth, F. T.},
  title = {HF-enhanced plasma lines in the lower ionosphere},
  journal = {Radio Science},
  year = {1984},
  volume = {19},
  number = {1},
  pages = {383-394},
  url = {http://dx.doi.org/10.1029/RS019i001p00383},
  doi = {10.1029/RS019i001p00383}
}
Fejer JA, Djuth FT and Gonzales CA (1984), "Bragg backscatter from plasma inhomogeneities due to a powerful ionospherically reflected radio wave", Journal of Geophysical Research: Space Physics. Vol. 89(A10), pp. 9145-9147.
Abstract: Backscatter from quasi-periodic inhomogeneities in the electron density, generated by a powerful ionospherically reflected wave, has been observed at Arecibo. The backscatter was more intense by about 40 dB than that observed earlier by other workers at higher latitudes. It is suggested that the anomalous ionospheric absorption was greater in the earlier experiments.
BibTeX:
@article{Fejer1984,
  author = {Fejer, J. A. and Djuth, F. T. and Gonzales, C. A.},
  title = {Bragg backscatter from plasma inhomogeneities due to a powerful ionospherically reflected radio wave},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1984},
  volume = {89},
  number = {A10},
  pages = {9145-9147},
  url = {http://dx.doi.org/10.1029/JA089iA10p09145},
  doi = {10.1029/JA089iA10p09145}
}
Fejer JA and Sulzer M (1984), "The HF-induced plasma line below threshold", Radio Science. Vol. 19(2), pp. 675-682.
Abstract: Observations at Arecibo of the HF-induced plasma line for low powers of the HF modifying transmitter are described and interpreted. The observed spectra were centered on the radar frequency minus the HF modifying frequency and had the same shape and width as the ion line of incoherent backscatter. The importance of the standing-wave nature of the HF pump wave for such observationsis stressed.
BibTeX:
@article{Fejer1984a,
  author = {Fejer, J. A. and Sulzer, M.},
  title = {The HF-induced plasma line below threshold},
  journal = {Radio Science},
  year = {1984},
  volume = {19},
  number = {2},
  pages = {675-682},
  url = {http://dx.doi.org/10.1029/RS019i002p00675},
  doi = {10.1029/RS019i002p00675}
}
Ferraro A, Lee H, Allshouse R, Carroll K, Lunnen R and Collins T (1984), "Characteristics of ionospheric ELF radiation generated by HF heating", Journal of Atmospheric and Terrestrial Physics. Vol. 46(10), pp. 855-865.
Abstract: This paper describes new observations of the characteristics of ELF generation produced by modulation of the dynamo current system from HF heating of the ionospheric D-region. A model of the ELF antenna structure embedded in the D-region is described and stepped ELF frequency observations are shown to support the model assumptions. Presented are data on the phase height of the ELF ionospheric antenna versus ELF frequency, polarization of the downgoing wave and relationship to the dynamo current direction, correlation of ELF field strength with per cent cross-modulation, power linearity tests and duty cycle results. All observations used the high power heater facility of the Arecibo Observatory.
BibTeX:
@article{Ferraro1984,
  author = {A.J Ferraro and H.S Lee and R Allshouse and K Carroll and R Lunnen and T Collins},
  title = {Characteristics of ionospheric ELF radiation generated by HF heating},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1984},
  volume = {46},
  number = {10},
  pages = {855-865},
  url = {http://www.sciencedirect.com/science/article/pii/0021916984900254},
  doi = {10.1016/0021-9169(84)90025-4}
}
Ganguly S (1984), "Observations of large negative ion zones around 88 km", Journal of Atmospheric and Terrestrial Physics. Vol. 46, pp. 633-666. Elsevier Science.
BibTeX:
@article{Ganguly1984,
  author = {Suman Ganguly},
  title = {Observations of large negative ion zones around 88 km},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  publisher = {Elsevier Science},
  year = {1984},
  volume = {46},
  pages = {633-666},
  doi = {10.1016/0021-9169(84)90126-0}
}
Gonzales CA and Woodman RF (1984), "Pulse compression techniques with application to HF probing of the mesosphere", Radio Science. Vol. 19(3), pp. 871-877.
Abstract: We show that pulse compression techniques which use sets of more than two complementary sequences can be useful in HF radar probing of the D region of the ionosphere. The sets we propose here have an important advantage over the standard complementary pair of codes: they can eliminate E or F region multiple-hop echoes which interfere with D region echoes, when relatively short radar interpulse periods are used. Consequently, both altitude resolution and radar sensitivity can be substantially improved over previous experiments by coding the transmitter pulses and by using shorter interpulse periods. Sets of complementary sequences also perform coherent integration of the received signals and can eliminate the instrumental dc bias. The technique has been tested at Arecibo in an experiment in which we measure the spectra of partially reflected D region echoes. In this experiment, sophisticated processing hardware is used to decode, to perform coherent integration, and to compute-simultaneously and on-line-the spectra of echoes from 256 altitudes in the 0- to 230-km range.
BibTeX:
@article{Gonzales1984,
  author = {Gonzales, Cesar A. and Woodman, Ronald F.},
  title = {Pulse compression techniques with application to HF probing of the mesosphere},
  journal = {Radio Science},
  year = {1984},
  volume = {19},
  number = {3},
  pages = {871-877},
  url = {http://dx.doi.org/10.1029/RS019i003p00871},
  doi = {10.1029/RS019i003p00871}
}
Hagfors T, Birkmayer W and Sulzer M (1984), "A new method for accurate ionospheric electron density measurements by incoherent scatter radar", Journal of Geophysical Research: Space Physics. Vol. 89(A8), pp. 6841-6845.
Abstract: It is shown that the detectability of the plasma line in incoherent scatter radar experiments on the ionospheric plasma can be increased by factors in the range of 10-100 by chirping the transmitter frequency at a rate matching the rate of change of plasma frequency with height. The method is explained in detail, and some initial experiments carried out at the Arecibo Observatory are described. Plasma frequency versus height profiles with an accuracy better than one part in 10¨ were established with 1-s integration time per point. An example of quasi-periodic oscillation of ionospheric electron density with a period of about 18 min is also shown. The chirped frequency observations will greatly facilitate plasma line studies of photoelectrons, allow for studies of small-amplitude wavelike density perturbations, provide electron density profiles with high time resolution and unprecedented accuracy, make it possible to measure electron temperature independently of ion temperature, and probably allow for observations of vertical currents.
BibTeX:
@article{Hagfors1984,
  author = {Hagfors, T. and Birkmayer, W. and Sulzer, M.},
  title = {A new method for accurate ionospheric electron density measurements by incoherent scatter radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1984},
  volume = {89},
  number = {A8},
  pages = {6841-6845},
  url = {http://dx.doi.org/10.1029/JA089iA08p06841},
  doi = {10.1029/JA089iA08p06841}
}
Maekawa Y, Fukao S, Sato T, Kato S and Woodman RF (1984), "Internal Inertia-Gravity Waves in the Tropical Lower Stratosphere Observed by the Arecibo Radar", Journal of the Atmospheric Sciences. Vol. 41(15), pp. 2359-2367.
Abstract: High-resolution upper tropospheric and lower stratospheric (5-30 km) wind data were obtained during three periods from 1979 to 1981 with the aid of the high-power UHF radar at Arecibo, Puerto Rico (18.4°N, 66.8°W). A quasi-periodic wind oscillation with an apparent period of 20-50 h was observed between 16 and 20 km in every experiment. The amplitude of both zonal and meridional wind components was 2 m /s, and the vertical wavelength 2 km. The direction of the wind associated with this oscillation rotated clockwise with time, as seen for inertia-gravity waves in the Northern Hemisphere.
The wave disappeared near 20 km where the mean zonal flow had easterly shear with height. This phenomenon is discussed in terms of wave absorption at a critical level. It is suggested that the, wave had a westward horizontal phase speed of 10-20 m/s. The intrinsic period and the horizontal wavelength at the wave-generated height are inferred to be 20-30 h and 2000 km, respectively, from the relationship based on f-plane theory that the Doppler-shifted wave frequency approaches the Coriolis frequency at the critical level. The vertical group velocity estimated from the dispersion equation on the f-plane closely agrees with the ascending rate of the observed wave packets at each height.
In addition, each observation showed the presence of another type of oscillation with somewhat longer vertical wavelength in the lower stratosphere. If we assume the same intrinsic period and horizontal scale for this oscillation as for the abovementioned smaller vertical-scale wave at the tropopause level, the observed period and vertical structure are well described in terms of an internal inertia-gravity wave propagating to the opposite side in the horizontal plane.
BibTeX:
@article{Maekawa1984,
  author = {Maekawa, Y. and Fukao, S. and Sato, T. and Kato, S. and Woodman, R. F.},
  title = {Internal Inertia-Gravity Waves in the Tropical Lower Stratosphere Observed by the Arecibo Radar},
  journal = {Journal of the Atmospheric Sciences},
  year = {1984},
  volume = {41},
  number = {15},
  pages = {2359-2367},
  url = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281984%29041%3C2359%3AIIWITT%3E2.0.CO%3B2},
  doi = {10.1175/1520-0469(1984)041}
}
Mathews J (1984), "The incoherent scatter radar as a tool for studying the ionospheric D-region", Journal of Atmospheric and Terrestrial Physics . Vol. 46(11), pp. 975 - 986.
Abstract: The theory of the D-region incoherent scatter process and the techniques for incoherent scatter radar measurements in the D-region have both reached sufficient maturity that a synopsis of this area for the middle atmosphere community is appropriate. For example, all current UHF incoherent scatter radars can make useful D-region measurements, at least under some conditions, and the Arecibo 430 MHz radar is being used for a regular program of D-region measurements. Atmospheric and ionospheric parameters which are accessible, to varying degrees, as functions of time and height include electron concentration, ion-neutral collision frequency, neutral atmosphere temperature pressure and winds and mean negative and positive ion masses and concentrations. A qualitative view of the collision dominated incoherent scatter process is given as an aid in understanding the capabilities and limitations of these measurements. Included here is a discussion of some of the issues still surrounding the theory of collision dominated incoherent scattering. Also presented is an overview of data gathering, processing and interpretation techniques, with comments on how total power and power spectrum measurements should be combined to give optimum results. Finally, a comprehensive list of outstanding problems in D-region aeronomy is given, along with suggestions of how incoherent scatter radar along with other MAP measurements can address them. Included in this list are the winter absorption anomaly. D-region ‘ledge’ chemistry and high latitude D-region phenomena.
BibTeX:
@article{Mathews1984,
  author = {J.D Mathews},
  title = {The incoherent scatter radar as a tool for studying the ionospheric D-region},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1984},
  volume = {46},
  number = {11},
  pages = {975 - 986},
  url = {http://www.sciencedirect.com/science/article/pii/0021916984900047},
  doi = {10.1016/0021-9169(84)90004-7}
}
Sulzer MP and Woodman RF (1984), "Quasi-complementary codes: A new technique for MST radar sounding", Radio Science. Vol. 19(1), pp. 337-344.
Abstract: The binary phase complementary code set has been used in stratospheric radar sounding. The quasi-complementary code technique presented here has nearly complementary properties and offers significant reduction of side lobes caused by imperfections in the radar transmitter. The new technique and its application are described; a simulation of the performance of the two techniques when certain imperfections are present in the transmitter is presented. The results are compared with the actual performance of the Arecibo 430-MHz radar transmitter.
BibTeX:
@article{Sulzer1984,
  author = {Sulzer, M. P. and Woodman, R. F.},
  title = {Quasi-complementary codes: A new technique for MST radar sounding},
  journal = {Radio Science},
  year = {1984},
  volume = {19},
  number = {1},
  pages = {337-344},
  url = {http://dx.doi.org/10.1029/RS019i001p00337},
  doi = {10.1029/RS019i001p00337}
}
Tepley C, Burnside R, Jr. JM, Hays P and Cogger L (1984), "Spatial mapping of the thermospheric neutral wind field ", Planetary and Space Science . Vol. 32(4), pp. 493-501.
Abstract: There are many possible observing strategies available for mapping the thermospheric wind field by using observations of the Doppler shift of the O (1D) airglow with a Fabry-Perot interferometer. The determination of the neutral wind field from observed line-of-sight velocities invariably involves some assumptions about the nature of the wind field. A standard method of observing employs the assumption that horizontal gradients in the wind field are linear. An analysis of measurements from Arecibo, Puerto Rico, that makes use of this assumption, is discussed. For work at high latitudes this assumption may be unrealistic. An alternative approach that requires that local time and longitude be interchangeable, but eschews the assumption of linear gradients has been developed and used at Ann Arbor, Michigan, and Calgary, Alberta. We examine these different techniques, and illustrate the discussion with some typical results.
BibTeX:
@article{Tepley1984,
  author = {C.A. Tepley and R.G. Burnside and J.W. Meriwether Jr. and P.B. Hays and L.L. Cogger},
  title = {Spatial mapping of the thermospheric neutral wind field },
  journal = {Planetary and Space Science },
  year = {1984},
  volume = {32},
  number = {4},
  pages = {493-501},
  url = {http://www.sciencedirect.com/science/article/pii/0032063384901284},
  doi = {10.1016/0032-0633(84)90128-4}
}
Abreu V, Schmitt G, Hays P, Jr. JM, Tepley C and Cogger L (1983), "Atmospheric scattering effects on ground-based measurements of thermospheric winds", Planetary and Space Science . Vol. 31(3), pp. 303-310.
Abstract: Inherent in observations of thermospheric winds from the ground with the Fabry-Perot interferometer is the assumption that the measured Doppler shift is a property of the source medium viewed by the instrumental line of sight. However, ground based airglow observations in regions of weak airglow emission near large intensity gradients may be contaminated by scattered light. Light from areas where the emission is strong can be scattered by the lower atmosphere into the field of view of the observations. Thermospheric winds deduced from the observed Doppler shifts will then show apparent convergence or divergence with respect to the site of observation. Examples of this effect are found in observations by the Michigan Airglow Observatory station located near the auroral zone at Calgary, Alberta. Simulation calculations based upon an experimental model for a significant scattering atmosphere also showed results with either convergence or divergence in the apparent neutral wind field observed by the station.
BibTeX:
@article{Abreu1983,
  author = {V.J. Abreu and G.A. Schmitt and P.B. Hays and J.W. Meriwether Jr. and C.A. Tepley and L.L. Cogger},
  title = {Atmospheric scattering effects on ground-based measurements of thermospheric winds},
  journal = {Planetary and Space Science },
  year = {1983},
  volume = {31},
  number = {3},
  pages = {303-310},
  url = {http://dx.doi.org/10.1016/0032-0633(83)90080-6},
  doi = {10.1016/0032-0633(83)90080-6}
}
Bailey G (1983), "The effect of a meridional ExB drift on the thermal plasma at L = 1.4", Planetary and Space Science . Vol. 31(4), pp. 389-409.
Abstract: A fully time dependent mathematical model of the thermal plasma at L = 1.4 is described. In the mathematical model account is taken of a quiet-time E â B drift in the meridional plane. Atmospheric conditions appropriate to equinox at sunspot minimum and at sunspot maximum are considered. Results of the model calculations are presented. Emphasis is placed on the effects on the thermal plasma of a quiet-time E â B drift in the meridional plane. A comparison of the model calculations which include an E â B drift with those in which there is no E â B drift shows than an E â B drift significantly affects the plasma concentration and temperature distributions during the day at both sunspot minimum and sunspot maximum; the effects at night are very small. An upward E â B drift during the day increases both NmF2 and hmF2 and decreases the plasma temperature. The decrease in plasma temperature is due primarily to the increase in plasma concentration. It is more pronounced in the electron temperature than in the ion temperature and it varies considerably with altitude, time and atmospheric conditions. The changes in plasma concentration and temperature brought about by an E â B drift also change the O+-H+ transition height and the O+ and H+ tube contents. For the E â B drifts considered the O+-H+ transition height is raised during the morning and lowered during the afternoon. The changes in O+ tube content roughly follow the changes in NmF2. The changes in H+ tube content, however, are small since the H+ tube content is controlled by the H+ concentration at the higher altitudes of the tube of plasma and these concentration values are only slightly affected by the E â B drifts considered.
BibTeX:
@article{Bailey1983,
  author = {G.J. Bailey},
  title = {The effect of a meridional ExB drift on the thermal plasma at L = 1.4},
  journal = {Planetary and Space Science },
  year = {1983},
  volume = {31},
  number = {4},
  pages = {389-409},
  url = {http://dx.doi.org/10.1016/0032-0633(83)90154-X},
  doi = {10.1016/0032-0633(83)90154-X}
}
Basu S, Basu S, Ganguly S and Gordon WE (1983), "Coordinated study of subkilometer and 3-m irregularities in the F region generated by high-power HF heating at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 88(A11), pp. 9217-9225.
Abstract: High-power high-frequency transmitters near Arecibo were used to generate artificial ionospheric irregularities in the F region. Radio star scintillation observations at 430 MHz were performed at Arecibo Ionospheric Observatory with the 305-m antenna, and radar backscatter measurements at 50 MHz were simultaneously made from Guadeloupe Island to probe the subkilometer and 3-m irregularities in the heated volume. Scintillation studies indicate a low-frequency modulation of the faster intensity fluctuation structure. By the use of plasma drift data this low-frequency temporal structure translates to spatial dimensions of 1–2 km. The frequency of the modulation envelope is found to be controlled by the heater power and is related to the dominant irregularity wavelength generated by the self-focusing instability. Scintillation spectra imply a steep power law index of ?5 in the scale length range of about 300 m to 150 m and a shallow index of ?2 at less than 150 m. The steep power law index may arise from an aperture averaging effect of the large 305-m antenna at Arecibo. Simultaneous measurements of 430-MHz scintillations and 50-MHz radar backscatter from field-aligned striations were performed to show that subkilometer irregularities can be generated by both O and X mode heating whereas the 3-m irregularities are excited only by the O mode heating, as is predicted by the theories of self-focusing and parametric instability. The width of the 50-MHz echo Doppler spectra is observed to be very narrow, only ?2–3 Hz, and independent of the background plasma drift, implying that the frequency bandwidth of the scattered signal is probably controlled by the instability process.
BibTeX:
@article{Basu1983,
  author = {Basu, Santimay and Basu, Sunanda and Ganguly, S. and Gordon, W. E.},
  title = {Coordinated study of subkilometer and 3-m irregularities in the F region generated by high-power HF heating at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A11},
  pages = {9217-9225},
  url = {http://dx.doi.org/10.1029/JA088iA11p09217},
  doi = {10.1029/JA088iA11p09217}
}
Burnside RG, Behnke RA and Walker JCG (1983), "Meridional neutral winds in the thermosphere at Arecibo: Simultaneous incoherent scatter and airglow observations", Journal of Geophysical Research: Space Physics. Vol. 88(A4), pp. 3181-3189.
Abstract: Simultaneous measurements of ion and neutral wind velocities have been obtained at Arecibo, Puerto Rico, on several nights in both the summer and winter seasons. The diffusion velocity of O+, calculated in an analysis by using the accepted value for the ambipolar diffusion coefficient and the MSIS model atmosphere, is found to be in fairly close agreement with the observations. Incoherent scatter radar data have also been used to derive height profiles of the meridional neutral wind velocity. In the spring and summer months, the meridional wind is strongest near 2100 AST, with a southward velocity ranging from 50-100 m s-1. At about 0100 AST the ‘midnight descent’ of the F layer occurs, in association with a slackening, or sometimes a reversal, of the meridional wind. In general, the meridional wind is fairly constant with altitude. However, prior to midnight in the spring and summer months, contours of constant velocity are often observed to slope downward with increasing time. Some degree of vertical wind shear is often observed between 0200 and 0500 AST as well. In the winter months, meridional wind velocities are lower, and the nocturnal variation of the wind field is less pronounced than it is at other seasons.
BibTeX:
@article{Burnside1983,
  author = {Burnside, R. G. and Behnke, R. A. and Walker, J. C. G.},
  title = {Meridional neutral winds in the thermosphere at Arecibo: Simultaneous incoherent scatter and airglow observations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A4},
  pages = {3181-3189},
  url = {http://dx.doi.org/10.1029/JA088iA04p03181},
  doi = {10.1029/JA088iA04p03181}
}
Burnside RG, Walker JCG, Behnke RA and Gonzales CA (1983), "Polarization electric fields in the nighttime F layer at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 88(A8), pp. 6259-6266.
Abstract: Incoherent scatter radar measurements made in 1981 and 1982 are used to determine the electrical conductivity of the nighttime E and F regions at Arecibo, Puerto Rico. The height-integrated Pedersen conductivity of the F region exceeds that of the E region by a factor of 10 on the average. We therefore conclude that, for the solar maximum conditions we have studied, the local E region has little influence on nighttime F region electrodynamics. Simultaneous measurements of ion and neutral velocities are often inconsistent with the hypothesis that a fully developed electric polarization field is generated by dynamo action in the local F region. A better explanation of our results is obtained by including the influence of polarization fields that originate in the F region of the conjugate hemisphere.
BibTeX:
@article{Burnside1983a,
  author = {Burnside, R. G. and Walker, J. C. G. and Behnke, R. A. and Gonzales, C. A.},
  title = {Polarization electric fields in the nighttime F layer at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A8},
  pages = {6259-6266},
  url = {http://dx.doi.org/10.1029/JA088iA08p06259},
  doi = {10.1029/JA088iA08p06259}
}
Farley DT, LaHoz C and Fejer BG (1983), "Studies of the self-focusing instability at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 88(A3), pp. 2093-2102.
Abstract: Precisely simultaneous radar and satellite measurements at the altitude of reflection of a strong HF heating wave above the Arecibo Observatory were made on June 7, 1977. Parametric instabilities produce strong enhancements in the plasma line and ion line incoherent scatter radar echoes. These echoes also exhibit periodic deep fading that is attributed to a self-focusing instability. This explanation was confirmed by the in situ observation of electron density fluctuations with peak-to-peak amplitudes reaching at least 3% and a spatial dependence that corresponded closely to the radar fading pattern, at least for irregularity wavelengths ranging from a few hundred meters to a few kilometers. The correspondence implies that the radar fading is associated with the convection of the density irregularities through the radar beam. The radar and satellite observations also provided values for the important parameters of the ambient ionosphere, making possible a quantitative comparison of the data with existing theories of the self-focusing instability. In particular, the agreement with the theory of Cragin et al. (1977) is fairly good.
BibTeX:
@article{Farley1983,
  author = {Farley, Donald T. and LaHoz, Cesar and Fejer, Bela G.},
  title = {Studies of the self-focusing instability at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A3},
  pages = {2093-2102},
  url = {http://dx.doi.org/10.1029/JA088iA03p02093},
  doi = {10.1029/JA088iA03p02093}
}
Fejer JA, Ierkic HM, Woodman RF, Rottger J, Sulzer M, Behnke RA and Veldhuis A (1983), "Observations of the HF-enhanced plasma line with a 46.8-MHz Radar and reinterpretation of previous observations with the 430-MHz radar", Journal of Geophysical Research: Space Physics. Vol. 88(A3), pp. 2083-2092.
Abstract: During 5.1-MHz HF transmissions below the F region penetration frequency by a nearby ionospheric modification facility, radar echoes coming from F region heights at a frequency of 46.8 + 5.1 = 51.9 MHz were received while a VHF radar using the 305 m spherical reflector at Arecibo was transmitting pulses coherently on 46.8 MHz. The bandwidth of the echoes was less than 10 Hz. The so-called decay line due to the parametric decay instability was expected at a frequency lower by about 300 Hz, but it was not observed. Density variations caused by the ponderomotive force resulting from the standing wave pattern at 5.1 MHz are tentatively invoked to explain the observations. Poorly understood aspects of some previous observations with the 430-MHz radar can be similarly explained.
BibTeX:
@article{Fejer1983,
  author = {Fejer, J. A. and Ierkic, H. M. and Woodman, R. F. and Rottger, J. and Sulzer, M. and Behnke, R. A. and Veldhuis, A.},
  title = {Observations of the HF-enhanced plasma line with a 46.8-MHz Radar and reinterpretation of previous observations with the 430-MHz radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A3},
  pages = {2083-2092},
  url = {http://dx.doi.org/10.1029/JA088iA03p02083},
  doi = {10.1029/JA088iA03p02083}
}
Gonzales CA, Kelley MC, Behnke RA, Vickrey JF, Wand R and Holt J (1983), "On the latitudinal variations of the ionospheric electric field during magnetospheric disturbances", Journal of Geophysical Research: Space Physics. Vol. 88(A11), pp. 9135-9144.
Abstract: A joint alert campaign was organized during the month of October 1980 by the incoherent scatter radars in the American sector: namely, Jicamarca, Arecibo, Millstone Hill, and Chatanika. The campaign, which met with success, was designed to study the behavior of the ionospheric electric field as a function of latitude during magnetically active conditions. The Arecibo data in this campaign support present and previous observations at Jicamarca that suggest that when the convection E field suddenly decreases, the AlfvÈn layer shielding field becomes unbalanced and penetrates the plasmasphere. While this type of observation is reasonably convincing, others are more difficult to categorize. We suggest that, beside the high-latitude electric fields, time-varying auroral conductivity models will have to be considered in order to understand the morphology of the low-latitude E field disturbances. We present the first correlation analysis and determination of the amplitude ratio of the disturbed zonal electric field at 30° geometric latitude (Arecibo) to the field at 0° (Jicamarca). Other highlights of the paper are a discussion of DP2, which may help clarify the controversy surrounding it, and a discussion of the sensitivity of low- and mid-latitude radars to disturbances of magnetospheric origin. We show that this sensitivity maximizes at the magnetic equator.
BibTeX:
@article{Gonzales1983,
  author = {Gonzales, C. A. and Kelley, M. C. and Behnke, R. A. and Vickrey, J. F. and Wand, R. and Holt, J.},
  title = {On the latitudinal variations of the ionospheric electric field during magnetospheric disturbances},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1983},
  volume = {88},
  number = {A11},
  pages = {9135-9144},
  url = {http://dx.doi.org/10.1029/JA088iA11p09135},
  doi = {10.1029/JA088iA11p09135}
}
Hirota I, Maekawa Y, Fukao S, Fukuyama K, Sulzer MP, Fellous JL, Tsuda T and Kato S (1983), "Fifteen-day observation of mesospheric and lower thermospheric motions with the aid of the Arecibo UHF radar", Journal of Geophysical Research: Oceans. Vol. 88(C11), pp. 6835-6842.
Abstract: An attempt was made to have a continuous observation of the zonal wind component in the tropical mesosphere and lower thermosphere for 15 days of August 1–15, 1980, with the aid of the UHF radar at Arecibo (18°N). By using the wind data, together with additional data obtained from meteorological rockets, meteor radar, and Tiros-N satellite, analyses were made of the time-mean zonal wind profile, tides, long-period waves, and short-period gravity-type waves, respectively. There appears a remarkable day-to-day variation of the zonal wind throughout the region between 70 and 95 km with a characteristic time scale of about 5 days, indicating the passage of traveling planetary-scale waves in the summertime tropical middle atmosphere. It was also found that the short-period oscillation with a time scale of a few 10 min appears intermittently in association with the strong vertical shear of the background flow. This oscillation is considered to be the manifestation of the Kelvin-Helmholtz type instability in the lower thermosphere.
BibTeX:
@article{Hirota1983,
  author = {Hirota, I. and Maekawa, Y. and Fukao, S. and Fukuyama, K. and Sulzer, M. P. and Fellous, J. L. and Tsuda, T. and Kato, S.},
  title = {Fifteen-day observation of mesospheric and lower thermospheric motions with the aid of the Arecibo UHF radar},
  journal = {Journal of Geophysical Research: Oceans},
  year = {1983},
  volume = {88},
  number = {C11},
  pages = {6835-6842},
  url = {http://dx.doi.org/10.1029/JC088iC11p06835},
  doi = {10.1029/JC088iC11p06835}
}
Royrvik O (1983), "Midlatitude sporadic-E layers and vertical metallic ion drift profiles ", Planetary and Space Science. Vol. 31(2), pp. 253-264.
Abstract: An investigation of the relationship between the occurrence of midlatitude sporadic-E layers and convergent points in the ion drift profiles has been made using the 430 MHz incoherent scatter radar at the Arecibo Observatory. Electron concentration profiles were obtained using a 13 baud Barker coded pulse yielding 600 m range resolution, while a 5-pulse sequence with 2.4 km range resolution was used to obtain line-of-sight ion drift velocities. With some exceptions, observed sporadic-E layers occur near convergent points in the vertical metallic ion drift profile, and vertical motions of these layers follow the vertical motions of the convergent point.

Vertical motions and intensity variations of observed sporadic-E layers are due to interaction between the mean wind, tidal waves, and gravity waves of different periods producing a predominantly downward motion of the layer. However, a sudden increase in the altitude of a sporadic-E layer has been observed. This is attributed to the disappearance of the convergent point—releasing the layer—followed by an ascent of the layer to the closest overlying convergent point.

BibTeX:
@article{Royrvik1983,
  author = {O. Royrvik},
  title = {Midlatitude sporadic-E layers and vertical metallic ion drift profiles },
  journal = {Planetary and Space Science},
  year = {1983},
  volume = {31},
  number = {2},
  pages = {253-264},
  url = {http://www.sciencedirect.com/science/article/pii/0032063383900600},
  doi = {10.1016/0032-0633(83)90060-0}
}
Zamlutti C (1983), "Incoherent scatter observations of mid-latitude sporadic-E and comments on its data analysis", Journal of Atmospheric and Terrestrial Physics. Vol. 45, pp. 79-87.
Abstract: Incoherent scatter observations of sporadic-E have been reported from measurements at Arecibo (18.3°N) in the last decade. Some important results have been achieved. They are examined here as a source for improving the Es study. Critical aspects of experiment design and data analysis are also considered for further experiments.
BibTeX:
@article{Zamlutti1983,
  author = {C.J. Zamlutti},
  title = {Incoherent scatter observations of mid-latitude sporadic-E and comments on its data analysis},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1983},
  volume = {45},
  pages = {79-87},
  url = {http://www.sciencedirect.com/science/article/pii/S0021916983800129},
  doi = {10.1016/S0021-9169(83)80012-9}
}
Bailey GJ, Vickrey JF and Swartz WE (1982), "The topside ionosphere above Arecibo during summer at sunspot minimum and the influence of an interhemispheric flow of thermal protons", Journal of Geophysical Research: Space Physics. Vol. 87(A9), pp. 7557-7567.
Abstract: Incoherent scatter measurements of the topside ionosphere above Arecibo on August 15–16, 1976, are presented and compared with a time-dependent mathematical model of the L = 1.4 magnetic flux tube. In the mathematical model the ions are O+ and H+, and their concentrations and field-aligned velocities are calculated from time dependent plasma continuity and momentum equations. As far as possible, the values of the atmospheric parameters used in the mathematical model are appropriate to August 15–16, 1976. However, to help explain the processes that occur in the topside ionosphere above Arecibo, calculations have been performed with some modified atmospheric parameters. The observed values of electron concentration and percentage H+ abundance can be reproduced by the mathematical model if we permit an interhemispheric flow of H+. There does not appear to be any other physically realistic way to achieve agreement. At times, the model indicates that interhemispheric flow of H+ is from the hemisphere conjugate to Arecibo, i.e., from the winter hemisphere to the summer hemisphere. However, the results of the calculations suggest a net 24-hour transfer of H+ into the conjugate hemisphere, i.e., from the summer hemisphere to the winter hemisphere. Typically, it amounts to 55% of the 24-hour mean value of the total plasma content of the L = 1.4 magnetic flux tube between an altitude of 963 km and the equatorial plane. This is in excellent agreement with the estimate of net integrated H+ flux given by Vickrey et al. (1979b), which was based on comparing Arecibo observations from summer and winter days. However, the model indicates that there is no simple relationship on a moment-by-moment basis between the magnitude and direction of the interhemispheric H+ flux and the magnitude and direction of the H+ field-aligned flux at an altitude around 1000 km. We also show that provided the plasma concentration remains unchanged at F2-region altitudes, the concentration of H+ in the topside ionosphere is more sensitive to changes in the neutral atomic hydrogen concentration, n(H), than to changes in the neutral atomic oxygen concentration. However, the concentration of O+ in the topside ionosphere is only marginally affected by n(H).
BibTeX:
@article{Bailey1982,
  author = {Bailey, G. J. and Vickrey, J. F. and Swartz, W. E.},
  title = {The topside ionosphere above Arecibo during summer at sunspot minimum and the influence of an interhemispheric flow of thermal protons},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1982},
  volume = {87},
  number = {A9},
  pages = {7557-7567},
  url = {http://dx.doi.org/10.1029/JA087iA09p07557},
  doi = {10.1029/JA087iA09p07557}
}
Bilitza D (1982), "New descriptive temperature model", Advances in Space Research . Vol. 2(10), pp. 237-245.
BibTeX:
@article{Bilitza1982,
  author = {D. Bilitza},
  title = {New descriptive temperature model},
  journal = {Advances in Space Research },
  year = {1982},
  volume = {2},
  number = {10},
  pages = {237-245},
  doi = {10.1016/0273-1177(82)90398-2}
}
Blanc E (1982), "Neutral temperature and electron-density measurements in the lower E region by vertical HF sounding in the presence of an acoustic wave", Geophysical Research Letters. Vol. 9(4), pp. 450-453.
BibTeX:
@article{Blanc1982,
  author = {Blanc, Elisabeth},
  title = {Neutral temperature and electron-density measurements in the lower E region by vertical HF sounding in the presence of an acoustic wave},
  journal = {Geophysical Research Letters},
  year = {1982},
  volume = {9},
  number = {4},
  pages = {450-453},
  doi = {10.1029/GL009i004p00450}
}
Breakall JK and Mathews JD (1982), "A theoretical and experimental investigation of antenna near-field effects as applied to incoherent backscatter measurements at Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 44(5), pp. {449-454}.
BibTeX:
@article{Breakall1982,
  author = {Breakall, J K and Mathews, J D},
  title = {A theoretical and experimental investigation of antenna near-field effects as applied to incoherent backscatter measurements at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  number = {5},
  pages = {449-454},
  doi = {10.1016/0021-9169(82)90051-4}
}
Carlson H, Wickwar V and Mantas G (1982), "Observations of fluxes of suprathermal electrons accelerated by HF excited instabilities", Journal of Atmospheric and Terrestrial Physics. Vol. 44(12), pp. 1089-1100.
Abstract: When sufficiently high power o-mode HF radio waves are transmitted at frequencies below the ionospheric maximum plasma frequency, not only are plasma instabilities excited, but ambient electrons are accelerated to energies of several electron volts (vs electron thermal energies of order 0.1 eV). Such fluxes have been experimentally inferred from enhancements of atomic oxygen 6300 å, and occasionally 5577 å airglow emission. Active theoretical work has led to conflicting theories for the basic electron acceleration mechanism responsible. We report here the most direct observations to date of such suprathermal electrons. During experiments at Arecibo, transmitting about 140 kW of o-mode power at 7.63 MHz, near but below the ƒ0F2 (exciting strong plasma wave instabilities near an altitude of 285 km) nighttime plasma line intensities were observed to be enhanced by a factor of 10–100. These enhancements extend over a much broader altitude range than that to which HF excited plasma instabilities are confined. When the transmitter was turned off, these plasma line intensities immediately relaxed to their thermal level. Data are presented which should help guide future theoretical development. One significant conclusion that the observations directly lead to is that electrons are accelerated up to at least 20 eV, an energy so high as to call for reassessment of existing published theories. The data also contradict a highly sensitive HF power dependence of the suprathermal electron flux. The production rate is relatively flat from 10 to 20 eV and relatively stable over several hours for constant HF power densities. Model calculations demonstrate that the observed altitude variation of the plasma line intensities is dominated by collisional energy degradation of the suprathermal electron flux to the neutral atmosphere and ionospheric plasma. The modeling also demonstrates that a valid treatment of the plasma physics involved must include some of the geophysical processes (e.g. scattering by the neutral atmosphere).
BibTeX:
@article{Carlson1982,
  author = {H.C. Carlson and V.B. Wickwar and G.P. Mantas},
  title = {Observations of fluxes of suprathermal electrons accelerated by HF excited instabilities},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  number = {12},
  pages = {1089-1100},
  url = {http://www.sciencedirect.com/science/article/pii/0021916982900204},
  doi = {10.1016/0021-9169(82)90020-4}
}
Carlson HC and Mantas GP (1982), "An experimental test of the ionosphere electron gas cooling rate by excitation of the fine structure of the ground state of atomic oxygen", Journal of Geophysical Research: Space Physics. Vol. 87(A6), pp. 4515-4524.
Abstract: Excitation of the fine structure levels of the ground state of atomic oxygen, O (¨P), is currently believed to be the dominant cooling mechanism for the electron gas of the bottomside ionosphere (roughly, below 250 km). Recent refinements in theoretical excitation cross section calculations have reduced its magnitude by about a factor of 3. This cooling rate, however, has never been measured. The work reported here presents the results of the first experiment designed to measure this cooling rate. The technique is to measure the time relaxation rate of the temperature of the lower F region electron gas, after it is artifically heated by radio waves from a ground-based high-power HF transmitter. The experimental measurements presented favor the cooling rate corresponding to the lowest of the currently available theoretical excitation cross sections. The measurements do not, however, exclude the possibility that even this rate might still be too high by a considerable factor.
BibTeX:
@article{Carlson1982a,
  author = {Carlson, Herbert C. and Mantas, George P.},
  title = {An experimental test of the ionosphere electron gas cooling rate by excitation of the fine structure of the ground state of atomic oxygen},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1982},
  volume = {87},
  number = {A6},
  pages = {4515-4524},
  url = {http://dx.doi.org/10.1029/JA087iA06p04515},
  doi = {10.1029/JA087iA06p04515}
}
Carlson HC and Sundararaman N (1982), "Real-Time Jetstream Tracking: National Benefit from an ST Radar Network for Measuring Atmospheric Motions", Bulletin of the American Meteorological Society. Vol. 63, pp. 1019-1027.
Abstract: Attention is directed to a wind measurement system that could be of significant cost benefit to the airline industry and the nation. A network of Stratosphere-Troposphere (ST) radars can provide continuous wind measurements through the troposphere and lower stratosphere with resolutions of 0.5 to 1.0 km in altitude and a fraction of an hour in time.
United States air carriers consume in excess of 37 billion liters of fuel per year. Existing estimates by other workers indicate 1–3% savings in fuel costs are possible, given accurate and timely knowledge of the location of the atmospheric jet stream, which would allow for optimal use of this variable tail wind (or avoidance of unnecessary head winds). Current and readily available technology can provide an ST radar network with fine spatial resolution capable of continuous real-time jetstream monitoring across the continental United States. The cost of such a network should be recovered in less than one year, if the potential savings indicated were realized. Thus establishment of an ST radar network deserves serious consideration, and it is important to obtain firmer fuel cost savings figures to determine cost effectiveness. The system also would serve other practical and basic research needs in the atmospheric sciences.
BibTeX:
@article{Carlson1982c,
  author = {Herbert C. Carlson and N. Sundararaman},
  title = {Real-Time Jetstream Tracking: National Benefit from an ST Radar Network for Measuring Atmospheric Motions},
  journal = {Bulletin of the American Meteorological Society},
  year = {1982},
  volume = {63},
  pages = {1019-1027},
  url = {http://dx.doi.org/10.1175/1520-0477(1982)063<1019:RTJTNB>2.0.CO;2}
}
Coco D and Ganguly S (1982), "Heating at 430 MHz in the lower ionosphere at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 87(A9), pp. 7551-7556.
Abstract: The 430-MHz radar at Arecibo has been used both to produce and to measure electron temperature increases in the lower ionosphere. The 430-MHz transmitter produced heating pulses from 0.2 to 6.0 ms in length having a maximum power flux of 12 W/m² at 100 km. For the first time, both the spectrum and the total power of the incoherent scatter signals were used to measure the electron temperature increases in the 65 to 110-km altitude region. When the measured electron temperature increases are compared to the results of an ohmic heating model, measured increases are found to be significantly smaller than the predicted increases. Possible explanations for this lack of agreement, such as a non-Maxwellian electron temperature distribution or increased electron cooling rates, are discussed.
BibTeX:
@article{Coco1982,
  author = {Coco, D. and Ganguly, S.},
  title = {Heating at 430 MHz in the lower ionosphere at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1982},
  volume = {87},
  number = {A9},
  pages = {7551-7556},
  url = {http://dx.doi.org/10.1029/JA087iA09p07551},
  doi = {10.1029/JA087iA09p07551}
}
Duncan L and Gordon W (1982), "Ionospheric modification by high power radio waves", Journal of Atmospheric and Terrestrial Physics . Vol. 44(12), pp. 1009-1017.
BibTeX:
@article{Duncan1982,
  author = {L.M. Duncan and W.E. Gordon},
  title = {Ionospheric modification by high power radio waves},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1982},
  volume = {44},
  number = {12},
  pages = {1009-1017},
  doi = {10.1016/0021-9169(82)90013-7}
}
Ferraro A, Lee H, Allshouse R, Carroll K, Tomko A, kelly null F and Joiner R (1982), "VLF/ELF radiation from the ionospheric dynamo current system modulated by powerful HF signals", Journal of Atmospheric and Terrestrial Physics. Vol. 44(12), pp. 1113-1122.
Abstract: This paper presents results of several campaigns at the Arecibo Observatory using the new HF high power ‘heater’ facility. The specific measurement pertains to detecting VLF/ELF radiation from the ionospheric dynamo current system that has been periodically modified by pulsing the HF high power transmitter at VLF or ELF. Because of the nonlinear relationship between ionospheric conductivities and electron temperature, the high power HF source can produce modification of the ionospheric conductivities and consequently of the dynamo current system. That this effect indeed does occur is verified by detecting the VLF/ELF radiation from this current source. Most of the data presented in this paper are concerned with measurements made at ground level beneath the modified current region. Limited data are presented for ELF signals received in Pennsylvania, U.S.A., over a long path from the HF ‘heater’ facility at TromsÜ, Norway.
BibTeX:
@article{Ferraro1982,
  author = {A.J. Ferraro and H.S. Lee and R. Allshouse and K. Carroll and A.A. Tomko and F.J. kelly and R.G. Joiner},
  title = {VLF/ELF radiation from the ionospheric dynamo current system modulated by powerful HF signals},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  number = {12},
  pages = {1113-1122},
  url = {http://www.sciencedirect.com/science/article/pii/0021916982900228},
  doi = {10.1016/0021-9169(82)90022-8}
}
Frey A and Gordon W (1982), "HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations", Journal of Atmospheric and Terrestrial Physics. Vol. 44(12), pp. 1101-1111.
Abstract: High frequency waves incident on an overdense ionosphere (i.e. HF < penetration frequency) are known to produce large-scale irregularities with scale sizes of several hundred meters in the F-region of the ionosphere. Three observations of radio star intensity fluctuations at UHF are reported for HF ionospheric modification experiments performed at the Arecibo Observatory. Two observations at 430 MHz and one observation at 1400 MHz indicate that the thin phase screen theory is a good approximation to the observed power spectra. However, the theory has to be extended to include antenna filtering. Such filtering is important for UHF radio star scintillations since the antenna usually has a narrow beam width. HF power densities of less than 37uW m-2 incident on the ionosphere produce electron density irregularities larger than 13% of the ambient density (at 260 km) having scale sizes of ~510 m perpendicular to the geomagnetic field. The irregularities form within 20-25 s after the HF power is turned on. From the observed power spectra driftvelocities of the irregularities can be estimated.
BibTeX:
@article{Frey1982,
  author = {A Frey and W.E Gordon},
  title = {HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  number = {12},
  pages = {1101-1111},
  url = {http://www.sciencedirect.com/science/article/pii/0021916982900216},
  doi = {10.1016/0021-9169(82)90021-6}
}
Friedman JF and Herrero FA (1982), "Fabry-Perot interferometer measurements of thermospheric neutral wind gradients and reversals at Arecibo", Geophysical Research Letters. Vol. 9(7), pp. 785-788.
Abstract: Direct measurements of the meridional neutral winds in the thermosphere with the Arecibo Observatory Fabry-Perot Interferometer show the post-midnight meridional wind reversal that was inferred from previous incoherent scatter radar ion-drift data and airglow intensity maps, and observed in-situ with the Atmosphere Explorer-E satellite NATE experiment. Data are shown for three nights between October 29 and December 9, 1981. For this period, the meridional wind is observed to be northward after sunset, turning southward before midnight with velocities which often exceed 100 m/sec, and after midnight its direction reverses to northward for one to two hours. The post-midnight reversal is recurrent, and propagates from the equator, as predicted ort the basis of previous meridional airglow intensity measurements. On some nights the reversal is observed only to the south of Arecibo. In those cases it is possible to measure the wind velocity gradient which is set up by the convergent flow. The night of 29/30 October 1981 shows a gradient of about (0.3m/s)/km associated with the reversal (00-0100 LT). Two hours later (0300 LT) an equatorward propagating disturbance with speed of propagation of about 700 m/s is observed. The gradients associated with the disturbance and with the reversal are of the same order of magnitude, giving changes of more than 150 m/sec in a horizontal distance of 500 km. The velocity gradient changes direction as a consequence of the passage of the disturbance. The simultaneous meridional airglow intensity distributions follow the direction of the velocity gradient.
BibTeX:
@article{Friedman1982,
  author = {Friedman, J. F. and Herrero, F. A.},
  title = {Fabry-Perot interferometer measurements of thermospheric neutral wind gradients and reversals at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1982},
  volume = {9},
  number = {7},
  pages = {785-788},
  url = {http://dx.doi.org/10.1029/GL009i007p00785},
  doi = {10.1029/GL009i007p00785}
}
Fukao S, Sato T, Yamasaki N, Harper RM and Kato S (1982), "Winds Measured by a UHF Doppler Radar and Rawinsondes: Comparisons Made on Twenty-Six Days (August-September 1977) at Arecibo, Puerto Rico", Journal of Applied Meteorology. Vol. 21, pp. 1357-1363.
Abstract: Vertical profiles of horizontal winds in the lower stratosphere and upper troposphere were measured by the UHF Doppler radar at Arecibo, Puerto Rico (18.35°N, 66.75°W) on 26 days in August and September 1977. On comparing these with horizontal winds measured by routine rawinsonde balloons launched some 80 km east of Arecibo, fairly good agreement between every wind profile can be seen. Most of the difference between the two sets of measurements in the lower stratosphere is shown to be caused by the experimental error of the rawinsonde, while the spatial and/or temporal variations in the wind field seem to dominate the difference in the upper troposphere.
BibTeX:
@article{Fukao1982,
  author = {Shoichiro Fukao and Toru Sato and Norikazu Yamasaki and Robert M. Harper and Susumu Kato},
  title = {Winds Measured by a UHF Doppler Radar and Rawinsondes: Comparisons Made on Twenty-Six Days (August-September 1977) at Arecibo, Puerto Rico},
  journal = {Journal of Applied Meteorology},
  year = {1982},
  volume = {21},
  pages = {1357-1363},
  url = {http://dx.doi.org/10.1175/1520-0450(1982)021<1357:WMBAUD>2.0.CO;2}
}
Ganguly S and Behnke RA (1982), "Short-period fluctuations in F region ionization observed at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 87(A1), pp. 261-264.
Abstract: Small fluctuations in the critical frequency of the F region plasma have been measured at Arecibo with frequency resolution better than 1 kHz and time resolution of 1 s. For periods in the 10- to 20-min range, f0F2 fluctuations fall off with fluctuation frequency (f) as f-k, with k >= 4.5. While no oscillation is observed in the period range 4–8 min, significant oscillations with amplitude of Df0F2 ~ 500 Hz are observed with a period of T~3 min, corresponding to a fractional change in number density of 1–2 parts in 104. Several possible sources of these fluctuations are explored: acoustic waves in the F region, hydromagnetic or Alfven-type oscillations, and small and large scale electric field fluctuations. Coordinated experiments employing incoherent scatter, magnetograms, and preferably an HF-CW doppler sounder would be able to resolve the origin and nature of these intriguing waves observed for the first time in f0F2 fluctuations.
BibTeX:
@article{Ganguly1982,
  author = {Ganguly, S. and Behnke, R. A.},
  title = {Short-period fluctuations in F region ionization observed at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1982},
  volume = {87},
  number = {A1},
  pages = {261-264},
  url = {http://dx.doi.org/10.1029/JA087iA01p00261},
  doi = {10.1029/JA087iA01p00261}
}
Gonzales CA, Behnke RA and Woodman RF (1982), "Doppler measurements with a digital ionosonde: Technique and comparison of results with incoherent scatter data", Radio Science. Vol. 17(5), pp. 1327-1333.
Abstract: A simple technique for measuring the amplitude and Doppler shift of vertically reflected HF echoes has been implemented for the Arecibo digital ionosonde. This technique can easily be adapted to other digital ionosondes controlled by small computers and/or microprocessors to provide the additional Doppler information. By using this technique, we have measured on-line the echo amplitude and the apparent vertical velocity of the reflecting layers. Furthermore, we have compared these data with simultaneous incoherent scatter measurements of vertical ionization drifts. The ionosonde and incoherent scatter results almost always agrree during the nighttime but do not agree during the daytime. We discuss these results.
BibTeX:
@article{Gonzales1982,
  author = {Gonzales, C. A. and Behnke, R. A. and Woodman, R. F.},
  title = {Doppler measurements with a digital ionosonde: Technique and comparison of results with incoherent scatter data},
  journal = {Radio Science},
  year = {1982},
  volume = {17},
  number = {5},
  pages = {1327-1333},
  url = {http://dx.doi.org/10.1029/RS017i005p01327},
  doi = {10.1029/RS017i005p01327}
}
Mahajan K, Pandey V and Jain V (1982), "Relationship between electron density and electron temperature as a function of solar activity ", Advances in Space Research . Vol. 2(10), pp. 247-249.
BibTeX:
@article{Mahajan1982,
  author = {K.K. Mahajan and V.K. Pandey and V.C. Jain},
  title = {Relationship between electron density and electron temperature as a function of solar activity },
  journal = {Advances in Space Research },
  year = {1982},
  volume = {2},
  number = {10},
  pages = {247-249},
  doi = {10.1016/0273-1177(82)90399-4}
}
Mathews JD, Breakall JK and Ganguly S (1982), "The measurement of diurnal variations of electron concentration in the 60-100 km ionosphere at Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 44, pp. 441-448.
BibTeX:
@article{Mathews1982,
  author = {Mathews, J D and Breakall, J K and Ganguly, S},
  title = {The measurement of diurnal variations of electron concentration in the 60-100 km ionosphere at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  pages = {441-448},
  doi = {10.1016/0021-9169(82)90050-2}
}
Sato T and Woodman RF (1982), "Fine Altitude Resolution Radar Observations of Upper-Tropospheric and Lower-Stratospheric Winds and Waves", Journal of the Atmospheric Sciences. Vol. 39(11), pp. 2539-2545.
Abstract: Preliminary results of wind velocity measurements made using the Arecibo 430 MHz radar are presented. These measurements were made in the altitude range between 10 and 30 km, with a time resolution of 1–2 min, and an improved altitude resolution of 150 m. A few interesting phenomena such as a quasi-stationary wavy structure and short period sinusoidal oscillations are discussed.
BibTeX:
@article{Sato1982,
  author = {Sato, T. and Woodman, R. F.},
  title = {Fine Altitude Resolution Radar Observations of Upper-Tropospheric and Lower-Stratospheric Winds and Waves},
  journal = {Journal of the Atmospheric Sciences},
  year = {1982},
  volume = {39},
  number = {11},
  pages = {2539-2545},
  url = {http://dx.doi.org/10.1175/1520-0469(1982)039<2539:FARROO>2.0.CO;2}
}
Sato T and Woodman RF (1982), "Fine Altitude Resolution Observations of Stratospheric Turbulent Layers by the Arecibo 430 MHz Radar", Journal of the Atmospheric Sciences. Vol. 39, pp. 2546-2552.
Abstract: Stratospheric turbulence is now observed by the Arecibo 430 MHz radar with an improved altitude resolution of 150 m. Turbulence is observed to occur in thin layers with a thickness usually less than the altitude resolution, and estimated to be about 50 m. A clear correlation is found between the power, wind shear and spectral width of the echoes. A simple method of estimating the energy dissipation rate and the eddy diffusivity is examined. Values of the order of 0.2 m2 s-1 are found for the eddy diffusivity coefficient in the lower stratosphere, showing the importance of turbulence on vertical transport.
BibTeX:
@article{Sato1982a,
  author = {Toru Sato and Ronald F. Woodman},
  title = {Fine Altitude Resolution Observations of Stratospheric Turbulent Layers by the Arecibo 430 MHz Radar},
  journal = {Journal of the Atmospheric Sciences},
  year = {1982},
  volume = {39},
  pages = {2546-2552},
  url = {http://dx.doi.org/10.1175/1520-0469(1982)039<2546:FAROOS>2.0.CO;2}
}
Sato T and Woodman RF (1982), "Spectral parameter estimation of CAT radar echoes in the presence of fading clutter", Radio Science. Vol. 17(4), pp. 817-826.
Abstract: The 430 MHz, 2 MW radar at the Arecibo Observatory is currently being used as a stratospheric-troposheric (ST) radar. One of the problems in the automatic analysis of the signals come from the very large amplitude of the ground clutter echoes. The problem is agravated by the fading of these signals, which makes it difficult to discriminate them from the desired stratospheric returns. A parameter estimation technique that parameterizes the first three-spectral moments corresponding to the desired stratospheric signals as well as a few Taylor series coefficients of the auto-correlation function of the clutter is presented. The three first moments can be obtained in this manner even in the presence of clutter 50 dB stronger. The technique automatically takes care of instrumental and processing biases. Spectrum aliasing presents no problem. A sequence of fine altitude and high temporal resolution wind profiles is presented, showing the potential of the instrumental and technique for the study of stratospheric dynamics.
BibTeX:
@article{Sato1982b,
  author = {Sato, Toru and Woodman, R. F.},
  title = {Spectral parameter estimation of CAT radar echoes in the presence of fading clutter},
  journal = {Radio Science},
  year = {1982},
  volume = {17},
  number = {4},
  pages = {817-826},
  url = {http://dx.doi.org/10.1029/RS017i004p00817},
  doi = {10.1029/RS017i004p00817}
}
Sulzer MP, Mathews JD and Tomko AA (1982), "A UHF cross-modulation D region heating experiment with aeronomic implications", Radio Science. Vol. 17(2), pp. 435-443.
Abstract: A unique wave interaction experiment employing the Arecibo 2.0-MW, 430-MHz radar as disturbing or heating transmitter has been performed. The purpose of this experiment was to evaluate UHF electron heating effects and to extend the wave interaction technique to higher than usual heights (˜100 km). The heater beam used was much smaller in angular extent than the probing or wanted beam, yielding an unfavorable geometric weighting factor and making the experiment very sensitive to reflection properties of the E region. Nonetheless, wave interaction was easily detected using a completely digital signal processing technique. Comparison of experimental wave interaction results with a numerical model of the process indicates that lower thermosphere electron cooling rates are possibly too small by a factor of 4. Power spectra of the 3.155 MHz wanted signal (reflected from E region) amplitude fluctuations for ‘quiet’ and ‘disturbed’ days are also given.
BibTeX:
@article{Sulzer1982,
  author = {Sulzer, M. P. and Mathews, J. D. and Tomko, A. A.},
  title = {A UHF cross-modulation D region heating experiment with aeronomic implications},
  journal = {Radio Science},
  year = {1982},
  volume = {17},
  number = {2},
  pages = {435-443},
  url = {http://dx.doi.org/10.1029/RS017i002p00435},
  doi = {10.1029/RS017i002p00435}
}
Zinn J, Sutherland C, Stone S, Duncan L and Behnke R (1982), "Ionospheric effects of rocket exhaust products-heao-c, skylab", Journal of Atmospheric and Terrestrial Physics. Vol. 44(12), pp. 1143-1171.
BibTeX:
@article{Zinn1982,
  author = {J Zinn and C.D Sutherland and S.N Stone and L.M Duncan and R Behnke},
  title = {Ionospheric effects of rocket exhaust products-heao-c, skylab},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1982},
  volume = {44},
  number = {12},
  pages = {1143-1171},
  doi = {10.1016/0021-9169(82)90025-3}
}
FUKAO S, MAEKAWA Y and KATO S (1981), "A Semidiurnal Wind Oscillation with Short Vertical Wavelength Observed in the Tropical Lower Stratosphere", Journal of geomagnetism and geoelectricity. Vol. 33(8), pp. 421-427.
Abstract: Radar measurement of the tropical lower stratosphere at Jicamarca (12°S) reaffirmed the existence of a semidiurnal wind oscillation similar to that detected foremost at Arecibo (18°N), which has a vertical wavelength as short as 10km and a horizontal wind amplitude of 0.2-1ms-1. It seems very important that the two measurements made in different hemispheres detect a similar type of semidiurnal oscillation, being significantly different from global tidal oscillations.
BibTeX:
@article{1981421,
  author = {Shoichiro FUKAO and Yasuyuki MAEKAWA and Susumu KATO},
  title = {A Semidiurnal Wind Oscillation with Short Vertical Wavelength Observed in the Tropical Lower Stratosphere},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1981},
  volume = {33},
  number = {8},
  pages = {421-427},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/33/8/33_8_421/_article},
  doi = {10.5636/jgg.33.421}
}
Basu S, Basu S, Ganguly S and Klobuchar JA (1981), "Generation of kilometer scale irregularities during the midnight collapse at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 86(A9), pp. 7607-7616.
Abstract: Coordinated observations of the incoherent scatter radar at Arecibo, Puerto Rico, and total electron content/scintillation measurements made by using the 137-MHz transmissions from the geostationary satellite SMS 1 from the nearby station of Ramey are studied to determine the background ionospheric conditions necessary for the generation of kilometer scale irregularities in the midlatitude ionosphere. It is found that the well-known midnight descent or collapse of the F region known to occur in this part of the world is sometimes associated with increases in the bottomside electron content, as well as large scintillation events (~10 dB). From a measurement of vector ion velocities and electron densities during such events, it is determined that the scintillations occur in a region of eastward and northward electric fields coupled with a northward directed density gradient caused by the northward propagation of the midnight collapse. The role of possible plasma instability mechanisms, specifically the E â B gradient drift instability and the Perkins instability, is discussed in the formation of the kilometer scale irregularities giving rise to VHF scintillations.
BibTeX:
@article{Basu1981,
  author = {Basu, Sunanda and Basu, Santimay and Ganguly, S. and Klobuchar, J. A.},
  title = {Generation of kilometer scale irregularities during the midnight collapse at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A9},
  pages = {7607-7616},
  url = {http://dx.doi.org/10.1029/JA086iA09p07607},
  doi = {10.1029/JA086iA09p07607}
}
Burnside RG, Meriwether JW and Walker JCG (1981), "Reply [to “Comment on ‘Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm’ by Roger G. Burnside, John W. Meriwether, and James C. G. Walker”]", Journal of Geophysical Research: Space Physics. Vol. 86(A6), pp. 4841-4841.
BibTeX:
@article{Burnside1981,
  author = {Burnside, Roger G. and Meriwether, John W. and Walker, James C. G.},
  title = {Reply [to “Comment on ‘Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm’ by Roger G. Burnside, John W. Meriwether, and James C. G. Walker”]},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A6},
  pages = {4841-4841},
  url = {http://dx.doi.org/10.1029/JA086iA06p04841},
  doi = {10.1029/JA086iA06p04841}
}
Burnside RG, Herrero FA, Meriwether JW and Walker JCG (1981), "Optical observations of thermospheric dynamics at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 86(A7), pp. 5532-5540.
Abstract: Observations of thermospheric neutral winds have been made at Arecibo, Puerto Rico, by using a Fabry-Perot interferometer to measure the Doppler shift of the nighttime O(¹D) 630-nm emission. We have developed a scheme of making observations at eight equally-spaced azimuth positions with a constant zenith angle. This technique allows us to determine the mean neutral wind velocities in the meridional and zonal directions, as well as any horizontal gradients in the wind field. It also provides a good means of simultaneously monitoring any spatial variations in neutral temperature and the intensity of the O(¹D) emission. In general, the highest equatorward wind velocity is observed at about 2100 LST. The meridional wind velocity usually lessens as midnight approaches and sometimes, but by no means always, reverses after midnight. The magnitude of the equatorward velocity is greater in summer than in winter months. For winter and spring months, the zonal wind blows eastward throughout the night, with the velocity tending to decrease in a fairly regular fashion from about 125 m s?1 at 2100 LST towards zero by 0400 LST. In summer the pattern is similar, but the eastward flow usually reverses earlier, and a westward velocity of some 50 m s?1 may be attained by 0400 LST. Significant horizontal wind gradients are often observed in the meridional direction, but not in the zonal direction. Near midnight especially, during both the equinox and summer months, the equatorward wind is often greater to the north of Arecibo than to the south. We interpret this as being an effect of the passage of the midnight equatorial pressure maximum to the south of the station. Measurements of neutral temperature with the interferometer do indeed show that, between 0100–0200 LST, the neutral temperature to the south of Arecibo is enhanced by some 40°K over that to the north.
BibTeX:
@article{Burnside1981b,
  author = {Burnside, R. G. and Herrero, F. A. and Meriwether, J. W. and Walker, J. C. G.},
  title = {Optical observations of thermospheric dynamics at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A7},
  pages = {5532-5540},
  url = {http://dx.doi.org/10.1029/JA086iA07p05532},
  doi = {10.1029/JA086iA07p05532}
}
Fejer BG, Farley DT, Gonzales CA, Woodman RF and Calderon C (1981), "F region east-west drifts at Jicamarca", Journal of Geophysical Research: Space Physics. Vol. 86(A1), pp. 215-218.
Abstract: F region east-west drifts have been measured at Jicamarca for almost 10 years, using incoherent scatter. The drifts are westward during the day and eastward at night. The daytime drift velocities are about 50 m/s and change very little with season or solar cycle. The evening reversal occurs at about 1600 local time throughout the solar cycle. The maximum nighttime eastward drifts are about 105 and 130 m/s during solar minimum and maximum, respectively. The daytime and nighttime drifts show very litle variation with magnetic activity. These Jicamarca incoherent scatter results (especially the reversal times) differ appreciably from results obtained using other techniques, but there appear to be fairly simple explanations for the apparent disagreements.
BibTeX:
@article{Fejer1981,
  author = {Fejer, B. G. and Farley, D. T. and Gonzales, C. A. and Woodman, R. F. and Calderon, C.},
  title = {F region east-west drifts at Jicamarca},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A1},
  pages = {215-218},
  url = {http://dx.doi.org/10.1029/JA086iA01p00215},
  doi = {10.1029/JA086iA01p00215}
}
Fukuyama K (1981), "Incoherent scatter radar observations of wavelike structures in the mesosphere over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 86(A11), pp. 9152-9158.
Abstract: The 430-MHz radar at Arecibo has been used to observe the ion component of the incoherent scatter spectrum in the mesosphere. Vertical profiles of the zonal winds deduced from the radar backscatter show excellent agreement with profiles obtained from meteorological rocket soundings from Antigua. Meridional winds and the spectrum parameters (width and relative power) observed on a summer day exhibit wavelike structures which move downward with time. The wavelike structures in the spectrum parameters, pronounded particularly in the D region ledge, are discussed somewhat qualitatively, in relation to transport processes of neutral and ionized particles by the atmospheric motions.
BibTeX:
@article{Fukuyama1981,
  author = {Fukuyama, K.},
  title = {Incoherent scatter radar observations of wavelike structures in the mesosphere over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A11},
  pages = {9152-9158},
  url = {http://dx.doi.org/10.1029/JA086iA11p09152},
  doi = {10.1029/JA086iA11p09152}
}
Harper R (1981), "Some results on mean tidal structure and day-to-day variability over Arecibo", Journal of Atmospheric and Terrestrial Physics . Vol. 43(3), pp. 255-262.
Abstract: A long series of monthly 36 h observations, plus a series of observations at the same local time each day over two months at Arecibo, have been analyzed for tidal structure and variability. Some of the results are as follows. (1) A diurnal tide with vertical structure similar to that of the S1,1 mode dominates the wind field up to heights of the order of 110 km over Arecibo. A semidiurnal oscillation dominates above that height. For non-winter conditions the semidiurnal oscillation in the 80–200 km region closely resembles the S2,2 mode, though there is the possibility of contributions from higher order modes in the 100–120 km region. (2) Larger semidiurnal amplitudes are observed in the lower thermosphere for winter conditions. The data appears roughly consistent with Bernard's (1979) hypothesis that S2,2, S2,4 and S2,5 modes are thermally excited, with the S2,4 and S2,5 modes out of phase in the meteor region in summer and in phase in winter. (3) The day-to-day variability of the tides is at least half the amplitude of the mean oscillations. The maximum wind variability was observed to occur in the 100–110 km region where the diurnal tide is strongly dissipated. (4) The day-to-day deviations in the wind and temperature oscillations from a long term mean at one local time tend to be wave-like structures which are generally correlated from day to day. The structures tend to move upwards, i.e., appear at a later local time, from day to day.
BibTeX:
@article{Harper1981,
  author = {R.M Harper},
  title = {Some results on mean tidal structure and day-to-day variability over Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1981},
  volume = {43},
  number = {3},
  pages = {255-262},
  url = {http://www.sciencedirect.com/science/article/pii/0021916981900477},
  doi = {10.1016/0021-9169(81)90047-7}
}
Herrero F and Jr JM (1981), "Equatorial night-time F-region events: a survey of 6300 A airglow intensity maps at Arecibo", Journal of Atmospheric and Terrestrial Physics . Vol. 43(8), pp. 859-866.
Abstract: 6300 A nightglow intensities have been mapped along an arc following the emission layer. The resulting time vs zenith angle airglow maps show significant structure which is classified into three main types: meridional intensity gradients (MIG), F-region southward propagating waves, and short wavelength (about 100 km) events. Interpretation of winter MIG data suggests that the equatorial midnight pressure bulge is in the northern hemisphere in winter and in the southern hemisphere in summer.
BibTeX:
@article{Herrero1981,
  author = {F.A Herrero and J.W Meriwether Jr},
  title = {Equatorial night-time F-region events: a survey of 6300 A airglow intensity maps at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1981},
  volume = {43},
  number = {8},
  pages = {859-866},
  url = {http://www.sciencedirect.com/science/article/pii/0021916981900647},
  doi = {10.1016/0021-9169(81)90064-7}
}
Mantas GP, Carlson HC and LaHoz CH (1981), "Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves", Journal of Geophysical Research: Space Physics. Vol. 86(A2), pp. 561-574.
BibTeX:
@article{Mantas1981,
  author = {Mantas, George P. and Carlson, Herbert C. and LaHoz, Caesar H.},
  title = {Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A2},
  pages = {561-574},
  doi = {10.1029/JA086iA02p00561}
}
Mathews JD (1981), "D-region research at Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 43, pp. 549-556.
BibTeX:
@article{Mathews1981,
  author = {Mathews, J D},
  title = {D-region research at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1981},
  volume = {43},
  pages = {549-556},
  doi = {10.1016/0021-9169(81)90117-3}
}
Mathews JD, Sulzer MP, Tepley CA, Bernard R, Fellous JL, Glass M, Massebeuf M, Ganguly S, Harper RM and Behnke RA (1981), "A comparison between Thomson scatter and meteor radar wind measurements in the 65-105 km altitude region at Arecibo", Planetary and Space Science. Vol. 29, pp. 341-348.
Abstract: The results of simultaneous meteor and Thomson scatter radar wind measurements in the 65–105 km altitude region are presented. The two radars are located in Puerto Rico where the 430-MHz Thomson scatter radar at Arecibo Observatory is employed along with the French (CNET) portable meteor radar which is at a 40-km distance. The two sets of wind measurements compare quite favorably during periods of coincident observation. The meteor radar yields continuous results while the Thomson scatter radar is usable only during daylight hours. The Thomson scatter results, on the other hand, extend down to 65 km altitude and are available with better height and time resolutions than the meteor radar results. The two measurement techniques are therefore complementary.
BibTeX:
@article{Mathews1981a,
  author = {Mathews, J D and Sulzer, M P and Tepley, C A and Bernard, R and Fellous, J L and Glass, M and Massebeuf, M and Ganguly, S and Harper, R M and Behnke, R A},
  title = {A comparison between Thomson scatter and meteor radar wind measurements in the 65-105 km altitude region at Arecibo},
  journal = {Planetary and Space Science},
  year = {1981},
  volume = {29},
  pages = {341-348},
  url = {http://dx.doi.org/10.1016/0032-0633(81)90022-2},
  doi = {10.1016/0032-0633(81)90022-2}
}
Munninghoff D and Bowhill S (1981), "Electron, H+ and O+ temperatures and densities from Arecibo incoherentscatter results ", Journal of Atmospheric and Terrestrial Physics . Vol. 43(4), pp. 269-275.
BibTeX:
@article{Munninghoff1981,
  author = {D.E Munninghoff and S.A Bowhill},
  title = {Electron, H+ and O+ temperatures and densities from Arecibo incoherentscatter results },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1981},
  volume = {43},
  number = {4},
  pages = {269-275},
  doi = {10.1016/0021-9169(81)90089-1}
}
Rottger J, Czechowsky P and Schmidt G (1981), "First low-power VHF radar observations of tropospheric, stratospheric and mesospheric winds and turbulence at the Arecibo Observatory", Journal of Atmospheric and Terrestrial Physics . Vol. 43(8), pp. 789-800.
Abstract: First VHF radar measurements with height resolution of 300 m and angular resolution of 1.7° were carried out in low latitudes at the Arecibo Observatory, Puerto Rico. A short outline is given of the experimental set-up which consisted of a 160W average power radar-transceiver and a self-contained digital radar control and data acquisition unit. The new VHF feed system of the Arecibo dish is described shortly. Reliable radar echoes were detected from the troposphere, lower stratosphere and from some heights in the mesosphere, indicating that the described VHF radar is capable of proper investigations of dynamical processes in the low latitude middle atmosphere. The angular dependence of aspect sensitive tropospheric and stratospheric turbulence structures was measured to be 1.5-2.5 dB degree-1. Echoes from the mesosphere indicate a patchy structure of turbulence. The analysis of the signal-to-noise ratio shows considerably high reflectivity in the upper troposphere, which can be caused by high-reaching tropical cumulus convection. Wind profiles measured with the VHF radar between 7.5 and 19.5 km with a height resolution of 300m are very similar to radiosonde wind profiles. Mesospheric VHF radar winds are roughly consistent in amplitude with tidal winds.
BibTeX:
@article{Rottger1981,
  author = {J. Rottger and P. Czechowsky and G. Schmidt},
  title = {First low-power VHF radar observations of tropospheric, stratospheric and mesospheric winds and turbulence at the Arecibo Observatory},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1981},
  volume = {43},
  number = {8},
  pages = {789-800},
  url = {http://www.sciencedirect.com/science/article/pii/0021916981900568},
  doi = {10.1016/0021-9169(81)90056-8}
}
Sahai Y, Bittencourt JA and Teixeira NR (1981), "Comment on “Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm” by Roger G. Burnside, John W. Meriwether, and James C. G. Walker", Journal of Geophysical Research: Space Physics. Vol. 86(A6), pp. 4839-4840.
BibTeX:
@article{Sahai1981,
  author = {Sahai, Y. and Bittencourt, J. A. and Teixeira, N. R.},
  title = {Comment on “Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm” by Roger G. Burnside, John W. Meriwether, and James C. G. Walker},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A6},
  pages = {4839-4840},
  url = {http://dx.doi.org/10.1029/JA086iA06p04839},
  doi = {10.1029/JA086iA06p04839}
}
Tepley CA, Mathews JD and Ganguly S (1981), "Incoherent scatter radar studies of mesospheric temperatures and collision frequencies at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 86(A13), pp. 11330-11334.
Abstract: The Arecibo 430 MHz incoherent scatter radar is used to measure the ion-neutral collision frequency and temperature of the atmosphere in the 70 to 100 km altitude range. These parameters are determined over altitude segments that are comparable to the scale height of the mesosphere. The spectra scattered from the mesosphere are collision dominated, that is, for the Arecibo radar frequency, ?i > 1 at all altitudes observed. Analysis of the widths of these spectra show that both the temperature and collision frequency values agree quite favorably with the Cira model atmosphere for the summer months.
BibTeX:
@article{Tepley1981,
  author = {Tepley, C. A. and Mathews, J. D. and Ganguly, S.},
  title = {Incoherent scatter radar studies of mesospheric temperatures and collision frequencies at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1981},
  volume = {86},
  number = {A13},
  pages = {11330-11334},
  url = {http://dx.doi.org/10.1029/JA086iA13p11330},
  doi = {10.1029/JA086iA13p11330}
}
Tinsley BA and Burnside RG (1981), "Precipitation of energetic neutral hydrogen atoms at Arecibo during a magnetic storm", Geophysical Research Letters. Vol. 8(1), pp. 87-90.
Abstract: The production of ionization at upper E region levels at Arecibo and other low latitude sites during magnetic storms had been previously found to be associated with a few rayleighs of N2+ 4278å emission, but it had not been possible to decide between energetic electrons, ions or neutrals as the primary particles involved.Observations of H Balmer ? emission during such an event now demonstrate that energetic hydrogen atoms or protons are involved. Of these, H atoms from charge exchange of ring current protons are the more plausible explanation. Smaller contributions to the ionization and N2+ emission by other species may be present, and larger contributions to energy deposition by precipitating oxygen are probably present.
BibTeX:
@article{Tinsley1981,
  author = {Tinsley, Brian A. and Burnside, Roger G.},
  title = {Precipitation of energetic neutral hydrogen atoms at Arecibo during a magnetic storm},
  journal = {Geophysical Research Letters},
  year = {1981},
  volume = {8},
  number = {1},
  pages = {87-90},
  url = {http://dx.doi.org/10.1029/GL008i001p00087},
  doi = {10.1029/GL008i001p00087}
}
Woodman RF (1981), "Correction to ‘High-altitude resolution stratospheric measurements with the Arecibo 430-MHz radar’", Radio Science. Vol. 16(6), pp. 1445-1445.
BibTeX:
@article{Woodman1981,
  author = {Woodman, R. F.},
  title = {Correction to ‘High-altitude resolution stratospheric measurements with the Arecibo 430-MHz radar’},
  journal = {Radio Science},
  year = {1981},
  volume = {16},
  number = {6},
  pages = {1445-1445},
  url = {http://dx.doi.org/10.1029/RS016i006p01445},
  doi = {10.1029/RS016i006p01445}
}
Bailey G (1980), "The topside ionosphere above Arecibo at equinox during sunspot maximum", Planetary and Space Science. Vol. 28(1), pp. 47-59. Elsevier Science.
Abstract: The coupled time-dependent O+ and H+ continuity and momentum equations and O+, H+ and electron heat balance equations are solved simultaneously within the L = 1.4 (Arecibo) magnetic flux tube between an altitude of 120 km and the equatorial plane. The results of the calculations are used in a study of the topside ionosphere above Arecibo at equinox during sunspot maximum. Magnetically quiet conditions are assumed.
The results of the calculations show that the L = 1.4 magnetic flux tube becomes saturated from an arbitrary state within 2–3 days. During the day the ion content of the magnetic flux tube consists mainly of O+ whereas O+ and H+ are both important during the night. There is an altitude region in the topside ionosphere during the day where ion-counterstreaming occurs with H+ flowing downward and O+ flowing upward. The conditions causing this ion-counterstreaming are discussed. There is a net chemical gain of H+ at the higher altitudes. This H+ diffuses both upwards and downwards whilst O+ diffuses upwards from its solar e.u.v. production source which is most important at the lower altitudes. During the night the calculated O+ and H+ temperatures are very nearly equal whereas during the day there are occasions when the H+ temperature exceeds the O+ temperature by about 300 K.
BibTeX:
@article{Bailey1980,
  author = {G.J. Bailey},
  title = {The topside ionosphere above Arecibo at equinox during sunspot maximum},
  journal = {Planetary and Space Science},
  publisher = {Elsevier Science},
  year = {1980},
  volume = {28},
  number = {1},
  pages = {47-59},
  url = {http://www.sciencedirect.com/science/article/pii/0032063380901038},
  doi = {10.1016/0032-0633(80)90103-8}
}
Burnside RG, Meriwether JW and Walker JC (1980), "Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm", Journal of Geophysical Research: Space Physics. Vol. 85(A2), pp. 767-773.
Abstract: During a severe geomagnetic storm the OI 7774 å triplet was observed to have an intensity of the order of 15R, reduced to the zenith. Theoretical calculations using electron density profiles obtained with the Arecibo incoherent scatter radar show that the measured intensities cannot be explained by either radiative or ion-ion recombination reactions. A possible correlation between the airglow enhancement and Dst has been found. Excitation by heavy neutral atoms or ions, for example, oxygen or O+, precipitating into the thermosphere is put forward as a possible explanation for enhanced 7774 å emission during this magnetic storm.
BibTeX:
@article{Burnside1980,
  author = {Burnside, Roger G. and Meriwether, John W. and Walker, James C.G.},
  title = {Airglow observations of the OI 7774-å multiplet at Arecibo during a magnetic storm},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A2},
  pages = {767-773},
  url = {http://dx.doi.org/10.1029/JA085iA02p00767},
  doi = {10.1029/JA085iA02p00767}
}
Butcher EC (1980), "On the location of the ionospheric current systems responsible for the lunar and solar magnetic variations", Geophysical Journal International. Vol. 63, pp. 775-782.
Abstract: From a study of the sunspot cycle influence on the lunar (L) and solar (S) daily geomagnetic variations, Malin, Cecere & Palumbo have suggested that the electric currents responsible for these variations do not flow in the E-region as has hitherto been accepted. Indeed they suggested that the L current may even flow in the F2 region. The consequences of such a suggestion are considered and it is shown that an L current in the F-region is highly unlikely from the dynamical point of view. The evidence for E-region currents is presented and it is suggested that the variation of E-region electron density used by Malin et al. to indicate conductivity changes in that region may not be a reliable indicator of such changes.
BibTeX:
@article{Butcher1980,
  author = {E. C. Butcher},
  title = {On the location of the ionospheric current systems responsible for the lunar and solar magnetic variations},
  journal = {Geophysical Journal International},
  year = {1980},
  volume = {63},
  pages = {775-782},
  url = {http://gji.oxfordjournals.org/content/63/3/775.abstract?sid=16e19546-04fb-4046-91fc-da713cd31cff},
  doi = {10.1111/j.1365-246X.1980.tb02651.x}
}
Cogger L, Walker J, Meriwether J and Burnside R (1980), "F region airglow: Are ground-based observations consistent with recent satellite results?", Journal of Geophysical Research: Space Physics. Vol. 85(A6), pp. 3013-3020.
Abstract: Because previous interpretations of ground-based airglow measurements have used photochemical rate coefficients quite different from those deduced from the Atmosphere Explorer series of measurements, the question arises of whether the AE rates are as successful at explaining ground-based data as they are at explaining satellite data. In this paper we use the AE photochemistry to interpret simultaneous observations made at the Arecibo Observatory of the O I (6300 å) and N I (5200 å) airglow surface brightness and electron density and temperature profiles measured by incoherent scatter radar. We find that theory and experiment are in agreement for the 5200-å emission. However, we are unable to obtain complete agreement for the 6300-å nightglow and suggest that the source of the discrepancy lies with one of the parameters used to calculate the production rate of O(¹D). The data show clear evidence of an asymmetrical behavior of the ionosphere between times when the F layer is descending and times when it is ascending. This asymmetry probably reflects the effects of transport on molecular ion densities in the bottom side of the F region. Our results support a low rate for the quenching reaction between N(²D) and O. Calculations indicate that measurements of airglow surface brightnesses are relatively insensitive to the abundance of atomic nitrogen in the atmosphere.
BibTeX:
@article{Cogger1980,
  author = {Cogger, L.L. and Walker, J.C.G. and Meriwether, J.W. and Burnside, R.G.},
  title = {F region airglow: Are ground-based observations consistent with recent satellite results?},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A6},
  pages = {3013-3020},
  url = {http://dx.doi.org/10.1029/JA085iA06p03013},
  doi = {10.1029/JA085iA06p03013}
}
Fukao S, Sato T, Yamasaki N, Harper RM and Kato S (1980), "Radar Measurement of Tidal Winds at Stratospheric Heights over Arecibo", Journal of the Atmospheric Sciences. Vol. 37, pp. 2540-2544.
Abstract: Wind oscillations of tidal periods that showed a marked downward phase progression were detected at the lower stratosphere using the Arecibo radar. The amplitudes of 1-5 m s-1 were inferred for both diurnal and semidiurnal components, much larger than the values predicted by the classical tidal theory. The vertical wavelengths inferred were also less than the theoretical values; 5 km for the diurnal component and 2–9 km for the semidiurnal component.
BibTeX:
@article{Fukao1980,
  author = {Shoichiro Fukao and Toru Sato and Norikazu Yamasaki and Robert M. Harper and Susumu Kato},
  title = {Radar Measurement of Tidal Winds at Stratospheric Heights over Arecibo},
  journal = {Journal of the Atmospheric Sciences},
  year = {1980},
  volume = {37},
  pages = {2540-2544},
  url = {http://dx.doi.org/10.1175/1520-0469(1980)037<2540:RMOTWA>2.0.CO;2}
}
Ganguly S (1980), "Incoherent scatter observations of mesospheric dynamics at Arecibo", Geophysical Research Letters. Vol. 7(5), pp. 369-372.
Abstract: Incoherent scatter spectral observations at Arecibo have been extended down to 59 km. For the first time vertical velocities in the mesosphere have been observed using this technique. The velocities unambiguously reveal a wavelike structure growing with height and varying in time. Above around 75 km, the vertical wavelength is around 16 km and the time period about 4 hours ± 20 minutes. Vertical velocities near 90 km were as large as 1 ms?1 and the apparent vertical energy flux was reasonably constant above 75 km. Below 75 km the energy flux was substantially lower, suggesting a mechanism where the gravity waves acquire significant energy from the diurnal tidal component trapped below the mesopause.The estimated adiabatic density and temperature changes near 90 km, estimated using simple idealized theories, were around 11%. The observed changes in spectral width were also found to be in harmony with estimated density and temperature changes to within 25%.
BibTeX:
@article{Ganguly1980,
  author = {Ganguly, Suman},
  title = {Incoherent scatter observations of mesospheric dynamics at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1980},
  volume = {7},
  number = {5},
  pages = {369-372},
  url = {http://dx.doi.org/10.1029/GL007i005p00369},
  doi = {10.1029/GL007i005p00369}
}
Ganguly S (1980), "Short-term variability in the HF-enhanced plasma line", Journal of Geophysical Research: Space Physics. Vol. 85(A4), pp. 1783-1786.
Abstract: Plasma lines enhanced by HF radio waves have been used as a tracer of electron density fluctuations in the ionosphere. Both the intensity and the altitude of these plasma lines have been measured with very short time and range resolution. The power spectrum of the range variations indicates a power law dependence with a spectral index of -2.0 over periods of a few minutes to about 8 s; corresponding amplitudes are greater than 500 m to ~70 m. Instability and turbulent mechanisms seem to be responsible for the dissipation of large-scale irregularities to form continuously smaller scale sizes. Furthermore, isolated peaks of about 2- to 6-s periods with amplitudes of about 15-90 m have been observed on several occasions. The possible source of these fluctuations could be sound waves ducted in the ionosphere.
BibTeX:
@article{Ganguly1980a,
  author = {Suman Ganguly},
  title = {Short-term variability in the HF-enhanced plasma line},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A4},
  pages = {1783-1786},
  url = {http://dx.doi.org/10.1029/JA085iA04p01783},
  doi = {10.1029/JA085iA04p01783}
}
Ganguly S, Walker J and Rishbeth H (1980), "The dynamic F2-layer over Arecibo", Journal of Atmospheric and Terrestrial Physics . Vol. 42(6), pp. 553 - 562.
Abstract: The idealized ‘servo’ model of the ionospheric F2-layer, developed by Rishbeth, ganguly and Walker (1978), is used to simulate the observed behaviour of the daytime F2-peak at Arecibo for sunspot minimum. Taking the east-west electric field to be given by the observed plasma drift velocity perpendicular to the magnetic field, the theoretical equations are integrated using a trial-and-error approach to match the observed values of field-parallel plasma velocity, and the height and electron density of the F2-peak. From the calculation is determined empirically the meridional pressure-gradient force associated with the meridional neutral-air wind. The local time variation during the day is found to be consistent with the semidiurnal variation given by the MSIS atmospheric model of Hedinet al. (1977a, b), though with a phase shift that varies with season; on some days in the fall the pressure-gradient force displays a strong equatorward ‘surge’ in the evening. The values of F2-layer loss and diffusion coefficients needed to match the data are broadly consistent with the MSIS model. The analysis thus validates the MSIS model by way of ionospheric parameters quite independent of the data from which MSIS was originally derived.
BibTeX:
@article{Ganguly1980b,
  author = {S Ganguly and J.C.G Walker and H Rishbeth},
  title = {The dynamic F2-layer over Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1980},
  volume = {42},
  number = {6},
  pages = {553 - 562},
  url = {http://www.sciencedirect.com/science/article/pii/0021916980900653},
  doi = {10.1016/0021-9169(80)90065-3}
}
Gonzales CA, Kelley MC, Carpenter DL, Miller TR and Wand RH (1980), "Simultaneous measurements of ionospheric and magnetospheric electric fields in the outer plasmasphere", Geophysical Research Letters. Vol. 7(7), pp. 517-520.
Abstract: The eastward component of the electric field was measured simultaneously at ionospheric heights and in the equatorial plane of the magnetosphere by using the incoherent scatter radar at Millstone Hill and whistler data from Siple, Antarctica, respectively. The locations of the two data sets correspond to approximately magnetically conjugate areas within the outer plasmaphere, and thus a unique opportunity arises for testing the electric field mapping hypothesis and for intercomparing the measurement techniques. The whistler results are averaged for L = 3.5-4.7, while the radar data correspond to L = 4.4. The measurements represent time averages over about 20 minutes. There is excellent correlation during most of the 12 hour period of simultaneous data on 10 July 1978. The period was one of moderate disturbance (Kp = 2-3). A 500 gamma substorm developed around 0830 UT (0330 LT). During this substorm, both of the electric field measurements showed a large westward perturbation, in agreement with previous observations. The meridional component of the electric field was also measured at Millstone Hill. Taken together, these data indicate an enhanced flow with components inward and towards dawn during the substorm. Except for a time near magnetic midnight the magnitude of the zonal field scales from the ionosphere to the equator in direct ratio with the spreading of magnetic field lines in the IGRF 1975 model. The whistler data clearly show that the measurements were obtained inside the plasmasphere. The middle latitude substorm perturbations appeared to be related to a reconfiguration of the magnetospheric current system.
BibTeX:
@article{Gonzales1980,
  author = {Gonzales, C. A. and Kelley, M. C. and Carpenter, D. L. and Miller, T. R. and Wand, R. H.},
  title = {Simultaneous measurements of ionospheric and magnetospheric electric fields in the outer plasmasphere},
  journal = {Geophysical Research Letters},
  year = {1980},
  volume = {7},
  number = {7},
  pages = {517-520},
  url = {http://dx.doi.org/10.1029/GL007i007p00517},
  doi = {10.1029/GL007i007p00517}
}
Herrero F and Meriwether J (1980), "6300-A airglow meridional intensity gradients", Journal of Geophysical Research: Space Physics. Vol. 85(A8), pp. 4191-4204.
Abstract: Airglow meridional intensity gradients (MIG) that moved from east to west with the antisolar meridian have been observed during times of considerable magnetic activity. The magnitude of the gradient is around 0.1 R/km or more. We believe the MIG phenomenon develops as a result of a velocity gradient that is produced by the meeting of opposing meridional neutral winds. The northern wind system arises from the auroral heating at high latitude that produces meridional winds penetrating to low latitudes in the summer hemisphere. The southern wind system is produced by the equatorial midnight pressure bulge that is formed by the thermal tides of the lower atmosphere combined with the in situ forcing by EUV radiation absorption in the daytime. In a magnetic storm the merging of the two wind systems produces a sharp front over a latitudinal width of several hundred kilometers. North of the front the ionosphere is elevated, and the airglow is weak. South of the front the ionosphere is depressed, and the airglow is enhanced with a surface brightness of the order of 100 R. The conceptual model that evolved from these observations accounts for the overall behavior of the MIG as well as the normal midnight collapse. A simple calculation shows that the MIG can be used to estimate the meridional velocity gradient as well as the magnitude of the winds in the midnight pressure bulge.
BibTeX:
@article{Herrero1980,
  author = {Herrero, F.A. and Meriwether, J.W.},
  title = {6300-A airglow meridional intensity gradients},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A8},
  pages = {4191-4204},
  url = {http://dx.doi.org/10.1029/JA085iA08p04191},
  doi = {10.1029/JA085iA08p04191}
}
Kersley L, Aarons J and Klobuchar J (1980), "Nighttime enhancements in total electron content near Arecibo and their association with VHF scintillations", Journal of Geophysical Research: Space Physics. Vol. 85(A8), pp. 4214-4222.
Abstract: From the analysis of 16 months of transionospheric propagation data taken near Arecibo it has been found that there are associations between nighttime enhancements and quasi-periodic fluctuations in total electron content and the occurrence of amplitude scintillations. A postmidnight peak is found in the occurrence of electron content increases, maximum wave activity, and largest scintillation index, with some evidence to suggest a second premidnight peak in winter and reduced probability of the features being found at equinox. An analysis of the larger-scale variations of the total content data for three stations has shown that the postsunset minimum in electron content propagates at high speed toward the northeast, while the premidnight minimum advances toward the south with the main postmidnight maximum having a northward component of motion. The results are discussed in terms of the known dynamical features of the ionosphere at Arecibo and in particular the effects of the neutral wind on the bottomside ionosphere. It appears that conditions conducive to the production of nighttime enhancements in total electron content may also allow the penetration of medium scale gravity waves through the lower thermosphere with an unstable breakdown process giving rise to the development of scintillation-producing irregularities.
BibTeX:
@article{Kersley1980,
  author = {Kersley, L. and Aarons, J. and Klobuchar, J.A.},
  title = {Nighttime enhancements in total electron content near Arecibo and their association with VHF scintillations},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A8},
  pages = {4214-4222},
  url = {http://dx.doi.org/10.1029/JA085iA08p04214},
  doi = {10.1029/JA085iA08p04214}
}
Meriwether JW and Walker JC (1980), "First negative band system of nitrogen in the night sky over Arecibo during geomagnetic storms", Journal of Geophysical Research: Space Physics. Vol. 85(A3), pp. 1279-1284.
Abstract: Improvements in the airglow instrumentation at the Arecibo Observatory have permitted measurements of the brightness of the airglow emission from N2+ ions at 4278-å with sensitivity and time resolution much greater than those achieved when we first detected this emission in 1976. We report here the results of observations of this emission during magnetic storms in April and May of 1978. During this time surface brightnesses as high as 0.8 R were measured. The new measurements reveal fluctuations in brightness of the order of 20 per cent in times of about 30 minutes, which we tentatively attribute to fluctuations in the energetic particle flux that excites the emission. We also found a strong correlation between brightness and geomagnetic activity that was not apparent in our earlier, less sensitive measurements. The surface brightness at 4278-å increases at a rate of 0.4 to 0.5 R per 100 Y with increasing depression of Dst. Attempts to measure the rotational temperature of the emission were thwarted by contamination from molecular oxygen Herzberg bands, which we find to be significant at the very low levels of nitrogen emission which appear in the night sky at our latitude (18° north geographic, 30° geomagnetic).
BibTeX:
@article{Meriwether1980,
  author = {Meriwether, John W. and Walker, James C.G.},
  title = {First negative band system of nitrogen in the night sky over Arecibo during geomagnetic storms},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1980},
  volume = {85},
  number = {A3},
  pages = {1279-1284},
  url = {http://dx.doi.org/10.1029/JA085iA03p01279},
  doi = {10.1029/JA085iA03p01279}
}
Meriwether JW, Atreya SK, Donahue TM and Burnside RG (1980), "Measurements of the spectral profile of Balmer alpha emission from the hydrogen geocorona", Geophysical Research Letters. Vol. 7(11), pp. 967-970.
Abstract: Instrumental improvements responsible for a factor of 25 increase in the sensitivity of the Fabry-Perot interferometer enable us to observe for the first time the short wavelength depletion of the Balmer alpha spectral profile due to hydrogen escape. These results are shown to be consistent with the implications of OGO-5 observations by Bertaux.
BibTeX:
@article{Meriwether1980a,
  author = {Meriwether, J. W. and Atreya, S. K. and Donahue, T. M. and Burnside, R. G.},
  title = {Measurements of the spectral profile of Balmer alpha emission from the hydrogen geocorona},
  journal = {Geophysical Research Letters},
  year = {1980},
  volume = {7},
  number = {11},
  pages = {967-970},
  url = {http://dx.doi.org/10.1029/GL007i011p00967},
  doi = {10.1029/GL007i011p00967}
}
Walker JCG (1980), "Correlation of Wind and Electric Field in the Nocturnal F-Region", Geophysical Journal International. Vol. 60, pp. 85-94.
Abstract: The incoherent scatter radar at the Arecibo Observatory measures the ion drift velocity vector in the E- and F-regions of the ionosphere. This vector can be resolved into components parallel and perpendicular to the geomagnetic field. Nocturnal F-region data reveal a particularly marked negative correlation between the parallel component, which represents the combined effects of diffusion and a meridional wind, and the perpendicular component, which is caused by a zonal electric field. Various explanations of this correlation have been offered. One is that ion drag causes the F-region wind to respond to changes in the ion drift velocity. This explanation is not adequate, however, because nocturnal ion densities are too low for ion drag to affect the wind on the observed time scales of an hour or less. Another mechanism suggests that F-region winds lead to the generation of F-region polarization electrostatic fields, causing the perpendicular drift to respond to changes in the wind. Analysis of the data suggests that this mechanism does not account for the most striking examples of the correlation (those with short period), although it may operate weakly. The mechanism that appears to be most successful in accounting for the phenomenon attributes changes in the parallel component of the ion drift velocity to changes in the diffusion velocity resulting from changes in the F-layer height which result, in turn, from changes in the zonal electric field. Why the electrostatic field in the nocturnal ionosphere (and thus the perpendicular component of the ion drift velocity) should fluctuate as widely as the Arecibo data reveal is not known.
BibTeX:
@article{Walker1980,
  author = {Walker, J C G},
  title = {Correlation of Wind and Electric Field in the Nocturnal F-Region},
  journal = {Geophysical Journal International},
  year = {1980},
  volume = {60},
  pages = {85-94},
  doi = {10.1111/j.1365-246X.1980.tb02583.x}
}
Woodman RF (1980), "High-altitude-resolution stratospheric measurements with the Arecibo 2380-MHz radar", Radio Science. Vol. 15(2), pp. 423-430.
Abstract: The 2380-MHz planetary radar of the Arecibo Observatory and the 30-m interferometer antenna at Higuialles, Puerto Rico, have been instrumented as a bistatic radar for stratospheric turbulence research studies. The average power of the transmitter is 400 kW, and it uses the 300-m Arecibo spherical reflector. A vertical resolution of 30 m has been achieved by means of a novel continuous pseudorandom phase coding scheme. Preliminary results obtained with the system are presented. The thickness and internal structure of turbulent stratospheric layers have been resolved for the first time. The potential of the instrument in assessing the role of turbulence in the vertical transport of tracers, contaminants, and momentum is discussed.
BibTeX:
@article{Woodman1980,
  author = {Woodman, R. F.},
  title = {High-altitude-resolution stratospheric measurements with the Arecibo 2380-MHz radar},
  journal = {Radio Science},
  year = {1980},
  volume = {15},
  number = {2},
  pages = {423-430},
  url = {http://dx.doi.org/10.1029/RS015i002p00423},
  doi = {10.1029/RS015i002p00423}
}
Woodman RF (1980), "High-altitude resolution stratospheric measurements with the Arecibo 430-MHz radar", Radio Science. Vol. 15(2), pp. 417-422.
Abstract: The potential of the Arecibo 430-MHz radar for the study of stratospheric dynamics and turbulence has been recently established. In the past the instrumented resolution of the system has been larger than 300–600 m. The present paper describes instrumental modifications which have enabled us to obtain a resolution of 150 m, the maximum allowed by the transmitter bandwidth. Such a gain in resolution is very important for stratospheric studies, since it is expected that turbulence occurs at these altitudes in layers with thickness between a few tens to a few hundred meters. Furthermore, a complementary coded pulse scheme has been used for the first time. Such a code has the advantage of generating no pulse side lobes, an important property for defining the quiet regions existing in between turbulent layers. Decoding is performed digitally. The high data processing rate is taken care of by the use of a preprocessor. Power spectra of the signals corresponding to 256 altitudes are evaluated on line by means of an array processor peripheral connected to the processing computer. Useful echoes have been obtained from 10 km to about 30 km. The existence of layers of turbulence has been demonstrated, and their separation has been determined, but the thickness of some of them has still not been fully resolved. The separation of the layers varies as a function of altitude, changing from a few hundred meters at lower stratospheric heights to a few kilometers at 25- to 30-km altitudes. The results obtained show the importance of high resolution when using radars to obtain wind information from the Doppler shift of turbulence echoes.
BibTeX:
@article{Woodman1980a,
  author = {Woodman, R. F.},
  title = {High-altitude resolution stratospheric measurements with the Arecibo 430-MHz radar},
  journal = {Radio Science},
  year = {1980},
  volume = {15},
  number = {2},
  pages = {417-422},
  url = {http://dx.doi.org/10.1029/RS015i002p00417},
  doi = {10.1029/RS015i002p00417}
}
BLANC M (1979), "Electrodynamics of the Ionosphere from Incoherent Scatter: A Review", Journal of geomagnetism and geoelectricity. Vol. 31(3), pp. 137-164.
Abstract: The incoherent scatter technique has played an important role since 1970 in the study of the electrodynamics of the ionosphere, thanks to its ability to measure the altitude profile of the ionospheric currents and to give access simultaneously to all electrodynamic parameters of the ionosphere: electric fields, neutral winds, conductivities, and electric current densities. The various calculation schemes involved in the derivation of this set of parameters are presented. The main results obtained up to now in three different latitude regions, from the auroral electrojets to the equatorial electrojet, are reviewed. The most promising developments of these studies in the near future are tentatively indicated. They appear to be of prime importance for progress toward a satisfactory description of electric current flows in the ionosphere-thermosphere system.
BibTeX:
@article{1979137,
  author = {Michel BLANC},
  title = {Electrodynamics of the Ionosphere from Incoherent Scatter: A Review},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1979},
  volume = {31},
  number = {3},
  pages = {137-164},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/31/3/31_3_137/_article},
  doi = {10.5636/jgg.31.137}
}
FORBES JM and GARRETT HB (1979), "Solar Tidal Wind Structures and the E-Region Dynamo", Journal of geomagnetism and geoelectricity. Vol. 31(3), pp. 173-182.
Abstract: Recent theoretical models predict complicated tidal structures in the lower thermosphere which deviate from the classical Hough mode structures commonly used in E-region dynamo calculations. The present paper investigates the electrodynamic effects of such a theoretical wind field, and examines its consistency with measured magnetic effects on the ground. The model of tidal structure is constructed by synthesizing diurnal and semidiurnal contributions excited in-situ and propagating upwards from the mesosphere and below. The individual tidal structures, which are inseparable in their latitude and height dependence, are each determined by solving the linearized tidal equations for a spherical, rotating, viscous atmosphere with anisotropic ion drag. The amplitudes and phases of the individual tidal components are calibrated with incoherent scatter and satellite measurements. The dynamo computations are generally in good agreement in amplitude and phase with the diurnal and semidiurnal harmonics of the observed ground variations at minimum and maximum levels of solar activity. There are, however, real discrepancies on the order of 20% in amplitude and 1 to 2hr in phase which require explanation. In interpreting our theoretical simulations, we attempt to point out the structural features of the E-region tidal winds and conductivities which are most critical to establishing such a consistency between theory and experiment, and to evaluate the status of dynamo theory with particular regard to the structure and variability of the solar tidal winds.
BibTeX:
@article{1979173,
  author = {Jeffrey M. FORBES and Henry B. GARRETT},
  title = {Solar Tidal Wind Structures and the E-Region Dynamo},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1979},
  volume = {31},
  number = {3},
  pages = {173-182},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/31/3/31_3_173/_article},
  doi = {10.5636/jgg.31.173}
}
RICHMOND AD (1979), "Ionospheric Wind Dynamo Theory: A Review", Journal of geomagnetism and geoelectricity. Vol. 31(3), pp. 287-310.
Abstract: The current state of ionospheric wind dynamo theory is reviewed. Observational and theoretical advances in recent years have permitted more accurate models of the dynamo mechanism to be presented than previously, which have lent further credence to the validity of dynamo theory as the main explanation for quiet-day ionospheric electric fields and currents at middle and low latitudes. The diurnal component of the wind in the upper E region and lower F region appears to be primarily responsible for average quiet-day currents, although other wind components give significant contributions. Observationally, there is a need for better spatial and temporal coverage of wind and electric field data. Theoretically, there is a need for further consideration of the mutual dynamic coupling among winds, conductivities, electric fields, and electric currents, and for better modeling of nighttime conditions.
BibTeX:
@article{1979287,
  author = {A. D. RICHMOND},
  title = {Ionospheric Wind Dynamo Theory: A Review},
  journal = {Journal of geomagnetism and geoelectricity},
  year = {1979},
  volume = {31},
  number = {3},
  pages = {287-310},
  url = {https://www.jstage.jst.go.jp/article/jgg1949/31/3/31_3_287/_article},
  doi = {10.5636/jgg.31.287}
}
Behnke R (1979), "F layer height bands in the nocturnal ionosphere over Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A3), pp. 974-978.
Abstract: A study of the nocturnal F layer over Arecibo, Puerto Rico, reveals that substantial spatial variations in the height of the layer are frequently present. The variations are deduced from electron density profiles measured by the incoherent radar in which the radar beam is offset 17° in zenith and rotated continuously in azimuth. This scanning procedure shows that the ionosphere above Arecibo often has well-defined bands where the F region as a whole is alternately high and low. The transition between adjoining regions is very sharp. For example, electron density profiles taken at points only a few degrees apart in azimuth, which corresponds to a spatial separation of less than 10 km, can show variations in hmax of up to 70 km. It is suggested that these bands are manifestations of the so-called ‘Perkins’ instability.
BibTeX:
@article{Behnke1979,
  author = {Behnke, R.},
  title = {F layer height bands in the nocturnal ionosphere over Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A3},
  pages = {974-978},
  url = {http://dx.doi.org/10.1029/JA084iA03p00974},
  doi = {10.1029/JA084iA03p00974}
}
Bhonsle R, Sawant H and Degaonkar S (1979), "Exploration of the solar corona by high resolution solar decametric observations", Space Science Reviews. Vol. 24(3), pp. 259-346.
BibTeX:
@article{Bhonsle1979,
  author = {Bhonsle, R.V. and Sawant, H.S. and Degaonkar, S.S.},
  title = {Exploration of the solar corona by high resolution solar decametric observations},
  journal = {Space Science Reviews},
  year = {1979},
  volume = {24},
  number = {3},
  pages = {259-346},
  doi = {10.1007/BF00212422}
}
Farley DT, Swartz WE, La Hoz C and Balsley BB (1979), "Tropical winds measured by the Arecibo radar", Journal of Applied Meteorology. Vol. 18, pp. 227-230.
Abstract: Preliminary measurements of tropospheric and stratospheric parameters using the large 430 MHz radar at Arecibo, Puerto Rico, show excellent agreement between a wind profile deduced from the radar back-scatter and a profile obtained simultaneously from a rawinsonde ascent from San Juan. The measured variations of scattered power with altitude agree quite well with predictions of atmospheric turbulence theory.
BibTeX:
@article{Farley1979,
  author = {Farley, D T and Swartz, W E and La Hoz, C and Balsley, B B},
  title = {Tropical winds measured by the Arecibo radar},
  journal = {Journal of Applied Meteorology},
  year = {1979},
  volume = {18},
  pages = {227-230},
  url = {http://dx.doi.org/10.1175/1520-0450(1979)018<0227:TWMBTA>2.0.CO;2}
}
Fejer B, Farley D, Woodman R and Calderon C (1979), "Dependence of equatorial F region vertical drifts on season and solar cycle", Journal of Geophysical Research: Space Physics. Vol. 84(A10), pp. 5792-5796.
Abstract: Vertical drift measurements have been made at Jicamarca for more than half a solar cycle. The data from periods of high and low activity are appreciably different. Daytime drift velocities during sunspot minimum are usually larger than during the maximum, while the opposite is true for nighttime periods. The evening reversal occurs earlier during sunspot minimum than during the maximum, but the morning reversal is not altered. The period of eastward electric field (upward drift) is thus shortest during sunspot minimum and local winter. By integrating the drift velocity data with respect to time, one can obtain a measure of the total potential drop between reversal points (near the terminators). This drop is largest at solar maximum. There is also a pronounced seasonal variation, with a minimum in mid-December during both solar minimum and maximum. The general features of the data cannot be explained solely on the basis of tidal winds driving an E region dynamo; polarization fields related to the F region dynamo are of major importance, particularly in helping to explain the enhancement of the daytime upward drift which often occurs shortly before the drift reverses to downward in the evening. In order to account quantitatively for the observed variations, however, numerical models considerably more sophisticated than those presently available are needed.
BibTeX:
@article{Fejer1979,
  author = {Fejer, B.G. and Farley, D.T. and Woodman, R.F. and Calderon, C.},
  title = {Dependence of equatorial F region vertical drifts on season and solar cycle},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A10},
  pages = {5792-5796},
  url = {http://dx.doi.org/10.1029/JA084iA10p05792},
  doi = {10.1029/JA084iA10p05792}
}
Fejer B, Gonzales C, Farley D, Kelley M and Woodman R (1979), "Equatorial electric fields during magnetically disturbed conditions 1. The effect of the interplanetary magnetic field", Journal of Geophysical Research: Space Physics. Vol. 84(A10), pp. 5797-5802.
Abstract: Radar measurements of E and F region drift velocities have been used to look for correlations between changes in equatorial electric fields and the interplanetary magnetic field (IMF). The east-west component of the IMF appears to be unimportant, but the north-south component has some effect; rapid reversals from south to north are sometimes correlated with reversals of the equatorial east-west electric field during both daytime and nighttime. This is not always true, however, the IMF may reverse without any apparent effect at the equator. Furthermore, large equatorial field perturbations are sometimes observed when the IMF Bz is large and southward but not varying drastically. In this latter case the equatorial perturbations start nearly simultaneously with the onset of auroral substorms, while in the previous case they usually correlate with the onset of the substorm recovery phase. These observations indicate that the IMF does not affect the equatorial electric fields directly. Rather, it is changes in the magnetospheric electric fields and the auroral zone electric field and conductivity distribution (which may or may not be triggered by IMF changes) which alter the worldwide ionospheric current flow and electric field pattern, of which the equatorial observations are an indication.
BibTeX:
@article{Fejer1979a,
  author = {Fejer, B.G. and Gonzales, C.A. and Farley, D.T. and Kelley, M.C. and Woodman, R.F.},
  title = {Equatorial electric fields during magnetically disturbed conditions 1. The effect of the interplanetary magnetic field},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A10},
  pages = {5797-5802},
  url = {http://dx.doi.org/10.1029/JA084iA10p05797},
  doi = {10.1029/JA084iA10p05797}
}
Fukao S, Sato T, Kimura I and Harper RM (1979), "Seasonal mean structure of the night-time F2 region over Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 41, pp. {1,205-1,221}.
BibTeX:
@article{Fukao1979,
  author = {Fukao, S. and Sato, T. and Kimura, I. and Harper, R. ~M.},
  title = {Seasonal mean structure of the night-time F2 region over Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1979},
  volume = {41},
  pages = {1,205-1,221},
  doi = {10.1016/0021-9169(79)90024-2}
}
Fukao S, Sato T, Kato S, Harper R, Woodman R and Gordon W (1979), "Mesospheric winds and waves over Jicamarca on May 23–24, 1974", Journal of Geophysical Research: Space Physics. Vol. 84(A8), pp. 4379-4386.
Abstract: The VHF radar at Jicamarca (12.0°S, 76.9°W) was used to probe the mesosphere for 24 hours on May 23–24, 1974. The inferred zonal wind shows a strong eastward prevailing component below 75 km for these winter conditions, as would be expected from the annual and semiannual oscillations. The zonal winds are in good agreement in their region of overlap with rocket observations made at Ascension Island (8.0°S, 14.4°W) for the same period. This is the first direct confirmation that Jicamarca VHF observations are measuring mesospheric winds. Substantial wind oscillations are present, but the lack of nighttime echoes precludes a decomposition into tidal components. The dominant periodicity in the short-period oscillations changes with altitude, with the short-period cutoff decreasing from around 10 min at 70 km to 4 min at 80 km. This suggests both a local energy source for the oscillations and the importance of the background temperature structure in determining the wave characteristics. The variation of echo power with height in the two antennas that were used shows that 2–10 times more power was received on the average in the nearly vertical antenna than in the antenna offset from the vertical by 3.45° at heights below 75 km, suggesting the possibility that a ‘partial reflection’ mechanism is important in the 55- to 75-km region at a 50-MHz operating frequency. The powers in the two antennas become nearly equal above 75 km, with the possibility that slightly more power is received in the off-vertical antenna. The continuous scattered power becomes very small above 80 km; however, meteor echoes are frequently observed. Equatorial electrojet echoes dominate the echo returns above 85 km.
BibTeX:
@article{Fukao1979a,
  author = {Fukao, S. and Sato, T. and Kato, S. and Harper, R.M. and Woodman, R.F. and Gordon, W.E.},
  title = {Mesospheric winds and waves over Jicamarca on May 23–24, 1974},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A8},
  pages = {4379-4386},
  url = {http://dx.doi.org/10.1029/JA084iA08p04379},
  doi = {10.1029/JA084iA08p04379}
}
Ganguly S, Mathews JD and Tepley CA (1979), "Thomson scatter radar detection of D-region negative ions at Arecibo", Geophysical Research Letters. Vol. 6(2), pp. 89-92.
Abstract: The Arecibo 430 MHz radar has been used to measure D region Thomson scatter power spectra which display bandwidth and power variations with altitude and solar zenith angle which are consistent with the presence of negative ions. The negative ion-to-electron number density ratio (??), electron density, and electron-to-ion temperature ratio (Te/Ti) have been derived from the spectral data and presented for noontime and sunset conditions. The ?? = 1 level is found to occur near 70 km at noon and near 80 km at sunset. Values of Te/Ti in the range 1.0 to 1.5, due to probing pulse heating, were observed.
BibTeX:
@article{Ganguly1979,
  author = {Ganguly, S. and Mathews, J. D. and Tepley, C. A.},
  title = {Thomson scatter radar detection of D-region negative ions at Arecibo},
  journal = {Geophysical Research Letters},
  year = {1979},
  volume = {6},
  number = {2},
  pages = {89-92},
  url = {http://dx.doi.org/10.1029/GL006i002p00089},
  doi = {10.1029/GL006i002p00089}
}
Gonzales C, Kelley M, Fejer B, Vickrey J and Woodman R (1979), "Equatorial electric fields during magnetically disturbed conditions 2. Implications of simultaneous auroral and equatorial measurements", Journal of Geophysical Research: Space Physics. Vol. 84(A10), pp. 5803-5812.
Abstract: Simultaneous auroral and equatorial electric field data are used along with magnetic field data to study anomalous electric field patterns during disturbed times. During some substorms, accompanied by ring current activity, the worldwide equatorial zonal electric field component reverses from the normal pattern. This is interpreted as a partial closure of high latitude field aligned currents in the dayside, low latitude ionosphere. These currents flow westward across the dayside. In several cases the zonal equatorial electric field component was nearly identical in form to the zonal auroral component, indicating the close electrical coupling between these regions. Less certain, but equally intriguing, is the evidence presented for a close relationship between the zonal equatorial electric field and the time derivative of the ring current induced magnetic field. Another class of events seems related to rapid changes of magnetospheric convection and a temporary imbalance between the field external to the plasmasphere and the shielding charges in the Alfven layer. Examples of both rapid increases and decreases are presented. The latter seems often to be related to a northward turning of the interplanetary magnetic field.
BibTeX:
@article{Gonzales1979,
  author = {Gonzales, C.A. and Kelley, M.C. and Fejer, B.G. and Vickrey, J.F. and Woodman, R.F.},
  title = {Equatorial electric fields during magnetically disturbed conditions 2. Implications of simultaneous auroral and equatorial measurements},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A10},
  pages = {5803-5812},
  url = {http://dx.doi.org/10.1029/JA084iA10p05803},
  doi = {10.1029/JA084iA10p05803}
}
Kelley MC, Fejer BG and Gonzales CA (1979), "An explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field", Geophysical Research Letters. Vol. 6(4), pp. 301-304.
Abstract: Anomalous reversals of the zonal equatorial electric field component have sometimes been observed when the interplanetary magnetic field turns northward from a steady southerly direction. We suggest that this reversal is associated with a sudden change in the convection electric field in the magnetosphere and present measurements to support this explanation. Although slower variations in the convection field are shielded from the low latitude ionosphere by polarization charges at the inner edge of the ring current, these charges may require an hour or more to vary. A sudden decrease in the cross-tail electric field will thus be accompanied by a dusk-dawn perturbation electric field across the inner magnetosphere.
BibTeX:
@article{Kelley1979,
  author = {Kelley, M. C. and Fejer, B. G. and Gonzales, C. A.},
  title = {An explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field},
  journal = {Geophysical Research Letters},
  year = {1979},
  volume = {6},
  number = {4},
  pages = {301-304},
  url = {http://dx.doi.org/10.1029/GL006i004p00301},
  doi = {10.1029/GL006i004p00301}
}
Levine JS, Hays PB and Walker JC (1979), "The evolution and variability of atmospheric ozone over geological time", Icarus . Vol. 39(2), pp. 295 - 309.
Abstract: The rise of atmospheric O3 as a function of the evolution of O2 has been investigated using a one-dimensional steady-state photochemical model based on the chemistry and photochemistry of Ox(O3, O, O(1D)), N2O, NOx(NO, NO2, HNO3), H2O, and HOx(H, OH, HO2, H2O2) including the effect of vertical eddy transport on the species distribution. The total O3 column density was found to maximize for an O2 level of 10-1 present atmospheric level (PAL) and exceeded the present total O3 column by about 40%. For that level of O2, surface and tropospheric O3 densities exceeded those of the present atmosphere by about an order of magnitude. Surface and tropospheric OH densities of the paleoatmosphere exceeded those of the present atmosphere by orders of magnitude. We also found that in the O2-deficient paleoatmosphere, N2O (even at present atmospheric levels) produces much less NOx than it does in the present atmosphere.
BibTeX:
@article{Levine1979295,
  author = {Joel S. Levine and Paul B. Hays and James C.G. Walker},
  title = {The evolution and variability of atmospheric ozone over geological time},
  journal = {Icarus },
  year = {1979},
  volume = {39},
  number = {2},
  pages = {295 - 309},
  url = {http://www.sciencedirect.com/science/article/pii/0019103579901726},
  doi = {10.1016/0019-1035(79)90172-6}
}
Mathews J and Bekeny F (1979), "Upper atmosphere tides and the vertical motion of ionospheric sporadic layers at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A6), pp. 2743-2750.
Abstract: The vertical motion of ionospheric sporadic layers in the 80- to 140-km altitude region is examined by using a numerical solution for ion trajectories in a wind system composed of diurnal and semidiurnal tides similar to those observed at Arecibo. The confluence of the two tides in the 100- to 110-km altitude region is shown to produce a variety of layer motion possibilities including ‘quasi-stagnation’ of the layer as well as rapid upward or downward motions. Experimental layer trajectories are presented which confirm the basic theoretical results and which indicate the continuous opportunity for layers to form in the tidal wind system. The availability of metallic ions for layer formation is discussed as is the observed presence of layers below 90-km altitude.
BibTeX:
@article{Mathews1979,
  author = {Mathews, J.D. and Bekeny, F.S.},
  title = {Upper atmosphere tides and the vertical motion of ionospheric sporadic layers at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A6},
  pages = {2743-2750},
  url = {10.1029/JA084iA06p02743},
  doi = {10.1029/JA084iA06p02743}
}
Mayr HG, Harris I, Spencer NW, Hedin AE, Wharton LE, Porter HS, Walker JCG and Carlson HC (1979), "Tides and the midnight temperature anomaly in the thermosphere", Geophysical Research Letters. Vol. 6(6), pp. 447-450.
Abstract: Spectral analysis of the midnight temperature anomaly observed on AE-E indicates that the phenomenon can be adequately represented with wave numbers 1
BibTeX:
@article{Mayr1979,
  author = {Mayr, H. G. and Harris, I. and Spencer, N. W. and Hedin, A. E. and Wharton, L. E. and Porter, H. S. and Walker, J. C. G. and Carlson, H. C.},
  title = {Tides and the midnight temperature anomaly in the thermosphere},
  journal = {Geophysical Research Letters},
  year = {1979},
  volume = {6},
  number = {6},
  pages = {447-450},
  url = {http://dx.doi.org/10.1029/GL006i006p00447},
  doi = {10.1029/GL006i006p00447}
}
Meriwether JW (1979), "Measurement of weak airglow emissions with a programmable scanning spectrometer", Planetary and Space Science . Vol. 27(10), pp. 1221-1232.
Abstract: We demonstrate how the radiance response of a wavelength scanning instrument may be improved with a programmable scanning system. A minicomputer with a high level language offers a versatile software package that can be readily modified for any specific problem. We illustrate the technique with the application of the one meter Ebert Fastie spectrophotometer at the Arecibo Observatory's airglow facility to the measurements of the peak spectral emissions of the 5200 å doublet of N(2D) in the nightglow and the 7320 å doublet of O+(2P) in twilight. Typical measurement errors were ±0.2 R and ±0.5 R, respectively. We have also applied this method to measurements of the OH rotational temperature from the ratio of the P1(2) and the P1(5) rotational lines in the Meinel 8-3 band and obtained a precision of ±3 K within a time period of 6 min. The required modifications to the wavelength drive were not extensive, the costs were not high, and the technique may be applied to any wavelength scanning instrument in operation today.
BibTeX:
@article{Meriwether1979,
  author = {John W. Meriwether},
  title = {Measurement of weak airglow emissions with a programmable scanning spectrometer},
  journal = {Planetary and Space Science },
  year = {1979},
  volume = {27},
  number = {10},
  pages = {1221-1232},
  url = {http://www.sciencedirect.com/science/article/pii/0032063379901016},
  doi = {10.1016/0032-0633(79)90101-6}
}
Muldrew DB (1979), "Frequency asymmetry in the upshifted and downshifted plasma lines induced by an HF wave at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A6), pp. 2705-2714.
Abstract: The Langmuir waves responsible for the HF-wave-induced plasma lines observed during ionospheric heating experiments at Arecibo are generated and propagate to the point of detection, in field-aligned iontzation ducts. These Langmuir waves grow parametrically in the ducts at the height in the ionosphere at which the HF wave electric field is strongest. If it is assumed that there is a positive density gradient upward along the duct, then the observed ion acoustic frequency asymmetry between the upshifted and downshifted plasma lines can be explained. Agreement can be obtained between experimental and theoretical values for the frequency asymmetry and for the growth rates of the plasma line for a scale length along the magnetic field direction of about 40 km. A 40-km-scale length is less than that which would be expected during the day in the ambient plasma. However, it is probably not an unreasonable value for a duct under the influence of HF heating. A 40-km scale length also leads to a height differential of about 55 m between the points at which the waves responsible for the upshifted and downshifted plasma lines are detected by the Arecibo radar. The model also implies that the intensity of the upshifted plasma line would be greater than that for the downshifted plasma line.
BibTeX:
@article{Muldrew1979,
  author = {Muldrew, D. B.},
  title = {Frequency asymmetry in the upshifted and downshifted plasma lines induced by an HF wave at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A6},
  pages = {2705-2714},
  url = {http://dx.doi.org/10.1029/JA084iA06p02705},
  doi = {10.1029/JA084iA06p02705}
}
Richmond A and Roble R (1979), "Dynamic effects of aurora-generated gravity waves on the mid-latitude ionosphere", Journal of Atmospheric and Terrestrial Physics . Vol. 41, pp. 841-852.
Abstract: This paper gives a brief review of aurora-generated large-scale traveling ionospheric disturbances, and presents results of numerical simulations of one such event. Numerous observations and several theoretical studies have shown that large-scale gravity waves are generated in the high-latitude thermosphere during geomagnetic disturbances. Traveling to middle and low latitudes within the thermosphere, these waves interact with the ionosphere to produce large-scale traveling ionospheric disturbances. Relatively large amplitude waves generated by the Joule heating due to high-latitude ionospheric electric currents can propagate many thousands of kilometers at speeds of 300-1000 m/s, with periods of 30 min to several hours and horizontal wavelengths of thousands of kilometers. They affect the ionosphere not only by imparting vertical motion to the ionization, but also by altering the chemical reaction rates and heat transfer rates. Numerical simulations of the event of 18 September 1974 show that a Joule heat source of 2-4 â 10e15 J can generate gravity waves capable of reproducing the observed ionospheric disturbances at the Millstone Hill and Arecibo incoherent scatter observatories.
BibTeX:
@article{Richmond1979,
  author = {A.D. Richmond and R.G. Roble},
  title = {Dynamic effects of aurora-generated gravity waves on the mid-latitude ionosphere},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1979},
  volume = {41},
  pages = {841-852},
  url = {http://www.sciencedirect.com/science/article/pii/0021916979901272},
  doi = {10.1016/0021-9169(79)90127-2}
}
Rottger J, Rastogi PK and Woodman RF (1979), "High-resolution VHF radar observations of turbulence structures in the mesosphere", Geophysical Research Letters. Vol. 6(7), pp. 617-620.
Abstract: Results from a study of mesospheric turbulence, using a VHF radar with a height resolution of 150 m, are presented. Three types of turbulence structures have been identified: blobs, sheets and layers. Blobs and sheets occurred sporadically, predominantly at heights of 60–70 km. Above 70 km, layers thicker than 1 km were dominant, which were advected with the background wind. Velocity fluctuations in these structures were proportional to their thickness. The role of partial or Fresnel reflections is discussed and possibility of diffuse reflections below 70 km is noted. Problems in estimating transport coefficients from radar data are outlined.
BibTeX:
@article{Rottger1979,
  author = {Rottger, J. and Rastogi, P. K. and Woodman, R. F.},
  title = {High-resolution VHF radar observations of turbulence structures in the mesosphere},
  journal = {Geophysical Research Letters},
  year = {1979},
  volume = {6},
  number = {7},
  pages = {617-620},
  url = {http://dx.doi.org/10.1029/GL006i007p00617},
  doi = {10.1029/GL006i007p00617}
}
Trost TF (1979), "Electron concentrations in the E and upper D region at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A6), pp. 2736-2742.
Abstract: Electron concentrations in the D and E regions of the ionosphere have been measured by incoherent scatter radar from 130-km altitude down to the D region ledge with an altitude resolution of 900 m. The results are displayed as consecutive 5-min altitude profiles including sunrise, afternoon, and sunset periods. The ledge is found to undergo systematic variations between 80 and 90 km. A comparison with theoretical models for electron concentrations at 90 and 110 km reveals generally good agreement. However, at 90 km for ? ?60° the model values are high by a factor of 2, and at 110 km for ?=90° (sunrise and sunset) they are high by a factor of 4. The incoherent scatter results are consistent with rocket measurements and display well-known patterns of sporadic E as well as the postsunset valley in the E region.
BibTeX:
@article{Trost1979,
  author = {Trost, Thomas F.},
  title = {Electron concentrations in the E and upper D region at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A6},
  pages = {2736-2742},
  url = {http://dx.doi.org/10.1029/JA084iA06p02736},
  doi = {10.1029/JA084iA06p02736}
}
Vickrey JF, Swartz WE and Farley DT (1979), "Ion transport in the topside ionosphere at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A12), pp. 7307-7314.
Abstract: Incoherent scatter measurements at Arecibo can determine the separate vector drift velocitites of O+ and H+ ions in regions where the two species are mixed. At times the field-aligned drifts are actually in opposite directions in regions where the H+-O and O+-H charge exchange reactions are important. Here we present observations of the structure and dynamics of the topside ionosphere for 2 days, one in summer and one in winter. Measurements on August 15-16, 1976, showed upward daytime fluxes of both species totaling about 2-4 x 1e8 cm-2 s-1. During the night the net flux was generally downward, averaging about 1 x 1e8 cm-2 s-1. On January 15-16, 1977, the net upward daytime flux was smaller (~1 x 1e8 cm-2 s-1), with the proton flux remaining slightly downward. During the night of January 15-16 the average downward flux was again about 1 x 1e8 cm-2 s-1. The total upward flux through 754 km integrated from 0800 to 1600 LT on August 15-16 was ~8.6 x 1e12 cm-2, which was roughly 60% of the estimated total protonospheric content at 1500 LT. The total downward nighttime-integrated flux in the August observations was about 4 x 1e12 cm-2. The August data thus suggest a net (24 hour) upward flux. The January data are less complete but suggest a possible net downward flux. If these 2 days can be taken as being typical, they imply some interhemispheric transport from summer to winter.
BibTeX:
@article{Vickrey1979,
  author = {Vickrey, James F. and Swartz, Wesley E. and Farley, Donald T.},
  title = {Ion transport in the topside ionosphere at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A12},
  pages = {7307-7314},
  url = {http://dx.doi.org/10.1029/JA084iA12p07307},
  doi = {10.1029/JA084iA12p07307}
}
Vickrey JF, Swartz WE and Farley DT (1979), "Postsunset observations of ionospheric-protonospheric coupling at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 84(A4), pp. 1310-1314.
Abstract: The physical processes which couple the mid-latitude ionosphere and protonosphere are complicated during the postsunset period when temperatures are rapidly changing. We have studied these processes with incoherent scatter measurements of the electron densities and proton and O+ vertical velocities in the topside ionosphere with 10-min time resolution. Large velocity differences between the H+ and O+ ions in the topside ionosphere occur at times. The two vertical fluxes follow similar temporal trends at high altitudes, where the species have diffusive equilibrium profiles, both of which simply contract after sunset as the ionosphere cools. At lower altitudes, however, the charge exchange reactions can destroy the similarity in the temporal behavior of the two fluxes and can lead to ion counterstreaming at times. Therefore there is no simple relationship between the F2 region O+ flux and the total ion transport between the ionosphere and the protonosphere.
BibTeX:
@article{Vickrey1979a,
  author = {Vickrey, James F. and Swartz, Wesley E. and Farley, Donald T.},
  title = {Postsunset observations of ionospheric-protonospheric coupling at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A4},
  pages = {1310-1314},
  url = {http://dx.doi.org/10.1029/JA084iA04p01310},
  doi = {10.1029/JA084iA04p01310}
}
Walker JCG (1979), "Active experimentation with the ionospheric plasma", Reviews of Geophysics. Vol. 17(4), pp. 534-544.
BibTeX:
@article{Walker1979,
  author = {Walker, James C. G.},
  title = {Active experimentation with the ionospheric plasma},
  journal = {Reviews of Geophysics},
  year = {1979},
  volume = {17},
  number = {4},
  pages = {534-544},
  url = {http://dx.doi.org/10.1029/RG017i004p00534},
  doi = {10.1029/RG017i004p00534}
}
Yeh KC, Liu CH and Hearn AL (1979), "Propagation of gravity wave spectra in the thermosphere", Journal of Geophysical Research: Space Physics. Vol. 84(A3), pp. 834-838.
BibTeX:
@article{Yeh1979,
  author = {Yeh, K. C. and Liu, C. H. and Hearn, A. L.},
  title = {Propagation of gravity wave spectra in the thermosphere},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1979},
  volume = {84},
  number = {A3},
  pages = {834-838},
  doi = {10.1029/JA084iA03p00834}
}
Anonymous (1978), "New NAIC ionospheric facility planned near Arecibo", Eos, Transactions American Geophysical Union. Vol. 59(6), pp. 530-530.
Abstract: The National Astronomy and Ionosphere Center (NAIC) is building a High Frequency Ionospheric Modification Facility near Arecibo, Puerto Rico. When completed in June of next year, the facility will be able to deliver an effective power of 160 million W to the area of the ionosphere under study. This will be accomplished by an array of antennas covering more than 8 ha that will focus power from four 200,000-W transmitters.The new HF facility will replace an ionospheric heating apparatus now mounted occasionally on the main Arecibo telescope. The other device operates at lower power, requiring other experiments to stop while it is in operation.
BibTeX:
@article{Anonymous1978,
  author = {Anonymous},
  title = {New NAIC ionospheric facility planned near Arecibo},
  journal = {Eos, Transactions American Geophysical Union},
  year = {1978},
  volume = {59},
  number = {6},
  pages = {530-530},
  url = {http://dx.doi.org/10.1029/EO059i006p00530-02},
  doi = {10.1029/EO059i006p00530-02}
}
Behnke RA and Hagen JB (1978), "Incoherent scattering of radio waves by whistler mode oscillations in the ionosphere", Radio Science. Vol. 13(1), pp. 215-218.
Abstract: The received power spectrum in incoherent scatter can contain two sharp resonances removed from the center frequency. The first is due to ordinary electrostatic plasma oscillations and is known as the plasma line. The second depends on the presence of a magnetic field and corresponds to the high-frequency end of the whistler mode in magnetoionic theory. Here we report an experimental detection of this second resonance.
BibTeX:
@article{Behnke1978,
  author = {Behnke, R. A. and Hagen, J. B.},
  title = {Incoherent scattering of radio waves by whistler mode oscillations in the ionosphere},
  journal = {Radio Science},
  year = {1978},
  volume = {13},
  number = {1},
  pages = {215-218},
  url = {http://dx.doi.org/10.1029/RS013i001p00215},
  doi = {10.1029/RS013i001p00215}
}
Cragin BL, Fejer JA and Showen RL (1978), "Theory of coherent parametric instabilities excited by two or more pump waves", Geophysical Research Letters. Vol. 5(3), pp. 183-186.
Abstract: A method based on energy balance is used to obtain the thresholds of parametric instabilities of the ‘purely growing’ and ‘arithmetic mean’ varieties which can exist in a plasma irradiated by two or more electromagnetic pump waves. These instabilities produce growing standing electron plasma waves at frequencies satisfying either w = wi, where wi is the frequency of the ith pump wave, or w = (wi+wj)/2, where i and j correspond to two different pump waves. Additionally growing ion standing waves of zero frequency or of frequency (wi-wj)/2 are produced. These coherent instabilities are found to be coupled in a sense with the usual ‘decay’ instability and, in the case of three or more pump waves, with each other. The results of this investigation are applied to a recent ionospheric heating experiment described in a companion paper.
BibTeX:
@article{Cragin1978,
  author = {Cragin, B. L. and Fejer, J. A. and Showen, R. L.},
  title = {Theory of coherent parametric instabilities excited by two or more pump waves},
  journal = {Geophysical Research Letters},
  year = {1978},
  volume = {5},
  number = {3},
  pages = {183-186},
  url = {http://dx.doi.org/10.1029/GL005i003p00183},
  doi = {10.1029/GL005i003p00183}
}
Duncan LM and Behnke RA (1978), "Observations of Self-Focusing Electromagnetic Waves in the Ionosphere", Physical Review Letters. Vol. 41, pp. 998-1001. American Physical Society.
Abstract: Self-focusing of high-frequency electromagnetic radiation is observed to produce large-scale plasma striations in the ionosphere. Development of a new observational technique has allowed the first detailed study of the instability scale sizes and associated plasma movement. Experimental results are shown to support the theory of wave self-focusing through differential electron heating.
BibTeX:
@article{Duncan1978,
  author = {Duncan, L. M. and Behnke, R. A.},
  title = {Observations of Self-Focusing Electromagnetic Waves in the Ionosphere},
  journal = {Physical Review Letters},
  publisher = {American Physical Society},
  year = {1978},
  volume = {41},
  pages = {998-1001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.41.998},
  doi = {10.1103/PhysRevLett.41.998}
}
Fejer JA, Rinnert K and Woodman R (1978), "Detection of stimulated brillouin scattering by the Jicamarca Radar", Journal of Geophysical Research: Space Physics. Vol. 83(A5), pp. 2133-2136.
Abstract: Observations of weak stimulated Brillouin scattering with the 50-MHz incoherent scatter radar at Jicamarca are described. The nonlinear interaction of the upgoing radar wave with the downcoming waves, incoherently backscattered from greater heights, causes an asymmetry in the incoherent ‘ion’ backscatter spectrum. For a given antenna aperture this asymmetry increases with increasing power and decreasing frequency of the radar. The theoretically predicted effect was unambiguously verified, using 3-ms pulses and long integration time. Model calculations based on the theory presented show good agreement with the observations.
BibTeX:
@article{Fejer1978,
  author = {Fejer, J. A. and Rinnert, K. and Woodman, R.},
  title = {Detection of stimulated brillouin scattering by the Jicamarca Radar},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A5},
  pages = {2133-2136},
  url = {http://dx.doi.org/10.1029/JA083iA05p02133},
  doi = {10.1029/JA083iA05p02133}
}
Fukao S, Kato S, Yokoi S, Harper R, Woodman R and Gordon W (1978), "One full-day radar measurement of lower stratospheric winds over Jicamarca ", Journal of Atmospheric and Terrestrial Physics . Vol. 40(12), pp. 1331 - 1337.
Abstract: The lower stratospheric wind field is measured simultaneously at several altitudes for 24 h on 23-24 May 1974 using the Jicamarca radar in Peru. Maximum entropy spectral analysis is used to estimate echo power spectra from the measured autocorrelation functions which are truncated beyond the maximum time lag of 6.65 s. The fluctuating wind velocity is resolved into steady and tidal components. A vertical shear of 2-3 m s-1 km-1 is observed throughout the time of observation in the zonal wind. The mean zonal wind is in good agreement with the Lima-Callao radiosonde data obtained in the same month. A very large diurnal component, of amplitude 1-5 m s-1 is observed in the zonal wind in the lower stratosphere. However it appears that a semidiurnal oscillation below the tropopause is predominant.
BibTeX:
@article{Fukao1978,
  author = {S Fukao and S Kato and S Yokoi and R.M Harper and R.F Woodman and W.E Gordon},
  title = {One full-day radar measurement of lower stratospheric winds over Jicamarca },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {12},
  pages = {1331 - 1337},
  url = {http://www.sciencedirect.com/science/article/pii/0021916978900855},
  doi = {10.1016/0021-9169(78)90085-5}
}
Garrett HB and Forbes JM (1978), "Tidal structure of the thermosphere at equinox", Journal of Atmospheric and Terrestrial Physics . Vol. 40(6), pp. 657-668.
Abstract: The idealized ‘servo’ model of the ionospheric F2-layer, developed by Rishbeth, ganguly and Walker (1978), is used to simulate the observed behaviour of the daytime F2-peak at Arecibo for sunspot minimum. Taking the east-west electric field to be given by the observed plasma drift velocity perpendicular to the magnetic field, the theoretical equations are integrated using a trial-and-error approach to match the observed values of field-parallel plasma velocity, and the height and electron density of the F2-peak. From the calculation is determined empirically the meridional pressure-gradient force associated with the meridional neutral-air wind. The local time variation during the day is found to be consistent with the semidiurnal variation given by the MSIS atmospheric model of Hedinet al. (1977a, b), though with a phase shift that varies with season; on some days in the fall the pressure-gradient force displays a strong equatorward ‘surge’ in the evening. The values of F2-layer loss and diffusion coefficients needed to match the data are broadly consistent with the MSIS model. The analysis thus validates the MSIS model by way of ionospheric parameters quite independent of the data from which MSIS was originally derived.
BibTeX:
@article{Garrett1978,
  author = {Henry B. Garrett and Jeffrey M. Forbes},
  title = {Tidal structure of the thermosphere at equinox},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {6},
  pages = {657-668},
  url = {http://www.sciencedirect.com/science/article/pii/0021916980900653},
  doi = {10.1016/0021-9169(78)90123-X}
}
Gonzales CA, Kelley MC, Carpenter LA and Holzworth RH (1978), "Evidence for a magnetospheric effect on mid-latitude electric fields", Journal of Geophysical Research: Space Physics. Vol. 83(A9), pp. 4397-4399.
Abstract: Electric field measurements at Millstone Hill, which is located at a geographic latitude of 42.6°N and a geomagnetic latitude of 54.1°N, have been made during a time of extremely quiet geomagnetic activity in the 1800–0100 LT interval. The measured north-south electric field component was primarily southward (eastward F region drift) in this data set, whereas in previously published Millstone Hill data it was northward (westward drift). Furthermore, the quiet time data are in agreement with incoherent scatter and barium cloud results at similar geographic latitudes in the European sector which are at lower geomagnetic latitudes. We thus conclude that the electrical structure over Millstone Hill is almost always affected by magnetospheric effects and that only under very quiet conditions is the classical neutral wind dynamo evident. Several mechanisms for producing the magnetospheric effect are discussed.
BibTeX:
@article{Gonzales1978,
  author = {Gonzales, C. A. and Kelley, M. C. and Carpenter, L. A. and Holzworth, R. H.},
  title = {Evidence for a magnetospheric effect on mid-latitude electric fields},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A9},
  pages = {4397-4399},
  url = {http://dx.doi.org/10.1029/JA083iA09p04397},
  doi = {10.1029/JA083iA09p04397}
}
Harper R and Wand R (1978), "Coordinated tidal observations at Arecibo ", Journal of Atmospheric and Terrestrial Physics . Vol. 40(8), pp. 887-890.
BibTeX:
@article{Harper1978,
  author = {R.M Harper and R.H Wand},
  title = {Coordinated tidal observations at Arecibo },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {8},
  pages = {887-890},
  doi = {10.1016/0021-9169(78)90138-1}
}
Harper RM (1978), "Preliminary measurements of the ion component of the incoherent scatter spectrum in the 60-90 km region over Arecibo", Geophysical Research Letters. Vol. 5(9), pp. 784-786.
Abstract: Preliminary measurements of the ion component of the incoherent scatter spectrum are presented. The observations show qualitative agreement with theory if the effects of negative ions and experimental sources of spectral broadening are considered. The measurements indicate that neutral winds can be measured down to about 65 km during the daytime at Arecibo. Accuracies of 2.5 m/sec for the horizontal components, and 0.6 m/sec in the vertical component can be obtained below 80 km after one-half hour integration.
BibTeX:
@article{Harper1978a,
  author = {Harper, Robert M.},
  title = {Preliminary measurements of the ion component of the incoherent scatter spectrum in the 60-90 km region over Arecibo},
  journal = {Geophysical Research Letters},
  year = {1978},
  volume = {5},
  number = {9},
  pages = {784-786},
  url = {http://dx.doi.org/10.1029/GL005i009p00784},
  doi = {10.1029/GL005i009p00784}
}
Hearn AL and Yeh KC (1978), "A study of electron density spectra of traveling ionospheric disturbances", Journal of Geophysical Research: Space Physics. Vol. 83(A4), pp. 1442-1446.
Abstract: Special runs of the Arecibo incoherent scatter radar were made to provide high spatial resolution (8.7 km) and high temporal resolution (about 1 min) electron density data at discrete heights in the altitude range 200-500 km. The observed electron density fluctuations were spectrally analyzed and interpreted in terms of gravity wave induced traveling ionospheric disturbances. In many records, two kinds of persistent spectral dips for all heights were obtained. The first dip, occurring in the frequency range 0.025-0.055 min-1 (18- to 40-min period), is shown to be caused by the absence of ionospheric response when the gravity wave normal is perpendicular to the earth's magnetic field and therefore is of geomagnetic origin. The second dip, occurring in the frequency range 0.09-0.12 min-1 (8- to 11-min period), is shown to be related to high attenuation of those waves whose frequencies are slightly above the Brunt-VÄisÄlÄ frequency.
BibTeX:
@article{Hearn1978,
  author = {Hearn, A. L. and Yeh, K. C.},
  title = {A study of electron density spectra of traveling ionospheric disturbances},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A4},
  pages = {1442-1446},
  url = {http://dx.doi.org/10.1029/JA083iA04p01442},
  doi = {10.1029/JA083iA04p01442}
}
Mathews JD and Bekeny FS (1978), "The effect of negative ions on Thomson scattering in the presence of electron heating", Geophysical Research Letters. Vol. 5(11), pp. 925-927.
Abstract: The total Thomson scatter cross-section is considered in the presence of electron heating and as a function of the ratio of negative ion to electron number densities. For electron densities typical of the lower D region it is shown that the opposing factors of heating and negative ions lead to a local minimum of the cross-section in the experimentally accessible range of 1.5 <= Te/Ti <= 5. Electron heating is thus considered as a method for detecting negative ions and one early experiment may already have done so.
BibTeX:
@article{Mathews1978,
  author = {Mathews, J. D. and Bekeny, F. S.},
  title = {The effect of negative ions on Thomson scattering in the presence of electron heating},
  journal = {Geophysical Research Letters},
  year = {1978},
  volume = {5},
  number = {11},
  pages = {925-927},
  url = {http://dx.doi.org/10.1029/GL005i011p00925},
  doi = {10.1029/GL005i011p00925}
}
Mathews JD (1978), "The effect of negative ions on collision-dominated Thomson scattering", Journal of Geophysical Research: Space Physics. Vol. 83(A2), pp. 505-512.
BibTeX:
@article{Mathews1978a,
  author = {Mathews, John D.},
  title = {The effect of negative ions on collision-dominated Thomson scattering},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A2},
  pages = {505-512},
  doi = {10.1029/JA083iA02p00505}
}
Meriwether JW, Torr DG, Walker JCG and Nier AO (1978), "The O+(2P) emission at 7320 A in twilight", Journal of Geophysical Research: Space Physics. Vol. 83(A7), pp. 3311-3319.
BibTeX:
@article{Meriwether1978,
  author = {Meriwether, J. W. and Torr, D. G. and Walker, J. C. G. and Nier, A. O.},
  title = {The O+(2P) emission at 7320 A in twilight},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A7},
  pages = {3311-3319},
  doi = {10.1029/JA083iA07p03311}
}
Miller KL and Smith LG (1978), "Incoherent scatter radar observations of irregular structure in mid-latitude sporadic E layers", Journal of Geophysical Research: Space Physics. Vol. 83(A8), pp. 3761-3775.
Abstract: The structure of mid-latitude sporadic E layers has been investigated in a series of observations at the Arecibo Observatory. The basic experiment uses phase-coded pulses to measure the electron density profiles with a range resolution of 600 m while scanning the radar beam. The data from incoherent scatter are compared with simultaneous ionosonde observations to determine the source of the partial transparency of sporadic E layers to radio waves at frequencies between fbEs and ftEs. It is concluded that sporadic E layers contain electron density irregularities of sufficient intensity to account for the partially transparent echoes observed by the ionosonde. A feature that becomes immediately obvious in examining the data taken with the incoherent scatter radar is that sporadic E layers are as variable in structure as they are unpredictable in occurrence. Some have simple vertical profiles and are uniform in the horizontal plane, consistent with rocket observations; others have complex vertical and horizontal structure, as has been implied by the radio experiments. Wavelike structure in the electron density is present in many of the layers observed. Evidence is shown of the limiting of peak ionization density in a layer by turbulence generated in a Kelvin-Helmholtz instability. The possible proximity of a sporadic E layer to a critical level of a dominant gravity wave mode is discussed as a source of intense ionization irregularities. A possible irregular source of ionization from ablating meteors is also considered. It is shown that under specific conditions an ionized meteor trail can be converged by the action of the neutral wind into an irregularity of relatively small dimensions. It is concluded that the observations support the wind shear mechanism of formation of sporadic E layers when the combined effects of gravity waves, tides, and the irregular deposition of metallic ions are included.
BibTeX:
@article{Miller1978,
  author = {Miller, K. L. and Smith, L. G.},
  title = {Incoherent scatter radar observations of irregular structure in mid-latitude sporadic E layers},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A8},
  pages = {3761-3775},
  url = {http://dx.doi.org/10.1029/JA083iA08p03761},
  doi = {10.1029/JA083iA08p03761}
}
Muldrew DB (1978), "The role of field-aligned ionization irregularities in the generation of the HF-induced plasma line at Arecibo", Journal of Geophysical Research: Space Physics. Vol. 83(A6), pp. 2552-2560.
Abstract: By using the data from the July 1976 ionospheric modification experiments at Arecibo it was discovered that the Langmuir waves responsible for the enhanced plasma line are generated at the height in the ionosphere at which the Airy function, which describes the standing electric field of the high-frequency (HF) modifying wave near reflection, has its main maximum. It would be impossible for the enhanced Langmuir waves which backscatter the 430-MHz radar signal to exist at this height in a uniformly varying ionosphere. This implies that underdense ionization irregularities exist in the ionosphere that allow the Langmuir waves to be generated and to propagate to the appropriate ionization density for detection by the incoherent backscatter radar. This discovery puts a new light on the generation mechanism of the HF-enhanced plasma line, since up until now it has been implicitly assumed in theoretical work that the parametric decay process occurs in a uniformly varying ionosphere, that is, an ionosphere without irregularities. The ionization irregularities responsible for the HF-enhanced plasma line are probably field aligned with an electron density deviation decrease of about 4% or more and with a diameter between about 1 m and a few hundred meters. It is proposed that Langmuir waves are amplified parametrically as they propagate in the duct to where their wave normals are parallel to the radar beam. The observed frequency displacement from the radar frequency (430 MHz) of the parametric decay line at Arecibo is about fHF - 3.5 kHz, where fHF is the frequency of the HF heating wave (4–10 MHz). Numerical calculations for typical daytime conditions show that the maximum coupling between the HF and Langmuir waves occurs for a frequency offset between the two waves of about 3.4 kHz for the field-aligned irregularity or duct model, which is in good agreement with observations. The observed frequencies of the peaks in the HF-enhanced plasma line spectrum, which are displaced from 430 MHz ± fHF by approximately odd harmonics of the ion acoustic or offset frequency, can be explained with the duct model. The ‘broad bump’ observed in some plasma line spectra probably results from cascading of intense Langmuir waves which are produced parametrically and propagate approximately along the axis of the duct. It is proposed that the background or ‘immature’ spectrum may result from a four-wave decay process. The ‘overshoot’ phenomenon (intense plasma line signals occurring immediately after transmitter turn-on) may be due to the effects of HF heating on the ducts and on the ambient plasma.
BibTeX:
@article{Muldrew1978,
  author = {Muldrew, D. B.},
  title = {The role of field-aligned ionization irregularities in the generation of the HF-induced plasma line at Arecibo},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A6},
  pages = {2552-2560},
  url = {http://dx.doi.org/10.1029/JA083iA06p02552},
  doi = {10.1029/JA083iA06p02552}
}
Muldrew DB (1978), "Langmuir wave propagation and the enhanced plasma line in sporadic E", Journal of Geophysical Research: Space Physics. Vol. 83(A11), pp. 5207-5211.
Abstract: Observations of HF-induced plasma lines in blanketing sporadic E at Arecibo have been reported in the literature. The purely growing instability was found to be the probable source of the plasma lines, although the parametric decay instability could not be ruled out. It was also observed that the upshifted plasma lines tend to be much stronger than the downshifted plasma lines. A calculation of the purely growing and decay thresholds, using typical ray paths of the type thought to be responsible for the Arecibo observations, indicates that the purely growing instability is most likely responsible for the observed Es plasma lines. The purely growing threshold is smallest when it is determined by electron collisions rather than by the density gradient and when the wave normal of the unstable waves is nearly parallel to the earth's magnetic field. It is thus likely that the unstable Langmuir waves are generated where these conditions are satisfied and subsequently propagate to where they are observed by the radar. In order that these waves not be highly damped, the density gradient must be greater than about 10° off the vertical. This indicates that these waves propagate in ionization irregularities embedded in the Es layer. For irregularities with an upward component of density gradient directed north of the antimagnetic field direction, upshifted Es plasma lines would occur; otherwise, downshifted Es plasma lines would result. Since the former case covers a much larger range of angles than the latter case, it is not surprising that normally the upshifted Es plasma line is stronger than the downshifted Es plasma line.
BibTeX:
@article{Muldrew1978a,
  author = {Muldrew, D. B.},
  title = {Langmuir wave propagation and the enhanced plasma line in sporadic E},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A11},
  pages = {5207-5211},
  url = {http://dx.doi.org/10.1029/JA083iA11p05207},
  doi = {10.1029/JA083iA11p05207}
}
Oran ES, Palmadesso PJ and Ganguly S (1978), "Low-altitude plasma line anisotropy", Journal of Geophysical Research: Space Physics. Vol. 83(A5), pp. 2190-2194.
Abstract: Plasma line observations obtained from incoherent radar backscatter have been used as a ground-based method for deriving information about the size and anisotropy of the ionospheric photoelectron fluxes. In the past, data interpretation has been confined to altitudes above the F2 peak. Measurements below the F2 peak consistently show an anisotropy in the ratio of the downshifted to upshifted amplitudes of 20–50% when it is generally assumed that diffusion processes dominate. We describe calculations of the plasma line intensity which use a multiangle multienergy calculation of the photoelectron distribution function. The calculated electron flux exhibits a small low-altitude low-energy anisotropy which is reflected in the plasma line measurements. Given anisotropic elastic electron-neutral cross sections, the flux anisotropy arises when the local mean free path is of the order of the local scale height. The net effect is conversion of a spatial density inhomogeneity into a velocity distribution anisotropy.
BibTeX:
@article{Oran1978,
  author = {Oran, Elaine S. and Palmadesso, Peter J. and Ganguly, Suman},
  title = {Low-altitude plasma line anisotropy},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A5},
  pages = {2190-2194},
  url = {http://dx.doi.org/10.1029/JA083iA05p02190},
  doi = {10.1029/JA083iA05p02190}
}
Perkins FW and Roble RG (1978), "Ionospheric heating by radio waves: Predictions for Arecibo and the satellite power station", Journal of Geophysical Research: Space Physics. Vol. 83(A4), pp. 1611-1624.
Abstract: The effect of resistive heating by radio waves on ionospheric temperatures, electron densities, and airglow emissions is examined by using numerical ionospheric structure and heat balance codes. Two cases are studied: (1) a 3-GHz, 10-GW microwave beam from a proposed satellite power station and (2) 1-MW and 3-MW beams of 15-MHz radio waves launched by the Arecibo antenna. By intent, these two cases have similar intensities and geometries of resistive heating. The most dramatic heating effects are predicted to occur in the E region, where a thermal runaway will take place. The E region electron temperature will increase from 200°K to roughly 1000°K, and the E region electron density will increase by a factor of about 3. In the F region, where thermal conductivity plays an important role, temperature increases of 200°–500°K will appear along magnetic field lines passing through the radio wave beams. Enhanced emissions in airglow and molecular infrared lines will also occur. Radio wave heating, when combined with the diagnostic capabilities of the Arecibo incoherent scatter radar, will generate new opportunities to measure the rates of atomic physics processes and neutral atmosphere temperatures and composition at D and E region altitudes.
BibTeX:
@article{Perkins1978,
  author = {Perkins, F. W. and Roble, R. G.},
  title = {Ionospheric heating by radio waves: Predictions for Arecibo and the satellite power station},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A4},
  pages = {1611-1624},
  url = {http://dx.doi.org/10.1029/JA083iA04p01611},
  doi = {10.1029/JA083iA04p01611}
}
Rastogi R and Woodman R (1978), "VHF radio wave scattering due to range and frequency types of equatorial spread-F", Journal of Atmospheric and Terrestrial Physics . Vol. 40(4), pp. 485 - 491.
Abstract: Comparing vertical incidence ionograms during spread-F conditions at the equatorial station Huancayo and modified range time interrsity records of 50 MHz scatter echoes at Jicamarca, it has been shown that the range type of spread-F is very efficient for the back-scattering of VHF radio waves. On the otherhand, the frequency type of spread-F does not seem to produce strong echoes. It is suggested that the range type of spread-F ionogram is due to the reflection (w = wp) of radio waves from large scale irregularities with structure as small as 3 m below or near the base of the F-region The frequency type spread-F ionogram is suggested due to scattering from large scale irregularities with no 3 m counterpart situated around the region of peak ionisation density.
BibTeX:
@article{Rastogi1978,
  author = {R.G Rastogi and R.F Woodman},
  title = {VHF radio wave scattering due to range and frequency types of equatorial spread-F},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {4},
  pages = {485 - 491},
  url = {http://www.sciencedirect.com/science/article/pii/0021916978901824},
  doi = {10.1016/0021-9169(78)90182-4}
}
Rishbeth H, Ganguly S and Walker J (1978), "Field-aligned and field-perpendicular velocities in the ionospheric F2-layer", Journal of Atmospheric and Terrestrial Physics . Vol. 40(7), pp. 767 - 784.
Abstract: Incoherent scatter observations have shown that there is sometimes a detailed anticorrelation or ‘mirroring’ between V|| and Vp, the components of F2-layer plasma velocity parallel to and perpendicular to the geomagnetic field. In this paper we develop a simple theoretical model of the F2-layer and compute its response to applied perturbations of Vp, both steplike and oscillatory; in particular we investigate the phase and amplitude relationships between V|| and Vp resulting from ion-drag and plasma diffusion. For periods of a few hours, the oscillations of V|| lag behind exact anticorrelation with Vp by 0.1–0.2 cycle, but the time lags corresponding to these phase differences are only a fraction of 1 h and seem broadly compatible with observations previously reported from Arecibo and Malvern. We do not study the question of what causes the velocities to fluctuate in the first place.
BibTeX:
@article{Rishbeth1978,
  author = {H Rishbeth and S Ganguly and J.C.G Walker},
  title = {Field-aligned and field-perpendicular velocities in the ionospheric F2-layer},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {7},
  pages = {767 - 784},
  url = {http://www.sciencedirect.com/science/article/pii/0021916978900284},
  doi = {10.1016/0021-9169(78)90028-4}
}
Schunk RW and Nagy AF (1978), "Electron temperatures in the F region of the ionosphere: Theory and observations", Reviews of Geophysics. Vol. 16(3), pp. 355-399.
Abstract: The theory and observations relating to electron temperatures in the F region of the ionosphere are reviewed. The review is divided into three basic parts. In the first part the theory concerning electron heating, cooling, and energy transport processes is reviewed, and all the relevant expressions are updated. In the second part the behavior of F region electron temperatures, as measured by satellites, rockets, and incoherent scatter radars, is discussed. This portion covers electron temperature variations with altitude, latitude, local time, season, geomagnetic activity, and solar cycle. The third part is primarily devoted to a discussion of the various attempts to compare measured and calculated F region electron temperatures.
BibTeX:
@article{Schunk1978,
  author = {Schunk, R. W. and Nagy, Andrew F.},
  title = {Electron temperatures in the F region of the ionosphere: Theory and observations},
  journal = {Reviews of Geophysics},
  year = {1978},
  volume = {16},
  number = {3},
  pages = {355-399},
  url = {http://dx.doi.org/10.1029/RG016i003p00355},
  doi = {10.1029/RG016i003p00355}
}
Showen RL, Duncan LM and Cragin BL (1978), "Observations of plasma instabilities in a multiple pump ionospheric heating experiment", Geophysical Research Letters. Vol. 5(3), pp. 187-190.
Abstract: The response of the ionospheric plasma to multiple pumps is seen in the enhancements of the incoherent scatter plasma line. Two strong HF pumps are transmitted, along with weaker sidebands. The two main pumps have a frequency separation ranging from 0 to 7 kHz. At zero frequency separation the standard decay and purely growing mode instabilities are observed. When two pumps are present, the normal decay instability usually disappears, and is replaced by strong oscillations at the pump frequencies plus features half way between pairs of pumps. These "arithmetic mean" peaks appear in most of the cases observed. The weak transmitted sidebands seem to influence greatly the observed spectra; the theory is treated in a companion paper.
BibTeX:
@article{Showen1978,
  author = {Showen, Robert L. and Duncan, L. M. and Cragin, B. L.},
  title = {Observations of plasma instabilities in a multiple pump ionospheric heating experiment},
  journal = {Geophysical Research Letters},
  year = {1978},
  volume = {5},
  number = {3},
  pages = {187-190},
  url = {http://dx.doi.org/10.1029/GL005i003p00187},
  doi = {10.1029/GL005i003p00187}
}
Sipler DP and Biondi MA (1978), "Arecibo Ionospheric Modification Experiments—Correlation of 630.0-nm intensity suppressions and enhancements with backscatter radar data", Journal of Geophysical Research: Space Physics. Vol. 83(A4), pp. 1519-1523.
Abstract: Simultaneous filter photometer and backscatter radar measurements during RF heating of the ionosphere (ionospheric modification) at Arecibo, Puerto Rico, in 1975 are used to relate 630.0-nm nightglow intensity modifications to F region changes. The observed ohmic heating of the F region electrons accounts for the measured 630.0-nm intensity suppression resulting from reduced O(¹D) production by O2+ ion-electron recombination. The 630.0-nm intensity enhancements caused by impact excitation of oxygen atoms by fast electrons are associated with the presence of strong plasma instabilities, as is manifested by large backscattered power from the heating wave absorption region. The variability in the RF heating wave-ionospheric plasma coupling is demonstrated by observations of suppression, no change, and enhancement of 630.0-nm nightglow intensity during similar heating cycles over a 2-hour period.
BibTeX:
@article{Sipler1978,
  author = {Sipler, Dwight P. and Biondi, Manfred A.},
  title = {Arecibo Ionospheric Modification Experiments—Correlation of 630.0-nm intensity suppressions and enhancements with backscatter radar data},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A4},
  pages = {1519-1523},
  url = {http://dx.doi.org/10.1029/JA083iA04p01519},
  doi = {10.1029/JA083iA04p01519}
}
Smith P and Bewtra N (1978), "Charge exchange lifetimes for ring current ions", Space Science Reviews. Vol. 22(3), pp. 301-318.
BibTeX:
@article{Smith1978,
  author = {Smith, PaulH. and Bewtra, N.K.},
  title = {Charge exchange lifetimes for ring current ions},
  journal = {Space Science Reviews},
  year = {1978},
  volume = {22},
  number = {3},
  pages = {301-318},
  doi = {10.1007/BF00239804}
}
Sobral JHA (1978), "Optical measurements of the quenching coefficient of the O(1D) state by collisions with ambient molecules utilizing the ionospheric heating experiment", Journal of Atmospheric and Terrestrial Physics . Vol. 40(8), pp. 945-948.
BibTeX:
@article{Sobral1978,
  author = {Jose Humberto Andrade Sobral},
  title = {Optical measurements of the quenching coefficient of the O(1D) state by collisions with ambient molecules utilizing the ionospheric heating experiment},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1978},
  volume = {40},
  number = {8},
  pages = {945-948},
  doi = {10.1016/0021-9169(78)90147-2}
}
Sobral JHA, Carlson HC, Farley DT and Swartz WE (1978), "Nighttime dynamics of the F region near Arecibo as mapped by airglow features", Journal of Geophysical Research: Space Physics. Vol. 83(A6), pp. 2561-2566.
Abstract: Red line (6300 å) airglow measurements have been made at Arecibo (29°N geomagnetic latitude) by using a scanning photometer in order to determine the direction and phase velocity of propagation of major airglow enhancements, which incoherent scatter and ionosonde measurements have shown are in turn associated with pronounced descents of the F region. The scans were made in the N-S direction on 13 nights and in the E-W direction on five nights. The most common type of descent is observed first to the south and then progresses northward, with an apparent phase velocity of the order of 300 m/s. Neutral winds are apparently the cause of this type of descent, and future models of upper atmospheric diurnal pressure patterns should be consistent with this large-scale regular nighttime feature. Descents of the equatorial ionosphere were observed from ionogram data to occur 2–3 hours earlier than this type of airglow enhancement at Arecibo. The equatorial descents are caused by electric fields and do not directly drive the descent at Arecibo, but both are ultimately driven by the global neutral pressure gradients and resulting winds. A second type of enhancement, seen on occasion and probably due to traveling ionospheric disturbances, was observed to travel from north to south with comparable velocities. A third type does not seem to correspond to anything previously reported in the literature. Sudden descents lasting an hour or so sometimes occurred nearly simultaneously over regions extending at least 1000 km in the N-S or E-W direction.
BibTeX:
@article{Sobral1978a,
  author = {Sobral, J. H. A. and Carlson, H. C. and Farley, D. T. and Swartz, W. E.},
  title = {Nighttime dynamics of the F region near Arecibo as mapped by airglow features},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A6},
  pages = {2561-2566},
  url = {http://dx.doi.org/10.1029/JA083iA06p02561},
  doi = {10.1029/JA083iA06p02561}
}
Tepley CA and Mathews JD (1978), "Preliminary measurements of ion-neutral collision frequencies and mean temperatures in the Arecibo 80- to 100-km altitude region", Journal of Geophysical Research: Space Physics. Vol. 83(A7), pp. 3299-3302.
Abstract: The Arecibo 430-MHz radar was used in October and November of 1974 to make preliminary measurements of collision-dominated Thomson scatter spectra in the 80- to 100-km altitude region. A technique for interpreting the altitude variations of the collision-dominated spectra is presented. This technique employs the relaxable assumptions of an isothermal atmosphere and ion-neutral collision frequency variation with altitude according to the Barometric Law. Within these assumptions, temperature, collision frequencies, and total neutral number densities are inferred. We found the winter tropical mesopause region to be slightly warmer and denser than is indicated in the Cira (1972) standard atmosphere.
BibTeX:
@article{Tepley1978,
  author = {Tepley, C. A. and Mathews, J. D.},
  title = {Preliminary measurements of ion-neutral collision frequencies and mean temperatures in the Arecibo 80- to 100-km altitude region},
  journal = {Journal of Geophysical Research: Space Physics},
  year = {1978},
  volume = {83},
  number = {A7},
  pages = {3299-3302},
  url = {http://dx.doi.org/10.1029/JA083iA07p03299},
  doi = {10.1029/JA083iA07p03299}
}
Walker JCG (1978), "Space science without rockets: Measurement of ionospheric properties at the Arecibo Observatory", Eos, Transactions American Geophysical Union. Vol. 59(4), pp. 180-189.
Abstract: The nature of research in the atmospheric sciences is changing rapidly in what may be thought of as three distinct revolutions, each involving a different level of the atmosphere and each in a different stage of development. The first revolution, in meteorology and climatology, has been brought about by weather satellites, giant computing facilities, and carefully coordinated international research programs; it is already well advanced. Public concern over the future of the ozone layer has spawned the second revolution, which involves the middle atmosphere (the region between about 15 and 100 km in height); this revolution has just begun. The nature of the third revolution is only now becoming apparent. It concerns the study of the atmosphere above about 100 km, a study that I shall call ionospheric physics.
BibTeX:
@article{Walker1978,
  author = {Walker, James C. G.},
  title = {Space science without rockets: Measurement of ionospheric properties at the Arecibo Observatory},
  journal = {Eos, Transactions American Geophysical Union},
  year = {1978},
  volume = {59},
  number = {4},
  pages = {180-189},
  url = {http://dx.doi.org/10.1029/EO059i004p00180},
  doi = {10.1029/EO059i004p00180}
}
Woodman RF and Basu S (1978), "Comparison between in-situ spectral measurements of F-region irregularities and backscatter observations at 3 m wavelength", Geophysical Research Letters. Vol. 5(10), pp. 869-872.
Abstract: In situ measurements of equatorial electron density irregularities in the F-region by rockets and satellites have yielded a power-law form of one-dimensional wave number spectrum of spectral index 2 in a direction transverse to the magnetic field over a scale size range of several km to several tens of m. Equatorial scintillation measurements in the WHF/UHF band which are most sensitive to irregularities of several km to several hundred m are consistent with the in situ spectral results. The backscatter measurements made at Jicamarca at 50 MHz provide an additional measurement of the spectral power at 3m wavelength. Computations are presented for the backscatter intensity expected from irregularities with power law spectrum in the transverse direction but which are infinitely elongated along the magnetic field. The computed intensity is compared with actual backscatter measurements and correlated scintillation observations. It is found that in order to reconcile the backscatter measurements with the simultaneous VHF/UHF scintillation observations a gaussian type cut-off of the power-law spectrum is necessary at m wavelengths near the O+ ion gyro-radius.
BibTeX:
@article{Woodman1978,
  author = {Woodman, R. F. and Basu, Sunanda},
  title = {Comparison between in-situ spectral measurements of F-region irregularities and backscatter observations at 3 m wavelength},
  journal = {Geophysical Research Letters},
  year = {1978},
  volume = {5},
  number = {10},
  pages = {869-872},
  url = {http://dx.doi.org/10.1029/GL005i010p00869},
  doi = {10.1029/GL005i010p00869}
}
Aso T, Kato S and Harper RM (1977), "Arecibo Middle Atmosphere Experiment", Geophysical Research Letters. Vol. 4(1), pp. 10-12.
Abstract: An experiment was performed using the powerful radar at Arecibo (18°N 67°E, 51° dip) to look for stratospheric and mesospheric echoes in the UHF frequency band. Strong echoes were returned from the stratospheric region, whereas no distinct returns were obtained from mesospheric heights. These results, when compared to those reported for the VHF radar at Jicamarca, support wavenumber dependences of the scattering mechanisms, such that scattering due to neutral air turbulence should be more effective at UHF frequencies than at VHF in the stratosphere, while the reverse should be true in the mesosphere. The results suggest the feasibility of utilizing the present UHF incoherent scatter radar for remote sensing of winds in the stratosphere.
BibTeX:
@article{Aso1977,
  author = {Aso, T. and Kato, S. and Harper, R. M.},
  title = {Arecibo Middle Atmosphere Experiment},
  journal = {Geophysical Research Letters},
  year = {1977},
  volume = {4},
  number = {1},
  pages = {10-12},
  url = {http://dx.doi.org/10.1029/GL004i001p00010},
  doi = {10.1029/GL004i001p00010}
}
Benson RF, Bauer P, Brace LH, Carlson HC, Hagen J, Hanson WB, Hoegy WR, Torr MR, Wand RH and Wickwar VB (1977), "Electron and Ion Temperatures - A Comparison of Ground-Based Incoherent Scatter and AE-C Satellite Measurements", Journal of Geophysical Research. Vol. 82(1), pp. 36-42.
BibTeX:
@article{Benson1977,
  author = {Benson, R. F. and P. Bauer and L. H. Brace and H. C. Carlson and J. Hagen and W. B. Hanson and W. R. Hoegy and M. R. Torr and R. H. Wand and V. B. Wickwar},
  title = {Electron and Ion Temperatures - A Comparison of Ground-Based Incoherent Scatter and AE-C Satellite Measurements},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {1},
  pages = {36-42},
  doi = {10.1029/JA082i001p00036}
}
Carlson HC and Duncan LM (1977), "HF excited instabilities in space plasmas", Radio Science. Vol. 12(6), pp. 1001-1013.
Abstract: Radio waves delivering sufficiently strong electric field strengths to a plasma can excite parametric instabilities in the plasma for properly matched conditions. Technology had advanced by 1970 to the stage where this could be effected in the ionospheric plasma by ground-based installations. High-power HF transmitters, in the nominal 3–12 MHz range, deposited substantial energy in the ionospheric plasma, raising thermal plasma temperatures, exciting a rich spectrum of waves and irregularities in the plasma, and leading to extrathermal electron fluxes sensible to energies of the order of 10 eV. The results of experiments utilizing such controlled effects on the ionospheric plasma as diagnosed by remote sensors in a very broad RF band as well as in the optical band, have been followed with great interest by workers in fields as diverse as nuclear fusion, plasma physics, communications, and aeronomy from ionospheric thermal balance to spread-F. Significant checks on and advances in relevant theory have already accrued, but much of the potential is yet untapped. Experiments of this nature can also be performed from space vehicles. These could not only supplement studies possible from ground-based sites, but also permit some qualitative advances by virtue of the spacial trajectory and in situ nature unique to the vehicle. A number of specific features of the phenomena bear importantly on the practicality of such an experiment, including: instability rise times and decay times, irregularity scale sizes, power dependence, frequency spectra and implied physics, thermal plasma time constants, and field geometry dependences. The results of ground-based “HF heating experiments,” particularly as diagnosed by incoherent scatter techniques, are reviewed with this in mind.
BibTeX:
@article{Carlson1977,
  author = {Carlson, H. C. and Duncan, L. M.},
  title = {HF excited instabilities in space plasmas},
  journal = {Radio Science},
  year = {1977},
  volume = {12},
  number = {6},
  pages = {1001-1013},
  url = {http://dx.doi.org/10.1029/RS012i006p01001},
  doi = {10.1029/RS012i006p01001}
}
Harper RM (1977), "A comparison of ionospheric currents, magnetic variations, and electric fields at Arecibo", Journal of Geophysical Research. Vol. 82(22), pp. 3233-3242.
Abstract: Ionospheric currents calculated from incoherent scatter measurements at Arecibo are compared to ground magnetic variations at San Juan and to electric fields measured in the F region for two slightly disturbed periods and one very disturbed period, comprising a total of 7 days of data. The measurements indicate that the currents primarily responsible for the ground magnetic variations were flowing in the ionosphere on the slightly disturbed days. On the very disturbed days the variation in the horizontal intensity appears to be primarily due to an asymmetric ring current of magnetospheric origin. The eastward wind had to be modeled above 130 km in the calculations. A semidiurnal S2,2 wind model consistent with the measured southward winds drives southward currents that produce a total D variation of 20–40 ? with approximately the observed phase, indicating that the S2,2 component should be included in theoretical Sq calculations. A diurnal component also appears to be necessary if the D variation is to be well reproduced. The electrostatic field was found to drive about as much net horizontal current as the neutral winds. The horizontal components of the electrostatic field tended to be perpendicular to the calculated ionospheric currents on all days.
BibTeX:
@article{Harper1977,
  author = {Harper, R. M.},
  title = {A comparison of ionospheric currents, magnetic variations, and electric fields at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {22},
  pages = {3233-3242},
  url = {http://dx.doi.org/10.1029/JA082i022p03233},
  doi = {10.1029/JA082i022p03233}
}
Harper RM (1977), "Tidal winds in the 100- to 200-km region at Arecibo", Journal of Geophysical Research. Vol. 82(22), pp. 3243-3250.
Abstract: Neutral wind observations over the 100- to 200-km height region at Arecibo are presented for a summer, an equinox, and a winter period. Observations confirm that the wind below 110 km is predominately diurnal, with a vertical wavelength of about 20 km, and can be identified with the S1,1 mode. This tide reaches amplitudes of 100 m/s near 100 km but exhibits large day to day and seasonal variation. The vertical energy flux associated with the S1,1 mode is of the order of 0.25 erg/cm²/s at 100 km. A semidiurnal oscillation dominates the wind field from about 115 km to at least 170 km during the summer and equinox observations. A nighttime intermediate layer of enhanced electron density consistently descends through the F1 valley in the postsunset hours along the convergent null in Vz associated with the semidiurnal winds. The S2,2 mode dominates the semidiurnal oscillation above 125 km during these periods, reaching a maximum amplitude of 90 m/s at 153 km. Higher-order modes contribute to the semidiurnal oscillation principally below 125 km during spring and summer but appear to dominate at all heights in the winter observations, when the S2,2 mode appears to be largely absent. The vertical energy flux associated with the S2,2 mode is at least an order of magnitude less than that associated with the S1,1 mode.
BibTeX:
@article{Harper1977a,
  author = {Harper, R. M.},
  title = {Tidal winds in the 100- to 200-km region at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {22},
  pages = {3243-3250},
  url = {http://dx.doi.org/10.1029/JA082i022p03243},
  doi = {10.1029/JA082i022p03243}
}
Harper R and Walker J (1977), "Comparison of electrical conductivities in the E-AND F-regions of the nocturnal ionosphere ", Planetary and Space Science . Vol. 25(2), pp. 197-199.
Abstract: Experimental results from Arecibo indicate that on the average the height integrated F-region Pedersen conductivity is slightly greater than the height integrated E-region Pedersen conductivity, while the height integrated Hall conductivity exceeds either of the Pedersen conductivities by a factor of about 2. However, the conductivities can differ substantially from the average values on any given night.
BibTeX:
@article{Harper1977b,
  author = {R.M. Harper and J.C.G. Walker},
  title = {Comparison of electrical conductivities in the E-AND F-regions of the nocturnal ionosphere },
  journal = {Planetary and Space Science },
  year = {1977},
  volume = {25},
  number = {2},
  pages = {197-199},
  url = {http://www.sciencedirect.com/science/article/pii/0032063377900265},
  doi = {10.1016/0032-0633(77)90026-5}
}
Harper R and Woodman R (1977), "Preliminary multiheight radar observations of waves and winds in the mesosphere over Jicamarca", Journal of Atmospheric and Terrestrial Physics . Vol. 39(9–10), pp. 959 - 963.
Abstract: The Jicamarca Radio Observatory receives strong radar echoes from the mesosphere. This paper reports preliminary results of simultaneous measurements of echo power, radial velocity, and spectral width at 12 mesospheric heights spaced at 2.5 km intervals over the 60–90 km region. These results indicate that the echoing regions are not continuous in space; on time scales of an hour strong echoes tend to be received from well defined heights. Velocity oscillations are highly correlated at nearby altitudes, while velocities at altitudes separated by more than 5 km show little or no correlation. There is no clear upward or downward wave-like progression in either the velocities or echo power; rather, the dominant periodicities of the oscillations are observed to change with altitude. Correlations between the velocity of the medium, the echo power, and the spectral width at gravity wave time scales point to short period gravity waves as an energy source for turbulence at mesospheric altitudes.
BibTeX:
@article{Harper1977c,
  author = {R.M. Harper and R.F. Woodman},
  title = {Preliminary multiheight radar observations of waves and winds in the mesosphere over Jicamarca},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1977},
  volume = {39},
  number = {9–10},
  pages = {959 - 963},
  url = {http://www.sciencedirect.com/science/article/pii/0021916977900034},
  doi = {10.1016/0021-9169(77)90003-4}
}
Hearn AL and Yeh KC (1977), "Medium scale TID's and their associated internal gravity waves as seen through height-dependent electron density power spectra", Journal of Geophysical Research. Vol. 82(32), pp. 4983-4990.
Abstract: Fluctuations of the F region electron density in the gravity wave period range have been monitored by using the Arecibo incoherent scatter radar. The radar was pointed in the vertical direction, and a transmitted pulse 50 µs in length was used to provide 1-min time resolution time series of 4- to 30-hour duration at several altitudes in the altitude range of 197.85–485.85 km. Spectral analysis has been performed on 4-hour segments of these time series. Spectral peaks recurring at a nearly constant frequency over the entire altitude range of this experiment were taken to be the ionospheric response due to the passage of an internal gravity wave. Relative phase information at the corresponding frequency can be obtained from the time series data. This response in magnitude and phase was fit to an atmospheric model to yield the parameters of causative internal gravity waves. Two cases are presented and compared to a dispersion relation, generally good agreement being obtained. Discrepancies in the agreement for the imaginary part of the wave number can be attributed to inaccuracies in the model atmosphere, but a disagreement found between the experimental results for the real part of the wave number and the dispersion relation at altitudes above the electron density maximum is of unknown origin.
BibTeX:
@article{Hearn1977,
  author = {Hearn, A. L. and Yeh, K. C.},
  title = {Medium scale TID's and their associated internal gravity waves as seen through height-dependent electron density power spectra},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {32},
  pages = {4983-4990},
  url = {http://dx.doi.org/10.1029/JA082i032p04983},
  doi = {10.1029/JA082i032p04983}
}
Ho M and Moorcroft D (1977), "Composition, temperatures and electron loss coefficient of the topside ionosphere over Arecibo", Journal of Atmospheric and Terrestrial Physics . Vol. 39, pp. 1317-1324.
BibTeX:
@article{Ho1977,
  author = {M.C Ho and D.R Moorcroft},
  title = {Composition, temperatures and electron loss coefficient of the topside ionosphere over Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1977},
  volume = {39},
  pages = {1317-1324},
  doi = {10.1016/0021-9169(77)90083-6}
}
Mahajan K (1977), "Models of electron temperature in the ionospheric F-region using electron density height profiles", Journal of Atmospheric and Terrestrial Physics . Vol. 39(5), pp. 637-639.
Abstract: Models of electron temperature in the ionospheric F-region are presented for low and medium solar activity conditions. The low solar activity models are based upon the incoherent-scatter radar measurements at Arecibo during 1965–1966. The medium solar activity models are based upon the incoherent-scatter radar measurements at St. Santin during 1967–1968. These models have been constructed from the empirical relations between electron concentration and electron temperature given by Mahajan (1967a) and Lejeune and Waldteufel (1970). Comparisons of electron temperature calculated from the models with those observed from incoherent-scatter radars and Langmuir probes show good agreement.
BibTeX:
@article{Mahajan1977,
  author = {K.K Mahajan},
  title = {Models of electron temperature in the ionospheric F-region using electron density height profiles},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1977},
  volume = {39},
  number = {5},
  pages = {637-639},
  url = {http://www.sciencedirect.com/science/article/pii/0021916977900757},
  doi = {10.1016/0021-9169(77)90075-7}
}
Meriwether JW and Walker JCG (1977), "Intensity of the first negative band system of nitrogen in the night sky over Arecibo", Journal of Geophysical Research. Vol. 82(13), pp. 1855-1858.
Abstract: The 0–1 band (4278 å) of the first negative system of nitrogen has been measured in the spectrum of the night sky with a 1-m Ebert-Fastie spectrophotometer at the Arecibo Observatory. Integration periods of approximately 4 hours were needed to provide an adequate ratio of signal to noise. The measured spectra were corrected for blending with the 2–9 Herzberg band of oxygen at 4281 å. The intensity of the 4278-å radiation measured on 6 nights in late March 1976 was about 0.1 R. Little variation in the intensity was observed from night to night. We suggest that most of the observed emission was produced not by charged particle bombardment of the atmosphere but by photoionization of N2 by scattered solar radiation at 304 and 584 å.
BibTeX:
@article{Meriwether1977,
  author = {Meriwether, John W. and Walker, James C. G.},
  title = {Intensity of the first negative band system of nitrogen in the night sky over Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {13},
  pages = {1855-1858},
  url = {http://dx.doi.org/10.1029/JA082i013p01855},
  doi = {10.1029/JA082i013p01855}
}
Muldrew DB and Showen RL (1977), "Height of the HF-enhanced plasma line at Arecibo", Journal of Geophysical Research. Vol. 82(29), pp. 4793-4804.
Abstract: In an ionospheric modification experiment at Arecibo in July 1976 it was discovered that the height of the enhanced plasma line due to photoelectrons does not agree with the height of the enhanced plasma line due to the HF heating wave. The properties of the Barker decoder, used in the experiment, indicate that the photoelectron enhanced plasma line occurs at the height expected by theory for a uniformly varying ionosphere, whereas the observed HF enhanced plasma line occurs a few kilometers above this height. The Langmuir waves responsible for the observed HF plasma line at Arecibo probably exist near the largest or first maximum of the Airy function, which describes the standing HF electric field. This is about 200 m below the heater wave reflection height. This observation requires that the Langmuir waves responsible for the HF-induced plasma line be generated in ionization irregularities and subsequently propagate in the irregularities to the appropriate plasma frequency for detection by the Arecibo radar.
BibTeX:
@article{Muldrew1977,
  author = {Muldrew, D. B. and Showen, R. L.},
  title = {Height of the HF-enhanced plasma line at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {29},
  pages = {4793-4804},
  url = {http://dx.doi.org/10.1029/JA082i029p04793},
  doi = {10.1029/JA082i029p04793}
}
Newton GP, Walker JCG and Mantas GP (1977), "Effects of soft electron precipitation on the distribution of vibrational energy of N2", Journal of Geophysical Research. Vol. 82(1), pp. 187-190.
Abstract: We have investigated the direct effect of soft electron precipitation on the nitrogen vibrational distribution and on the rate coefficient for the ion-atom interchange reaction between O+ and N2 using a spectrum of the precipitating electrons characteristic of the dayside cusp region. Substantial increases in the nitrogen vibrational temperature and in the rate of the O+ destruction reaction do not occur unless the flux of incident electrons is as large as 1012 cm-2 s-1. For such large fluxes, departures of the vibrational distribution from a Boltzmann distribution have a significant effect on the rate coefficient. Incident fluxes less than 1011 cm-2 s-1, such as are usually observed, have little direct effect on nitrogen vibration, although the indirect effect resulting from enhanced electron temperatures might be important.
BibTeX:
@article{Newton1977,
  author = {Newton, George P. and Walker, James C. G. and Mantas, George P.},
  title = {Effects of soft electron precipitation on the distribution of vibrational energy of N2},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {1},
  pages = {187-190},
  url = {http://dx.doi.org/10.1029/JA082i001p00187},
  doi = {10.1029/JA082i001p00187}
}
Orsini N, Torr DG, Torr MR, Brinton HC, Brace LH, Nier AO and Walker JCG (1977), "Quenching of metastable 2D oxygen ions in the thermosphere by atomic oxygen", Journal of Geophysical Research. Vol. 82(29), pp. 4829-4833.
Abstract: The Atmosphere Explorer (AE) satellites have acquired a large data base of aeronomic parameters measured over a wide range of geophysical conditions over the past 3 years. These data have already been used in a straightforward way to determine rate coefficients for many thermospheric reactions. In this paper we report the use of the AE data in a new way to simulate laboratory-type control of variables to determine the rate coefficient for the reaction [O+(2D)+O -- O+(4S)+O] . By appropriate selection of data we succeed in eliminating the effects of three uncertain rate coefficients on our determination; these are recombination of N2+ and electron and N2 quenching of O+(²D). We find that k < 3 â 10-11 cm¨ s-1. This upper limit is a factor of 3 smaller than an earlier estimate of the rate coefficient made from AE data. The difference in results is attributed to a large uncertainty in the dependence of N2+ recombination on vibrational excitation which affected the earlier work. Our technique demonstrates how the atmosphere can be used successfully as a laboratory to study atomic and molecular processes.
BibTeX:
@article{Orsini1977,
  author = {Orsini, N. and Torr, D. G. and Torr, M. R. and Brinton, H. C. and Brace, L. H. and Nier, A. O. and Walker, J. C. G.},
  title = {Quenching of metastable 2D oxygen ions in the thermosphere by atomic oxygen},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {29},
  pages = {4829-4833},
  url = {http://dx.doi.org/10.1029/JA082i029p04829},
  doi = {10.1029/JA082i029p04829}
}
Thuillier G, Falin J and Barlier F (1977), "Global experimental model of the exospheric temperature using optical and incoherent scatter measurements", Journal of Atmospheric and Terrestrial Physics . Vol. 39, pp. 1195-1202.
BibTeX:
@article{Thuillier1977,
  author = {G. Thuillier and J.L. Falin and F. Barlier},
  title = {Global experimental model of the exospheric temperature using optical and incoherent scatter measurements},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1977},
  volume = {39},
  pages = {1195-1202},
  doi = {10.1016/0021-9169(77)90028-9}
}
Woodman RF, Rastogi RG and Calderon C (1977), "Solar cycle effects on the electric fields in the equatorial ionosphere", Journal of Geophysical Research. Vol. 82(32), pp. 5257-5261.
Abstract: The horizontal east-west electric fields in the equatorial F region are estimated by using the vertical electron drift data over Jicamarca, Peru. The reversal of the electric field from west to east near the sunrise hours is not affected by solar cycle, but the evening reversal is found to occur about 1 hour earlier during low-sunspot years. The average value of the electric field magnitude during noon hours is the same for different portions of the solar cycle; however, the day to day variation is larger during years of low solar activity. The postsunset increase of the electric field is characteristic of high-sunspot periods only. Abnormal reversals of the electric field are seen on some occasions during the daytime hours, and these events are associated with the equatorial counter electrojets.
BibTeX:
@article{Woodman1977,
  author = {Woodman, R. F. and Rastogi, R. G. and Calderon, C.},
  title = {Solar cycle effects on the electric fields in the equatorial ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1977},
  volume = {82},
  number = {32},
  pages = {5257-5261},
  url = {http://dx.doi.org/10.1029/JA082i032p05257},
  doi = {10.1029/JA082i032p05257}
}
Zinchenko G and Nisbet J (1977), "Coupling of mid-latitude spread-F between conjugate stations", Journal of Atmospheric and Terrestrial Physics. Vol. 39(4), pp. 469-474.
Abstract: It appears that spread-F is associated with electric field perturbations and that above a certain scale length transverse electric fields are coupled between hemispheres. Two stations, Puerto Rico and Port Stanley, have been examined which though similar in geomagnetic latitude and longitude have very different geographical latitudes. This has allowed the separation of effects due to the season, the daylength and the post midnight collapse. The scale length of the coupling has been estimated and related to the degree to which the spread-F effects appeared to be coupled. It is shown that at times when the conditions are different in the two hemispheres marked differences occur in the spread-F incidence. It is concluded that dominant control of midlatitude spread-F does not involve interhemispheric coupling. This seems to imply that dominant control of midlatitude spread-F is played by irregularities of scales shorter than 2 km and consequently that coupling between the E-and F-regions is also unlikely to be of dominant importance. At times the marked coincidence of spread-F in the two hemispheres makes it appear that when conditions at both ends of the field line are suitable for the initiation of spread-F, coupling takes place. During the decrease in spread-F during the post midnight collapse at Arecibo there is some evidence that the incidence of spread-F increases in the conjugate hemisphere and that this coupling may be related to interhemispheric plasma flow.
BibTeX:
@article{Zinchenko1977,
  author = {G.N Zinchenko and J.S Nisbet},
  title = {Coupling of mid-latitude spread-F between conjugate stations},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1977},
  volume = {39},
  number = {4},
  pages = {469-474},
  url = {http://www.sciencedirect.com/science/article/pii/0021916977901556},
  doi = {10.1016/0021-9169(77)90155-6}
}
Chameides WL and Walker JCG (1976), "A time-dependent photochemical model for ozone near the ground", Journal of Geophysical Research. Vol. 81(3), pp. 413-420.
Abstract: We present a time-dependent photochemical model of tropospheric ozone. In accordance with our previous calculations (Chameides and Walker, 1973) we treat ozone as an active chemical constituent with a local abundance that is determined by photochemical processes rather than by transport processes. The local abundance of odd nitrogen is shown to play a major role in determining the intensity of photochemical production and destruction of ozone, a large local abundance of NOx (= NO + NO2) leading to large diurnal ozone variations. The photochemical model is shown to reproduce the diurnal variations of ozone and nitrogen dioxide observed near the ground at Research Triangle Park in North Carolina.
BibTeX:
@article{Chameides1976,
  author = {Chameides, William L. and Walker, James C. G.},
  title = {A time-dependent photochemical model for ozone near the ground},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {3},
  pages = {413-420},
  url = {http://dx.doi.org/10.1029/JC081i003p00413},
  doi = {10.1029/JC081i003p00413}
}
Cogger L, Vij K and Carlson H (1976), "F-region temperatures from measurements of plasma scale height", Journal of Atmospheric and Terrestrial Physics . Vol. 38(1), pp. 93-96.
Abstract: From incoherent scatter data collected at the Arecibo Observatory from 1965–1968 a comparison was made between measured values of nighttime F-region electron and ion temperature and the plasma temperature inferred from the topside scale height of the measured electron concentration profile. It was found that these temperatures agreed to within a few per cent, implying that the exospheric temperature can be obtained with reasonable accuracy by either method. Caution must be exercised in applying this conclusion to other latitudes and times because of the restrictive conditions required. These conditions are discussed briefly.
BibTeX:
@article{Cogger1976,
  author = {L.L Cogger and K.K Vij and H.C Carlson},
  title = {F-region temperatures from measurements of plasma scale height},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1976},
  volume = {38},
  number = {1},
  pages = {93-96},
  url = {http://www.sciencedirect.com/science/article/pii/0021916976901999},
  doi = {10.1016/0021-9169(76)90199-9}
}
Fejer BG, Farley DT, Balsley BB and Woodman RF (1976), "Radar studies of anomalous velocity reversals in the equatorial ionosphere", Journal of Geophysical Research. Vol. 81(25), pp. 4621-4626.
Abstract: Radar observations made at Jicamarca show that the equatorial electrojet current and the E and F region electric fields can reverse from their normal direction during the day or night and during magnetically quiet or disturbed conditions. The nighttime reversals can only be detected by such radar measurements. The observations support most of the current hypotheses concerning the electrojet plasma instabilities. The rapid reversals sometimes seen during disturbed conditions indicate that high-latitude currents and electric fields associated with substorm activity strongly perturb the dynamo current system at all latitudes.
BibTeX:
@article{Fejer1976,
  author = {Fejer, B. G. and Farley, D. T. and Balsley, B. B. and Woodman, R. F.},
  title = {Radar studies of anomalous velocity reversals in the equatorial ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {25},
  pages = {4621-4626},
  doi = {10.1029/JA081i025p04621}
}
Hagen JB and Behnke RA (1976), "Detection of the electron component of the spectrum in incoherent scatter of radio waves by the ionosphere", Journal of Geophysical Research. Vol. 81(19), pp. 3441-3443.
Abstract: The electron component of the ionospheric incoherent scatter spectrum has been detected at the Arecibo Observatory. The frequency spectra of echoes from heights between 2000 and 5000 km show a broad pedestal extending approximately 1.2 MHz on either side of the narrow ion component. The power and width of the electron component provide a direct measure of the temperature and density of ionospheric electrons.
BibTeX:
@article{Hagen1976,
  author = {Hagen, J. B. and Behnke, R. A.},
  title = {Detection of the electron component of the spectrum in incoherent scatter of radio waves by the ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {19},
  pages = {3441-3443},
  url = {http://dx.doi.org/10.1029/JA081i019p03441},
  doi = {10.1029/JA081i019p03441}
}
Harper RM, Wand RH, Zamlutti CJ and Farley DT (1976), "E region ion drifts and winds from incoherent scatter measurements at Arecibo", Journal of Geophysical Research. Vol. 81(1), pp. 25-35.
Abstract: Ion velocity and temperature measurements at Arecibo for two winter days were analyzed to determine the large-scale dynamical structure of the E region. Southward neutral winds were derived directly from the ion velocity, while the southward electric field was obtained with a reasonable extrapolation of the measured ion-neutral collision frequency. Eastward winds were estimated after assuming a model eastward electric field taken from previous F region measurements at Arecibo. The main results are as follows: (1) Large oscillations in the ion drifts, neutral winds, and temperatures were present on the days of observation. The oscillations possessed a characteristic downward phase progression and dominant periods that were near semidiurnal. (2) Wind and temperature amplitudes were 40-100 m/s and 30°-60°K, respectively. Vertical wavelengths for a semidiurnal period were about 50 km. The calculated southward electric fields are typical of daytime F region values at Arecibo, -1 to -2 mV/m. (3) The observed semidiurnal amplitudes, phases, and vertical wavelengths of the wind and temperature oscillations do not closely match the predictions of classical tidal theory or the theory of Lindzen and Hong which includes dissipation and background winds.
BibTeX:
@article{Harper1976,
  author = {Harper, R. M. and Wand, R. H. and Zamlutti, C. J. and Farley, D. T.},
  title = {E region ion drifts and winds from incoherent scatter measurements at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {1},
  pages = {25-35},
  url = {http://dx.doi.org/10.1029/JA081i001p00025},
  doi = {10.1029/JA081i001p00025}
}
Kim H, Crawford FW and Harker KJ (1976), "Analysis of the backscatter spectrum in an ionospheric modification experiment", Journal of Geophysical Research. Vol. 81(1), pp. 193-198.
Abstract: The purpose of this study is to compare predictions of the backscatter spectrum, including effects of ionospheric inhomogeneity, with experimental observations of incoherent backscatter from an artificially heated region. Our calculations show that the strongest backscatter echo received is not from the reflection level but from a region some distance below (about 900–1100 m for an experiment carried out at Arecibo). By taking the standing wave pattern of the pump properly into account the present theory explains certain asymmetrical features of the upshifted and downshifted plasma lines in the backscatter spectrum.
BibTeX:
@article{Kim1976,
  author = {Kim, H. and Crawford, F. W. and Harker, K. J.},
  title = {Analysis of the backscatter spectrum in an ionospheric modification experiment},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {1},
  pages = {193-198},
  url = {http://dx.doi.org/10.1029/JA081i001p00193},
  doi = {10.1029/JA081i001p00193}
}
Lanzerotti LJ, Maclennan CG and Cogger LL (1976), "Arecibo ionosphere total electron content during nonstorm times", Journal of Geophysical Research. Vol. 81(31), pp. 5573-5577.
Abstract: The occurrences of nighttime ‘ledges’ in the total electron content (TEC) measurements at Arecibo are discussed and related, via a model calculation, to the rise and fall of the height of the peak density (hmax) around local midnight. The model behavior of hmax is consistent with observations and with reported changes in flow directions of the meridional nighttime neutral wind system deduced from incoherent scatter measurements. The results suggest that nighttime TEC data might be used to give indirect evidence for thermospheric wind flow directions.
BibTeX:
@article{Lanzerotti1976,
  author = {Lanzerotti, L. J. and Maclennan, C. G. and Cogger, L. L.},
  title = {Arecibo ionosphere total electron content during nonstorm times},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {31},
  pages = {5573-5577},
  url = {http://dx.doi.org/10.1029/JA081i031p05573},
  doi = {10.1029/JA081i031p05573}
}
Mahajan KK and Saxena OP (1976), "Continuous measurements of nighttime electron concentration profiles and estimation of neutral wind velocities at Arecibo", Journal of Geophysical Research. Vol. 81(19), pp. 3165-3170.
Abstract: Results of continuous measurements of nighttime electron concentration profiles, using short pulses with the Arecibo incoherent scatter radar, are presented. The electron density distribution around the F2 peak is found to be nearly ? Chapman type and has a scale height which is the same as that of the neutral atmosphere. Vertical transport velocities are calculated from the time and the height gradients of the electron concentration, and the meridional neutral wind is deduced from these vertical drifts. The wind velocities are found to be positive most of the night and start decreasing rapidly before midnight. The velocities reach a very low value after about 0100 hours. The average maximum value of the velocity is about 100 m s-1. On the average the equinox values seem to be higher than the summer values. These results are compared with those recently obtained from Doppler shift measurements at Arecibo.
BibTeX:
@article{Mahajan1976,
  author = {Mahajan, K. K. and Saxena, O. P.},
  title = {Continuous measurements of nighttime electron concentration profiles and estimation of neutral wind velocities at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {19},
  pages = {3165-3170},
  url = {http://dx.doi.org/10.1029/JA081i019p03165},
  doi = {10.1029/JA081i019p03165}
}
Mantas GP and Walker JC (1976), "The penetration of soft electrons into the ionosphere", Planetary and Space Science . Vol. 24(5), pp. 409-423.
Abstract: Calculations are presented of energy spectra and angular and spatial distributions of electron fluxes in the ionosphere resulting from precipitation ofmonoenergetic (E = 25, 50 and 100 eV) electrons. The incident electrons are assumed to be isotropic over the downward direction. It is found that the resulting steady-state electron fluxes above ca. 300 km are highly anisotropic, and that the pitch angle distribution is energy dependent. About 15 per cent of the incident electrons are backscattered elastically to the protonosphere. A much larger number of electrons escape after they have deposited a part of their energy in the atmosphere. The mean energy of the escaping electrons is about half that of the incident electrons. About 50% of the incident energy is absorbed in the atmosphere, the remainder being returned to the protonosphere. The rate of absorption of energy is a maximum at heights between 300 and 400 km. Most of the energy is absorbed in ionization and excitation of atomic oxygen. An appreciable amount of energy is, however, absorbed as heat by the ambient electron gas. Altitude profiles are presented of the rates of ionization, excitation, and electron heating caused by soft electron precipitation.
BibTeX:
@article{Mantas1976,
  author = {George P. Mantas and James C.G. Walker},
  title = {The penetration of soft electrons into the ionosphere},
  journal = {Planetary and Space Science },
  year = {1976},
  volume = {24},
  number = {5},
  pages = {409-423},
  url = {http://www.sciencedirect.com/science/article/pii/0032063376900854},
  doi = {10.1016/0032-0633(76)90085-4}
}
Margulis L, Walker JCG and Mitchell R (1976), "Reassessment of roles of oxygen and ultraviolet light in Precambrian evolution", Nature. Vol. 264, pp. 620-624.
Abstract: The rise of atmospheric oxygen occurred long before the sudden appearance of multicellular eukaryotic organisms in the later Precambrian. Oxygen was necessary but not sufficient for the evolution of multicellular eukaryotes: the rise of modern aerobic eukaryotes (fungi, animals and plants) occurred in a fully oxygenic atmosphere only after the evolution in protists of microtubule-utilising processes (mitosis and meiosis).
BibTeX:
@article{Margulis1976,
  author = {Margulis, L. and Walker, J. C. G. and Mitchell, R.},
  title = {Reassessment of roles of oxygen and ultraviolet light in Precambrian evolution},
  journal = {Nature},
  year = {1976},
  volume = {264},
  pages = {620-624},
  url = {http://www.nature.com/nature/journal/v264/n5587/abs/264620a0.html},
  doi = {10.1038/264620a0}
}
Mathews JD (1976), "Measurements of the diurnal tides in the 80- to 100-km altitude range at Arecibo", Journal of Geophysical Research. Vol. 81(25), pp. 4671-4677.
Abstract: The incoherent scatter radar at Arecibo has been used to measure the 80- to 100-km wind system on two November and two April days. The wind system is shown to correspond most closely to the S1,1 mode diurnal tide. Dissipation effects were always important, and in the April data the tide was seen to ‘break’ at an altitude of 92 km and an amplitude of 60 m/s. The observed vertical wavelength was ?z = 19.5 km; a Richardson number of 0.2, a 40°K temperature oscillation, and an upward energy flux of 4.2 â 10?4 W/m² were inferred.
BibTeX:
@article{Mathews1976,
  author = {Mathews, John D.},
  title = {Measurements of the diurnal tides in the 80- to 100-km altitude range at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {25},
  pages = {4671-4677},
  url = {http://dx.doi.org/10.1029/JA081i025p04671},
  doi = {10.1029/JA081i025p04671}
}
Shen JS, Swartz WE, Farley DT and Harper RM (1976), "Ionization layers in the nighttime E region valley above Arecibo", Journal of Geophysical Research. Vol. 81(31), pp. 5517-5526.
Abstract: Incoherent scatter observations of the nighttime E region valley above Arecibo often show ‘intermediate layers’ within this valley. A detailed study of one particular such layer indicates that average production rates within the layer must be of the order of 1–5 cm-3/s (i.e., much higher than estimated levels of scattered Lyman alpha and betha) in order to satisfy the ion continuity equation, unless the percentage of metallic ions within the layer is very high, which is probably not the case. By studying the shape of the layer and its evolution in time it is possible to infer vertical ion drift velocities, which cannot yet be measured directly at night in the E region by using incoherent scatter because of the low signal levels. Using these drift velocities, one can roughly estimate either the north-south or the east-west component of the neutral wind, depending upon the altitude.
BibTeX:
@article{Shen1976,
  author = {Shen, Jenny S. and Swartz, Wesley E. and Farley, Donald T. and Harper, Robert M.},
  title = {Ionization layers in the nighttime E region valley above Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {31},
  pages = {5517-5526},
  url = {http://dx.doi.org/10.1029/JA081i031p05517},
  doi = {10.1029/JA081i031p05517}
}
St.-Maurice JP, Hanson WB and Walker JCG (1976), "Retarding potential analyzer measurement of the effect of ion-neutral collisions on the ion velocity distribution in the auroral ionosphere", Journal of Geophysical Research. Vol. 81(31), pp. 5438-5446.
Abstract: The action of strong dc electric fields at high latitudes combined with a predominance of ion-neutral collisions has for some time been expected to create appreciable departures of the ion velocity distribution from the equilibrium Maxwellian configuration. We present new evidence gathered with the retarding potential analyzer on the AE-C satellite that shows that the ion velocity distribution departs significantly from the Maxwellian shape at ion temperatures greater than 1500°K. From the analysis of more than 50 volt-ampere characteristics we have determined the shape of the ion velocity distribution in the velocity plane perpendicular to the magnetic field direction. Theoretical analysis shows that the use of a relaxation model for the description of ion-neutral collisions gives velocity distributions for both O+ and molecular ions that are qualitatively correct. However, the departures from the Maxwellian configuration are always exaggerated by the theory. An immediate consequence is that the threshold for the onset of the Ott and Farley microinstability caused by the double-hump character of the velocity distribution must be increased to at least 80 mV/m. Finally, if the ion temperature exceeds 2000°K, we find that the interpretation of the retarding potential analyzer data can be seriously affected by the use of the normally assumed Maxwellian ion velocity distribution in the data inversion process. For very strong electric fields, ion temperatures can be underestimated by more than 2000°K, and composition ratios can be affected by more than a factor of 2. Other ground-based or in situ measurements should be similarly affected.
BibTeX:
@article{St.-Maurice1976,
  author = {St.-Maurice, J. -P. and Hanson, W. B. and Walker, J. C. G.},
  title = {Retarding potential analyzer measurement of the effect of ion-neutral collisions on the ion velocity distribution in the auroral ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {31},
  pages = {5438-5446},
  doi = {10.1029/JA081i031p05438}
}
Torr MR, Burnside RG, Hays PB, Stewart AI, Torr DG and Walker JCG (1976), "Metastable 2D atomic nitrogen in the mid-latitude nocturnal ionosphere", Journal of Geophysical Research. Vol. 81(4), pp. 531-537.
Abstract: At night at mid-latitudes the sources of N(²D) in the F region are reduced to the dissociative recombination of NO+. The only important sinks are quenching by atomic oxygen and electrons. As a result, a photochemical study made in the nighttime is greatly simplified in comparison with one made in the daytime. At night, however, the optical emission at 5200 å resulting from the transition from N(²D) to N(4S) is difficult to measure because of the low intensities. By combining ground-based measurements of I 5200 with coincident satellite observations of neutral and ion densities and temperatures and the shape of the 5200 å emission profile, we are able to relate the rate of quenching by atomic oxygen and the efficiency of production of N(²D) to the rate of quenching by electrons. Assuming a rate of 1.0 â 10-9 (Te/300)0.5 cm¨ s-1 for quenching by electrons, we obtain 1.5-2.5 â 10-12 cm¨ s-1 for quenching by atomic oxygen and an efficiency of (0.8-1.0) ± 30% for the production of N(²D) by dissociative recombination of NO+. The recent laboratory determination of the rate coefficient for the recombination of NO+ of 4.3 â 10-7(Te/300)-0.37 cm¨ s-1 is found to be in good agreement with the measured ion densities.
BibTeX:
@article{Torr1976,
  author = {Torr, M. R. and Burnside, R. G. and Hays, P. B. and Stewart, A. I. and Torr, D. G. and Walker, J. C. G.},
  title = {Metastable 2D atomic nitrogen in the mid-latitude nocturnal ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1976},
  volume = {81},
  number = {4},
  pages = {531-537},
  doi = {10.1029/JA081i004p00531}
}
Torr DG, Torr MR, Rusch DW, Hays PB, Mauersberger K, Walker JCG, Spencer NW, Hedin AE, Brinton HC and Theis RF (1976), "Atomic nitrogen densities in the thermosphere", Geophysical Research Letters. Vol. 3(1), pp. 1-4.
Abstract: Recently atomic nitrogen densities of 106cm-3 were measured at 400 km by the open source mass spectrometer on the Atmosphere Explorer-C satellite (AE-C). Daytime N densities 5 â 107cm-3 at 160 km have also been inferred from airglow and other measurements on AE-C. We show that atomic nitrogen densities of this magnitude result in significantly lower values for the O2+ concentration than those measured on AE-C over the altitude range to 160 to 200 km, because of the removal process O2+ + N k3 -- NO+ + O. We show that the discrepancy can be explained in terms of latitudinal variations in both the N and O2 densities. We also present evidence which indicates that k3 could be as low as 1 â 10-10cm-3 at ionospheric temperatures.
BibTeX:
@article{Torr1976a,
  author = {Torr, D. G. and Torr, M. R. and Rusch, D. W. and Hays, P. B. and Mauersberger, K. and Walker, J. C. G. and Spencer, N. W. and Hedin, A. E. and Brinton, H. C. and Theis, R. F.},
  title = {Atomic nitrogen densities in the thermosphere},
  journal = {Geophysical Research Letters},
  year = {1976},
  volume = {3},
  number = {1},
  pages = {1-4},
  url = {http://dx.doi.org/10.1029/GL003i001p00001},
  doi = {10.1029/GL003i001p00001}
}
Vickrey JF, Swartz WE and Farley DT (1976), "Incoherent scatter measurements of ion counterstreaming", Geophysical Research Letters. Vol. 3(4), pp. 217-220.
Abstract: The large mass differences between the ions present in the transition region between the F layer and protonosphere can cause individual ion species to drift at different velocities during periods of rapid temperature change. Calculations show that these velocity differences can be detected using incoherent scatter. Preliminary observations indicate that velocity differences between H+ and O+ can be as large as 80 m/s after sunset. Such simultaneous measurements of the fluxes of individual ion species are essential for detailed studies of the charge exchange reactions between H+ and O+ and of the morphology of ionospheric-protonospheric coupling.
BibTeX:
@article{Vickrey1976,
  author = {Vickrey, James F. and Swartz, Wesley E. and Farley, Donald T.},
  title = {Incoherent scatter measurements of ion counterstreaming},
  journal = {Geophysical Research Letters},
  year = {1976},
  volume = {3},
  number = {4},
  pages = {217-220},
  url = {http://dx.doi.org/10.1029/GL003i004p00217},
  doi = {10.1029/GL003i004p00217}
}
Wand RH (1976), "Semidiurnal tide in the E region from incoherent scatter measurements at Arecibo", Radio Science. Vol. 11(7), pp. 641-652.
Abstract: A five-pulse technique was implemented for the 430 MHz incoherent scatter radar at Arecibo Observatory (18.3°N), to explore the detailed thermal structure of the E region from 105 to 130 km with an altitude resolution of 3 km. Five days of measurements in Sept–Oct 1970 showed long-period temperature fluctuations having a downward phase progression. The temperature oscillations are interpreted as manifestations of a semidiurnal tide which is quite stable over a 12-day period, together with a superimposed spectrum of shorter-period gravity waves which are randomly phased from day to day. The semidiurnal tide increased to a maximum amplitude of 17% of the mean temperature near 115 km and decreased above this altitude as dissipative effects became important. The vertical wavelength, deduced from the altitude variation of semidiurnal tidal phase, showed a smooth increase from about 20 km at an altitude of 109 km to about 50 km at an altitude of 127 km. No ready interpretation of the observed tidal characteristics was possible in terms of present theories for the semidiurnal tide. Altitude profiles of mean daytime temperature and ion-neutral collision frequency were also obtained from the measurements. The mean temperature gradient between 115 and 130 km was 15 K/km, which is somewhat larger than that given by current atmospheric models.
BibTeX:
@article{Wand1976,
  author = {Wand, R. H.},
  title = {Semidiurnal tide in the E region from incoherent scatter measurements at Arecibo},
  journal = {Radio Science},
  year = {1976},
  volume = {11},
  number = {7},
  pages = {641-652},
  url = {http://dx.doi.org/10.1029/RS011i007p00641},
  doi = {10.1029/RS011i007p00641}
}
Behnke RA and Vickrey JF (1975), "Radar evidence of Fe+ in a sporadic-E layer", Radio Science. Vol. 10(3), pp. 325-327.
Abstract: Incoherent scatter results are presented using compressed-pulse techniques to study a sporadic-E layer at Arecibo. Multiple Barker-coded pulses were used to obtain the autocorrelation function of the Es layer. A 13-bit code with a baud length of 4 usec was employed, resulting in 600-m height resolution. The observations are examined for the presence of Fe+ by least-square fitting the measured autocorrelation functions to a library of theoretical ones. The analysis indicates that Fe+ dominates in the Es layer, usually providing about 70% of the ionization.
BibTeX:
@article{Behnke1975,
  author = {Behnke, Richard A. and Vickrey, James F.},
  title = {Radar evidence of Fe+ in a sporadic-E layer},
  journal = {Radio Science},
  year = {1975},
  volume = {10},
  number = {3},
  pages = {325-327},
  url = {http://dx.doi.org/10.1029/RS010i003p00325},
  doi = {10.1029/RS010i003p00325}
}
Chameides WL and Walker JCW (1975), "Stratospheric Ozone: The Possible Effects of Tropospheric-Stratospheric Feedback", Science. Vol. 190, pp. 1294-1295.
BibTeX:
@article{Chameides1975,
  author = {Chameides, W. L. and Walker, J. C. W.},
  title = {Stratospheric Ozone: The Possible Effects of Tropospheric-Stratospheric Feedback},
  journal = {Science},
  year = {1975},
  volume = {190},
  pages = {1294-1295},
  url = {http://www.sciencemag.org/content/190/4221/1294},
  doi = {10.1126/science.190.4221.1294}
}
Cunnold DM (1975), "Vertical Transport Coefficients in the Mesosphere Obtained from Radar Observations", Journal of the Atmospheric Sciences. Vol. 32, pp. 2191-2200.
Abstract: Incoherent scatter echoes from the mesosphere are interpreted in terms of isolated layers of mesospheric turbulence in the manner of Woodman and Guillen. The parameters describing such turbulent layers are evaluated and shown to be consistent with observations and calculations of eddy mixing and dissipation in the mesosphere, and vertical mixing by this process may make a substantial contribution to vertical mixing in this region of the atmosphere. Thew turbulent layers should have also produced partial reflections of a magnitude similar to those typically observed with that technique. It is thus suggested that incoherent scatter returns and partial reflections be used to evaluate the contribution of turbulent layers to eddy mixing in the mesosphere. An expression for the resulting time-averaged diffusion coefficient at mesospheric heights is presented as a function of the received power and correlation time obtained from incoherent scatter observations.
BibTeX:
@article{Cunnold1975,
  author = {D. M. Cunnold},
  title = {Vertical Transport Coefficients in the Mesosphere Obtained from Radar Observations},
  journal = {Journal of the Atmospheric Sciences},
  year = {1975},
  volume = {32},
  pages = {2191-2200},
  url = {http://dx.doi.org/10.1175/1520-0469(1975)032<2191:VTCITM>2.0.CO;2}
}
Harper RM, Wand RH and Whitehead JD (1975), "Comparison of Arecibo E-region data and sporadic-E theory: a measurement of the diffusion coefficient", Radio Science. Vol. 10(3), pp. 357-361.
Abstract: Incoherent scatter measurements using multiple-pulse techniques were performed at Arecibo to study the E region with a height resolution of 2.4 km. These simultaneous measurements of ion temperature, ion-neutral collision frequency, and electron density, as well as horizontal and vertical components of ion drift velocity, have allowed comparison between theories of sporadic-E and experiment. Sporadic-E layers were consistently observed to descend along the curve where the vertical ion drift velocity (Vz) was zero and its gradient dVz/dz was negative, as predicted by redistribution theory. Assuming no diffusion, the calculated effective recombination coefficient at the layer peak is more than an order of magnitude too small for NO+ or O2+, and varies with height in a manner which is unacceptable for a recombination coefficient. This indicates that the layer is composed of long-lived ions (probably metallic), and that the peak layer density is controlled by diffusion rather than recombination. By ignoring recombination, the diffusion coefficient was estimated from the layer thickness and the vertical gradient in the vertical ion velocity. The results were compared with independent values calculated from the measurements of ion temperature and ion-neutral collision frequency. The two estimates were in good agreement over the range 110 to 120 km, showing that electron densities in sporadic-E layers are primarily determined by molecular diffusion.
BibTeX:
@article{Harper1975,
  author = {Harper, R. M. and Wand, R. H. and Whitehead, J. D.},
  title = {Comparison of Arecibo E-region data and sporadic-E theory: a measurement of the diffusion coefficient},
  journal = {Radio Science},
  year = {1975},
  volume = {10},
  number = {3},
  pages = {357-361},
  url = {http://dx.doi.org/10.1029/RS010i003p00357},
  doi = {10.1029/RS010i003p00357}
}
Ho M and Moorcroft D (1975), "Composition and temperatures of the topside ionosphere over Arecibo ", Planetary and Space Science . Vol. 23(2), pp. 315 - 322.
Abstract: Results of analysis of about 150 autocorrelation functions are presented for the period from about 2300 hr on 5 October to about 1200 hr on 7 October 1967. A large percentage concentration of helium ions are observed. It reaches a value as high as 50 per cent with a maximum at around 800 km. Downward heat fluxes deduced from the temperature variations yield a value of about 2–2.5 â 109 eV cm?2 sec?1 during the period 1200–1600 hr and a value of about 1.5 â 108 eV cm?2 sec?1 during the period 0100–0400 hr at night. These agree well with other measurements. The O+ ions are found not to be in diffusive equilibrium, and from the O+ fluxes and the electron density profiles, the O+ drift velocity has been estimated. It is found that the speed can be as high as 1–5 â 103 cm sec?1 even at altitudes as high as 700 km.
BibTeX:
@article{Ho1975315,
  author = {M.C. Ho and D.R. Moorcroft},
  title = {Composition and temperatures of the topside ionosphere over Arecibo },
  journal = {Planetary and Space Science },
  year = {1975},
  volume = {23},
  number = {2},
  pages = {315 - 322},
  url = {http://www.sciencedirect.com/science/article/pii/0032063375901373},
  doi = {10.1016/0032-0633(75)90137-3}
}
Lee M and Nisbet J (1975), "Propagation Predictions and Studies Using a Ray Tracing Program Combined with a Theoretical Ionospheric Model", IEEE Transactions of Antennas and Propagation. Vol. 23(1), pp. 132 - 136.
Abstract: Radio wave propagation predictions are described in which modern comprehensive theoretical ionospheric models are coupled with ray-tracing programs. In the computer code described, a network of electron density and collision frequency parameters along a band about the great circle path is calculated by specifying the transmitter and receiver geographic coordinates, time, the day number, and the 2800-MHz solar flux. The ray paths are calculated on specifying the frequency, mode, range of elevation angles, and range of azimuth angles from the great circle direction. The current program uses a combination of the Penn State MKIEandFregion models and the Mitra-RoweDandEregion model. Application of the technique to the prediction of satellite to ground propagation and calculation of oblique incidence propagation paths and absorption are described. The implications of the study to the development of the next generation of ionospheric models are discussed.
BibTeX:
@article{Lee1975,
  author = {Myung Lee and Nisbet, J. },
  title = {Propagation Predictions and Studies Using a Ray Tracing Program Combined with a Theoretical Ionospheric Model},
  journal = {IEEE Transactions of Antennas and Propagation},
  year = {1975},
  volume = {23},
  number = {1},
  pages = {132 - 136},
  doi = {10.1109/TAP.1975.1141018}
}
Newton GP and Walker JCG (1975), "Electron density decrease in SAR arcs resulting from vibrationally excited nitrogen", Journal of Geophysical Research. Vol. 80(10), pp. 1325-1327.
Abstract: Enhanced vibration of molecular nitrogen is produced in SAR arcs by collisions with hot thermal electrons. The rate coefficient for the reaction between oxygen ions and molecular nitrogen is increased as a result of the vibrational excitation, and this leads to an increase in the rate of loss of F region ionization. By solving the F region continuity equation for conditions appropriate to SAR arcs both with and without allowance for the effects of vibrational excitation we show that vibrational excitation may be the cause of the F region electron density depression that is observed in SAR arcs. Our solutions also show that the observed depression cannot be caused by redistribution of ionization due to enhanced electron temperatures alone.
BibTeX:
@article{Newton1975,
  author = {Newton, George P. and Walker, James C. G.},
  title = {Electron density decrease in SAR arcs resulting from vibrationally excited nitrogen},
  journal = {Journal of Geophysical Research},
  year = {1975},
  volume = {80},
  number = {10},
  pages = {1325-1327},
  url = {http://dx.doi.org/10.1029/JA080i010p01325},
  doi = {10.1029/JA080i010p01325}
}
Sobral J, Carlson H and Farley D (1975), "Airglow studies of the nighttime dynamics of the ionosphere near Arecibo", Instituto de Pesquisas Espaciais, Sao Jose dos Campos (internal publication). Vol. n/a-n/a, pp. n/a-n/a.
BibTeX:
@article{Sobral1975,
  author = {Sobral, JHA and Carlson, HC and Farley, DT},
  title = {Airglow studies of the nighttime dynamics of the ionosphere near Arecibo},
  journal = {Instituto de Pesquisas Espaciais, Sao Jose dos Campos (internal publication)},
  year = {1975},
  volume = {n/a-n/a},
  pages = {n/a-n/a},
  doi = {sid.inpe.br/iris@1905/2005/07.25.20.53.38-0}
}
Torr MR, Torr D, Hoffman R, Hanson W, Hoffman J, Peterson W and Walker J (1975), "An auroral F-region study using in situ measurements by the Atmosphere Explorer-C satellite", Planetary and Space Science . Vol. 23(12), pp. 1669-1679.
Abstract: On 14 July 1974 the Atmosphere Explorer-C satellite flew through an aurora at F-region altitudes just after local midnight. The effects of the particle influx are clearly evident in the ion densities, the 6300 å airglow, and the electron and ion temperatures. This event provided an opportunity to study the agreement between the observed ion densities and those calculated from photochemical theory using in situ measurements of such atmospheric parameters as the neutral densities and the differential electron energy spectra obtained along the satellite track. Good agreement is obtained for the ions O2+, NO+ and N2+ using photochemical theory and measured rate constants and electron impact cross sections. Atomic nitrogen densities are calculated from the observed [NO+]/[O2+] ratio. In the region of most intense electron fluxes (20 erg cm-2 sec-1) at ~280 km, the N density is found to be between 2 and 7 â 107 cm-3. The resulting N densities are found to account for approx. 60% of the production of N+ through electron impact on N and the resonant charge exchange of O+(2P) with N(+S). This reaction also provides a significant source of O(1S) in the aurora at F-region altitudes. In the region of intense fast electron influx, the reaction with atomic nitrogen is found to be the main loss of O+(2P).
BibTeX:
@article{Torr1975,
  author = {Marsha R. Torr and D.G. Torr and R.A. Hoffman and W.B. Hanson and J.H. Hoffman and W.K. Peterson and J.C.G. Walker},
  title = {An auroral F-region study using in situ measurements by the Atmosphere Explorer-C satellite},
  journal = {Planetary and Space Science },
  year = {1975},
  volume = {23},
  number = {12},
  pages = {1669-1679},
  url = {http://www.sciencedirect.com/science/article/pii/003206337590094X},
  doi = {10.1016/0032-0633(75)90094-X}
}
Torr D, Torr MR, Walker JC and Hoffman R (1975), "Particle precipitation in the south atlantic geomagnetic anomaly", Planetary and Space Science . Vol. 23(1), pp. 15-26.
Abstract: A simple model of the motion of charged particles in the closed field line magnetic field for L<= 4·5 is used together with Injun 3 measurements of 40 keV precipitated electrons made in the northern hemisphere to estimate theoretically the extent of electron precipitation, the energy input and the 3914 å airglow in the South Atlantic geomagnetic anomaly. Using average values of the northern hemisphere precipitated electron flux, two regions of significantly enhanced electron precipitation are found in the southern hemisphere. One occurs in the region 10-20°E and 40-50°S, with L~ 2, and the second near 30°E and 65°S, with L ~4.5. Approximately 0.04 erg cm-2 sec-1 are deposited by 40 keV electrons for 50 per cent of the time in the first region and half that amount in the second. This increases to~0·1 and 0·02 erg cm-2 sec-1 respectively for 15 per cent of the time for near sunspot minimum conditions. The results show a gradual increase in precipitation on the western side of the anomaly followed by a rapid increase and sudden cut-off in precipitation within a few degrees west of minimum B. The flux on L = 2 reaches a “spike” in the southern hemisphere ~f35 times greater than the average flux precipitated on L = 2 in the northern hemisphere. This increase in precipitation arises from the loss of “trapped” particles to the atmosphere where the mirror heights are lowest.
BibTeX:
@article{Torr1975a,
  author = {D.G. Torr and Marsha R. Torr and James C.G. Walker and R.A. Hoffman},
  title = {Particle precipitation in the south atlantic geomagnetic anomaly},
  journal = {Planetary and Space Science },
  year = {1975},
  volume = {23},
  number = {1},
  pages = {15-26},
  url = {http://www.sciencedirect.com/science/article/pii/0032063375900641},
  doi = {10.1016/0032-0633(75)90064-1}
}
Utlaut W (1975), "Ionospheric modification induced by high-power HF transmitters- A potential for extended range VHF-UHF communications and plasma physics research", IEEE Proceedings. Vol. 63(7), pp. 1022-1043.
Abstract: When the ionized upper atmosphere of the earth is illuminated by high-power HF radio waves at appropriate frequencies, the temperature of electrons in the ionosphere can be raised substantially. In addition, radio waves with sufficient energy cause parametric instabilities that generate a spectrum of intense plasma waves. Observations of these phenomena have produced new understanding of plasma processes. One consequence of heating and plasma wave generation is that irregularities are formed in the electron distribution which are aligned with the earth's magnetic field. Because of this, a scatterer of large radar cross section is produced, which scatters HF through UHF communication signals over long distance paths, that would not otherwise be normally possible by ionospheric means. This paper summarizes results of radio, radar, communication, and photometric experiments that explored the characteristics of the volume of ionosphere which has been intentionally modified, temporarily, above facilities near Boulder (Platteville), Colo., and at Arecibo, Puerto Rico.
BibTeX:
@article{Utlaut1975,
  author = {Utlaut, W.F.},
  title = {Ionospheric modification induced by high-power HF transmitters- A potential for extended range VHF-UHF communications and plasma physics research},
  journal = {IEEE Proceedings},
  year = {1975},
  volume = {63},
  number = {7},
  pages = {1022-1043},
  url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1451809},
  doi = {10.1109/PROC.1975.9879}
}
Walker JCG, Torr DG, Hays PB, Rusch DW, Docken K, Victor G and Oppenheimer M (1975), "Metastable 2P oxygen ions in the daytime thermosphere", Journal of Geophysical Research. Vol. 80(7), pp. 1026-1029.
Abstract: Dayglow radiation at 7319 å has been measured by the visible airglow experiment on Atmosphere Explorer C. The overhead surface brightness measured at 15.4 hours local solar time on January 27, 1974, was 250 ± 10 R. The volume emission rate had a peak value of 20 photons cm-3 s-1 at a height of about 210 km. The data show clear evidence of quenching by collisions with thermal electrons at the higher altitudes and with neutral particles at lower altitudes. Quenching by neutral particles occurs at nearly the gas kinetic rate.
BibTeX:
@article{Walker1975,
  author = {Walker, J. C. G. and Torr, D. G. and Hays, P. B. and Rusch, D. W. and Docken, K. and Victor, G. and Oppenheimer, M.},
  title = {Metastable 2P oxygen ions in the daytime thermosphere},
  journal = {Journal of Geophysical Research},
  year = {1975},
  volume = {80},
  number = {7},
  pages = {1026-1029},
  doi = {10.1029/JA080i007p01026}
}
Weinstock J (1975), "Theory of enhanced airglow during ionospheric modifications", Journal of Geophysical Research. Vol. 80(31), pp. 4331-4345.
Abstract: A calculation is made of the acceleration of electrons during ionospheric modification experiments. The electrons are accelerated by Langmuir waves excited unstable by the parametric instability. It is emphasized that accelerations by Langmuir waves mainly take place at the bottom of the heated region, where the Langmuir waves are slowest and, consequently, the wave-particle interactions are strongest. The velocity distribution F of accelerated electrons is determined by a kinetic equation in which the effects of Langmuir wave turbulence are described by a stochastic wave diffusion tensor. Both resonant and resonant broadened wave-particle interactions, as well as the angular distribution of Langmuir waves, are important. The accelerated electrons are lost by convecting out of the modified region of the ionosphere. A steady state ensues when the production of accelerated electrons by turbulent diffusion is balanced by convective loss. The calculated steady state F is almost flat for a velocity range extending from 4ue to 8ue, with a few electrons accelerated to 10ue. The predicted maximum flux of accelerated electrons is about 2 x 1e9 el cm-2 s-1 for conditions over Platteville, which is sufficient to account for the observed red line enhancements and the green line enhancements as well. The predicted flux for conditions over Arecibo is about 1/8 that for conditions over Platteville. Such a difference has been observed. The model also predicts that the accelerated electrons absorb between 10 and 30% of the transmitter power, depending on the ratio of transmitter power to the threshold power of the parametric instability near the bottom of the modified region.
BibTeX:
@article{Weinstock1975,
  author = {Weinstock, Jerome},
  title = {Theory of enhanced airglow during ionospheric modifications},
  journal = {Journal of Geophysical Research},
  year = {1975},
  volume = {80},
  number = {31},
  pages = {4331-4345},
  url = {http://dx.doi.org/10.1029/JA080i031p04331},
  doi = {10.1029/JA080i031p04331}
}
Zamlutti C (1975), "Atmospheric wave observations at Arecibo ", Journal of Atmospheric and Terrestrial Physics . Vol. 37(4), pp. 625-633.
Abstract: Multiple pulse incoherent scatter experiments, observing E-region altitudes with height resolution better than 2.4 km, have been carried out at Arecibo from August 1972 to January 1973. Neutral temperature, ion-neutral collision frequency and drift velocities were obtained. The results showed an oscillatory behavior of the neutral atmosphere. Evidences of non-linearities of the atmospheric oscillations are explored. They help to determine the period of the tidal mode consistent with the semi-diurnal tide predicted by the theory.
BibTeX:
@article{Zamlutti1975,
  author = {C.J Zamlutti},
  title = {Atmospheric wave observations at Arecibo },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1975},
  volume = {37},
  number = {4},
  pages = {625-633},
  url = {http://www.sciencedirect.com/science/article/pii/0021916975900574},
  doi = {10.1016/0021-9169(75)90057-4}
}
Zamlutti CJ and Farley DT (1975), "Incoherent scatter multiple-pulse measurements at Arecibo", Radio Science. Vol. 10(5), pp. 573-580.
Abstract: The important points governing the design of a multiple-pulse measurement of the incoherent scatter autocorrelation function in the E region are discussed. Since the requirements for good signal-to-noise ratio and good resolution are contradictory, compromises must be made. These considerations dictated the choice of two multiple-pulse schemes which are now being used at the National Astronomy and Ionosphere Center in Arecibo, Puerto Rico. These schemes, one involving five pulses and one involving seven, are described and a few typical examples of the results obtained are presented. The data show that it is now practical during the day, or at night in reasonably strong sporadic-E layers, to make accurate measurements of the complex autocorrelation function in the E region with an altitude resolution of the order of 1 to 3 km in a time of less than 10 min. The number of heights which can be studied simultaneously is limited only by computer capabilities. In the measurements reported here ten altitudes were sampled.
BibTeX:
@article{Zamlutti1975a,
  author = {Zamlutti, Carlos Jose and Farley, D. T.},
  title = {Incoherent scatter multiple-pulse measurements at Arecibo},
  journal = {Radio Science},
  year = {1975},
  volume = {10},
  number = {5},
  pages = {573-580},
  url = {http://dx.doi.org/10.1029/RS010i005p00573},
  doi = {10.1029/RS010i005p00573}
}
Almeida O (1974), "Protonospheric columnar electron contentdetermination-II. Observations", Journal of Atmospheric and Terrestrial Physics . Vol. 36(2), pp. 305-313.
BibTeX:
@article{Almeida1974,
  author = {O.G Almeida},
  title = {Protonospheric columnar electron contentdetermination-II. Observations},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1974},
  volume = {36},
  number = {2},
  pages = {305-313},
  doi = {10.1016/0021-9169(74)90049-X}
}
Arnush D, Fried BD and Kennel CF (1974), "Parametric amplification of propagating electron plasma waves in the ionosphere", Journal of Geophysical Research. Vol. 79(13), pp. 1885-1893.
Abstract: We compute the linear parametric convective amplification of electron plasma waves by an O mode pump propagating vertically into a vertically stratified ionosphere. The upshifted plasma line compares favorably with Arecibo observations, center frequency, spectral width, and possibly amplitude when the radar is aimed in a northerly direction. The dependence of the computed enhanced plasma line shape upon density scale length, electron-to-ion temperature ratio, pump power, density gradient scale length, and backscatter radar incidence angle is investigated.
BibTeX:
@article{Arnush1974,
  author = {Arnush, D. and Fried, B. D. and Kennel, C. F.},
  title = {Parametric amplification of propagating electron plasma waves in the ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1974},
  volume = {79},
  number = {13},
  pages = {1885-1893},
  url = {http://dx.doi.org/10.1029/JA079i013p01885},
  doi = {10.1029/JA079i013p01885}
}
Behnke RA and Kohl H (1974), "The effects of neutral winds and electric fields on the ionospheric F2-layer over Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 36, pp. 325-333.
BibTeX:
@article{Behnke1974,
  author = {Behnke, R A and Kohl, H},
  title = {The effects of neutral winds and electric fields on the ionospheric F2-layer over Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1974},
  volume = {36},
  pages = {325-333},
  doi = {10.1016/0021-9169(74)90051-8}
}
Behnke RA and Hagfors T (1974), "Evidence for the existence of nighttime F-region polarization fields at Arecibo", Radio Science. Vol. 9(2), pp. 211-216.
Abstract: Recent measurements are presented of F-region ion drifts made at Arecibo using a new continuous beamswinging technique. The measurements are applied to the question of the origin of the F-region electric field over Arecibo. It is shown that the daytime electric fields are probably caused by E-region tidal winds, while the nighttime electric fields appear to be generated in the F region itself by thermospheric winds.
BibTeX:
@article{Behnke1974a,
  author = {Behnke, R. A. and Hagfors, T.},
  title = {Evidence for the existence of nighttime F-region polarization fields at Arecibo},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {2},
  pages = {211-216},
  url = {http://dx.doi.org/10.1029/RS009i002p00211},
  doi = {10.1029/RS009i002p00211}
}
Cicerone RJ (1974), "Photoelectrons in the ionosphere: Radar measurements and theoretical computations", Reviews of Geophysics. Vol. 12(2), pp. 259-271.
Abstract: Ionospheric photoelectrons may be studied by measuring the power returned in the plasma lines of the radar incoherent scatter spectrum. This paper reviews the type and quality of information about photoelectrons available from radar measurements. Distinctive capabilities and limitations of this ground-based technique are discussed, and results are presented for a number of plasma line studies, mostly at Arecibo, Puerto Rico, and Millstone Hill, Massachusetts. These results are compared with measurements by satellite-borne instruments and certain findings of theoretical studies of photoelectrons. It is noted that measured photoelectron escape fluxes generally exceed those predicted by current theories and that inadequate input data for theoretical computations are the likely cause of the discrepancy. Other outstanding problems involving photoelectrons require further research and are described here. One of these is the quantitative evaluation of photoelectron transport and energy degradation in the plasma contained in the magnetospheric field tubes. Experimental and theoretical work is needed on this problem to achieve quantitative understanding of protonospheric thermal structure and of predawn temperature and airglow enhancements in the F region of the ionosphere.
BibTeX:
@article{Cicerone1974,
  author = {Cicerone, Ralph J.},
  title = {Photoelectrons in the ionosphere: Radar measurements and theoretical computations},
  journal = {Reviews of Geophysics},
  year = {1974},
  volume = {12},
  number = {2},
  pages = {259-271},
  url = {http://dx.doi.org/10.1029/RG012i002p00259},
  doi = {10.1029/RG012i002p00259}
}
Gordon WE and Carlson HC (1974), "Arecibo heating experiments", Radio Science. Vol. 9(11), pp. 1041-1047.
Abstract: Enhancements of various features of the incoherent scatter spectrum are observed when the ionosphere is illuminated with powerful, high frequency radio waves. The radio waves excite plasma instabilities producing lines or more complex spectral features near the local plasma frequency, at the local ion acoustic frequency, near the local gyrofrequency, and near twice the gyrofrequency. The enhancements occur in a thin slab as observed by the incoherent scatter radar and at both upshifted and downshifted frequencies with respect to the probing radar frequency. The enhancements are observed to vary with time when the excitation is held constant and is turned on or off.The high power radio waves are produced by a 160 kw transmitter feeding a log-periodic pair of curtains mounted at the focus of the 1000-ft reflector and covering the frequency range from 5 to 12 MHz. The effects are observed with the incoherent scatter radar using the same reflector and with ionosondes and photometers.The frequencies of the enhanced plasma line and the ion line and their relation to the pump (high frequency radio wave) frequency are predictable from available parametric instability theory. Other spectral features are being explained as the theory develops with the help of the observations. There remain some discrepancies, in particular the asymmetries in intensity, width, and fluctuations of the upshifted compared to the downshifted plasma lines.
BibTeX:
@article{Gordon1974,
  author = {Gordon, W. E. and Carlson, H. C.},
  title = {Arecibo heating experiments},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {11},
  pages = {1041-1047},
  url = {http://dx.doi.org/10.1029/RS009i011p01041},
  doi = {10.1029/RS009i011p01041}
}
Hagen JB and Hsu PY-S (1974), "The structure of the protonosphere above Arecibo", Journal of Geophysical Research. Vol. 79(28), pp. 4269-4275.
Abstract: Preliminary results are presented from protonospheric observations made with the considerably increased system capability at Arecibo. The least squares technique for interpreting the experimental autocorrelation functions is discussed together with various assumptions that must be made to deduce physical parameters from the data successfully. Typical data show steadily increasing temperatures both day and night up to 2000 km. Composition data agree with diffusive equilibrium models, although for the daytime data, thermal diffusion and flux drag terms are important.
BibTeX:
@article{Hagen1974,
  author = {Hagen, Jon B. and Hsu, Peter You-Sen},
  title = {The structure of the protonosphere above Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1974},
  volume = {79},
  number = {28},
  pages = {4269-4275},
  url = {http://dx.doi.org/10.1029/JA079i028p04269},
  doi = {10.1029/JA079i028p04269}
}
Hagfors T and Behnke RA (1974), "Measurement of three-dimensional plasma velocities at the Arecibo Observatory", Radio Science. Vol. 9(2), pp. 89-93.
Abstract: An observation scheme is described in which it is possible to measure the three velocity components of plasma drift in the ionosphere by using a single monostatic incoherent scatter facility with a steerable antenna. The scheme involves a least-mean-squares fitting of the line-of-sight velocity observed in several different directions to what one would compute from a given set of three orthogonal velocity components. The method is applied to data gathered at the Arecibo Observatory and is shown to be capable of providing velocity information with rms errors of better than 10 m sec-1 for all three components with a time resolution of 20 min.
BibTeX:
@article{Hagfors1974,
  author = {Hagfors, T. and Behnke, R. A.},
  title = {Measurement of three-dimensional plasma velocities at the Arecibo Observatory},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {2},
  pages = {89-93},
  url = {http://dx.doi.org/10.1029/RS009i002p00089},
  doi = {10.1029/RS009i002p00089}
}
Ioannidis G and Farley DT (1974), "High resolution D-region measurements at Arecibo", Radio Science. Vol. 9(2), pp. 151-157.
Abstract: D-region electron densities have been measured with a height resolution of less than 1 km using the incoherent scatter technique with coded pulses. Using a theoretical production model and the measured densities, recombination coefficients were computed for the altitude range from 80 to 95 km. The effective recombination coefficient decreases across the D-region ledge from a value of about 2 â 10?5 cm3 sec?1 below the ledge to a value of the order of 1 to 5 â 10?7 above. The change is presumably due to a transition from water cluster ions to the molecular ions NO+ and O2+.
BibTeX:
@article{Ioannidis1974,
  author = {Ioannidis, G. and Farley, D. T.},
  title = {High resolution D-region measurements at Arecibo},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {2},
  pages = {151-157},
  url = {http://dx.doi.org/10.1029/RS009i002p00151},
  doi = {10.1029/RS009i002p00151}
}
Kantor IJ (1974), "High frequency induced enhancements of the incoherent scatter spectrum at Arecibo, 2", Journal of Geophysical Research. Vol. 79(1), pp. 199-208.
Abstract: When the ionospheric F region is illuminated with a strong O mode HF radio wave, excitations of longitudinal plasma and acoustic waves are observed by 430-MHz radar scattering. The frequency structure of the excited waves and their variability with local parameters, time, and space are described. The observations are interpreted in terms of parametric instability theory. The spectra of the observed features and the correlation of their amplitudes are shown. The upshifted and downshifted plasma lines exhibit some marked asymmetries. Absolute as well as relative amplitudes of the enhancement are presented.
BibTeX:
@article{Kantor1974,
  author = {Kantor, Ivan J.},
  title = {High frequency induced enhancements of the incoherent scatter spectrum at Arecibo, 2},
  journal = {Journal of Geophysical Research},
  year = {1974},
  volume = {79},
  number = {1},
  pages = {199-208},
  url = {http://dx.doi.org/10.1029/JA079i001p00199},
  doi = {10.1029/JA079i001p00199}
}
Muldrew DB and Gonfalone A (1974), "Resonance cone and Bernstein wave interference patterns in a magnetoplasma", Radio Science. Vol. 9(10), pp. 873-880.
Abstract: General dispersion relations for a hot magnetoplasma are used to explain the interference observed between electrostatic waves and the electromagnetic field in an afterglow plasma. Observations are made near both oblique resonance cones (connected with whistler and Z-propagation modes) and in the frequency region corresponding to “Bernstein” waves. Independent measurements of the lower (whistler) and upper (Z-mode) resonance cones, for a particular case, lead to the same isotropic temperature in the late afterglow, namely 540 K. Independent measurements of the lower resonance cone and of Bernstein waves in the early afterglow also lead to consistent isotropic temperatures. As the real and imaginary components of the wave number increase, a point of inflection is reached on the various dispersion curves for homogeneous plane waves beyond which these curves can no longer be used to explain the observed interference fringes. For homogeneous waves with a wave number smaller than that corresponding to the inflection point, reasonable values of Landau damping are obtained which agree roughly with observed damping.
BibTeX:
@article{Muldrew1974,
  author = {Muldrew, D. B. and Gonfalone, A.},
  title = {Resonance cone and Bernstein wave interference patterns in a magnetoplasma},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {10},
  pages = {873-880},
  url = {http://dx.doi.org/10.1029/RS009i010p00873},
  doi = {10.1029/RS009i010p00873}
}
Perkins FW, Oberman C and Valeo EJ (1974), "Parametric instabilities and ionospheric modification", Journal of Geophysical Research. Vol. 79(10), pp. 1478-1496.
Abstract: Parametric instabilities, excited in the ionosphere by high-power HF transmitters with a frequency below the maximum ionospheric plasma frequency, produce nonlinear energy absorption and enhanced scattering of electromagnetic radiation, which has been detected by the Arecibo Thomson scatter radar. This paper reviews and extends both the linear and nonlinear saturation theory of parametric instabilities within the ionospheric context. The new elements are a modification of the emission term to include the effects of nonlinear plasma waves and a numerical integration of the wave kinetic equation to find the saturation state of parametric instabilities when it is assumed only that the wave intensity has axial symmetry about the pump field in wave number space. Calculations are presented of the magnitude of the nonlinear energy absorption and of the angular dependence, frequency spectrum, and intensity of scattering from instability-created density fluctuations. In the present experiments the nonlinear processes are predicted to absorb roughly 30% of the radio wave energy incident on the ionosphere. As a rule, this energy is deposited in the high-energy tail of the electron velocity distribution and causes enhanced airglow. The scattered radiation has a frequency shift almost equal to the modifier frequency, and its intensity depends strongly on the angle between k and E0, k being the wave vector of the plasma wave responsible for the scattering and E0 the pumping electric field produced by the modification transmitter. Because the instabilities occur only with O mode transmissions, the direction of E0 is close to the geomagnetic field. The angular dependence result rests on a combination of two-dimensional saturation calculations and plasma wave refraction due to propagation in the inhomogeneous magnetoactive ionospheric plasma. For example, the plasma waves responsible for the scattering observed at Arecibo are found to be nonlinearly stabilized and roughly 104 times less intense than plasma waves propagating within 20 of the geomagnetic field. Thus the scattering observed at Arecibo, although it is intense by Thomson scatter standards, is predicted to be ~40 dB below the scattering observable in the most favorable geometry. Lastly, new aeronomy experiments made possible by parametric instabilities are discussed.
BibTeX:
@article{Perkins1974,
  author = {Perkins, F. W. and Oberman, C. and Valeo, E. J.},
  title = {Parametric instabilities and ionospheric modification},
  journal = {Journal of Geophysical Research},
  year = {1974},
  volume = {79},
  number = {10},
  pages = {1478-1496},
  url = {http://dx.doi.org/10.1029/JA079i010p01478},
  doi = {10.1029/JA079i010p01478}
}
Rowe JF (1974), "Magnetic activity variations of the nighttime E region at Arecibo", Radio Science. Vol. 9(2), pp. 175-182.
Abstract: Using 13-bit Barker-coded pulses, high resolution (0.9 km) incoherent scatter measurements of nighttime E- and F-region electron densities have been conducted at Arecibo. Electron density profile sequences are presented for four nights characterized by a wide range of magnetic activity. The data show a deep valley in electron density above 120 km during quiet periods which fills in with plasma to levels of 1e4 cm-3 during a magnetic storm (Kp~8). An intermediate layer frequently appears near 125 km, independently of magnetic activity. In view of the observations, the connection between nighttime valley content and magnetic activity is discussed.
BibTeX:
@article{Rowe1974a,
  author = {Rowe, John F.},
  title = {Magnetic activity variations of the nighttime E region at Arecibo},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {2},
  pages = {175-182},
  url = {http://dx.doi.org/10.1029/RS009i002p00175},
  doi = {10.1029/RS009i002p00175}
}
Rowe Jr JF (1974), "Downward transport of nighttime Es-layers into the lower E-region at Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 36, pp. {225-234}.
BibTeX:
@article{RoweJr1974,
  author = {Rowe Jr, J F},
  title = {Downward transport of nighttime Es-layers into the lower E-region at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1974},
  volume = {36},
  pages = {225-234},
  doi = {10.1016/0021-9169(74)90042-7}
}
Sipler DP, Enemark E and Biondi MA (1974), "6300-å intensity variations produced by the Arecibo Ionospheric Modification Experiment", Journal of Geophysical Research. Vol. 79(28), pp. 4276-4280.
Abstract: Nightglow 6300-å intensity suppression and enhancement transients have been observed in conjunction with heating of the F region ionospheric electrons in Arecibo ionospheric modification experiments (IME). Ohmic heating of the electrons during X mode propagation of the heating wave results in a ?1.3% suppression of intensity, in semiquantitative agreement with the suppression predicted for ?Te ? 130°K (measured by the backscatter radar). The 6300-å intensity enhancements (?6 R) associated with O mode propagation of the heating wave are far too large to be produced by ohmic heating (a value ?Te ? 900°K, about 5 times larger than the backscatter measured value, would be required), suggesting electron acceleration by strong plasma waves that are generated by the heating RF wave. The O(¹D) lifetimes determined from the time constants of the 6300-å intensity enhancement transients yield an F region quenching coefficient k(N2) ? 6 to 8 â 10?11 cm¨/s, in good agreement with the Platteville IME and with laboratory results.
BibTeX:
@article{Sipler1974,
  author = {Sipler, Dwight P. and Enemark, E. and Biondi, Manfred A.},
  title = {6300-å intensity variations produced by the Arecibo Ionospheric Modification Experiment},
  journal = {Journal of Geophysical Research},
  year = {1974},
  volume = {79},
  number = {28},
  pages = {4276-4280},
  url = {http://dx.doi.org/10.1029/JA079i028p04276},
  doi = {10.1029/JA079i028p04276}
}
Swartz WE, Ioannidis GA, Shen JS, Brice NM and Rowe JF (1974), "Two days in the life of the ionosphere over Arecibo", Radio Science. Vol. 9(8-9), pp. 769-775.
Abstract: High resolution incoherent scatter electron density data using Barker-coded pulses are presented for two separate 24-hr periods of very different magnetic conditions. The first period in April 1972 was magnetically quiet while the second period spanned parts of two of the five most magnetically disturbed days in July 1972. Solar activity was low with 2800-MHz indices of 129 and 128 for the April days and indices of 109 and 117 for the July days. Contour plots and selected profiles are presented which show larger sporadic-E layers and stronger gravity wave effects during the disturbed night than during the quiet night.
BibTeX:
@article{Swartz1974,
  author = {Swartz, Wesley E. and Ioannidis, George A. and Shen, Jenny S. and Brice, Neil M. and Rowe, John F.},
  title = {Two days in the life of the ionosphere over Arecibo},
  journal = {Radio Science},
  year = {1974},
  volume = {9},
  number = {8-9},
  pages = {769-775},
  url = {http://dx.doi.org/10.1029/RS009i008p00769},
  doi = {10.1029/RS009i008p00769}
}
Taylor G and Risk K (1974), "Empirical relationships between F-region electron density and temperature at Malvern", Journal of Atmospheric and Terrestrial Physics . Vol. 36(8), pp. 1427-1430.
BibTeX:
@article{Taylor1974,
  author = {G.N. Taylor and K.J. Risk},
  title = {Empirical relationships between F-region electron density and temperature at Malvern},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1974},
  volume = {36},
  number = {8},
  pages = {1427-1430},
  doi = {10.1016/0021-9169(74)90220-7}
}
Behnke RA and Harper RM (1973), "Vector measurements of F region ion transport at Arecibo", Journal of Geophysical Research. Vol. 78(34), pp. 8222-8234.
Abstract: Vector measurements of the ion transport velocity in the F region above Arecibo (18°N, 50° dip angle) are reported for two daytime and five nighttime periods. From these vector measurements both the electric fields and neutral winds in the F region can be found. Daytime results indicate eastward electric fields during the morning, changing to westward near 1400. The most outstanding feature of the nighttime results is a large (~3 mv/m) westward electric field at 0400. The overall diurnal electric field pattern suggests that an 8-hour tidal mode dominates the wind fields in the dynamo region. Daytime neutral wind measurements indicate the importance of ion drag in determining the neutral winds; the poleward winds are observed to be strongest at ~1000, though, according to satellite drag data and evidence presented here, the N-S neutral pressure gradient maximizes in the afternoon. At night the neutral winds are first seen to blow strongly equatorward but then abate and often blow poleward by 0200. Application of the neutral wind and electric field measurements to F region morphology indicates that (1) during sunset strong downward ion transport is the result of poleward neutral winds; (2) the generally occurring (at Arecibo) sudden drop in the height of the F layer near midnight is the result of a reversing wind from equatorward to poleward; and (3) the rise of the F layer often seen at ~0400 at Arecibo is the result of E â B drifts. Finally, there is a strong tendency for the ion motion to be horizontal. Possible reasons for this behavior are discussed.
BibTeX:
@article{Behnke1973,
  author = {Behnke, Richard A. and Harper, Robert M.},
  title = {Vector measurements of F region ion transport at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1973},
  volume = {78},
  number = {34},
  pages = {8222-8234},
  url = {http://dx.doi.org/10.1029/JA078i034p08222},
  doi = {10.1029/JA078i034p08222}
}
Brice NM, Conrad JC, LaLonde LM and Steinfeld AH (1973), "Two-beam observations of ionospheric irregularity structure and velocity at Arecibo", Radio Science. Vol. 8(1), pp. 39-46.
Abstract: A new technique has been developed for measuring irregularity structure and velocity in the ionospheric E and F regions. The Arecibo incoherent-scatter radar was modified to measure electron-density profiles simultaneously with two beams: one fixed beam pointed at the zenith, and a second beam could be varied over 360° in azimuth and from 2 to 20° in zenith angle. Fluctuations in ionization density were observed to drift from one beam to the other so that information was obtained about both the horizontal velocity and the structure of these disturbances. Velocities of 100 to 200 m sec-1 and horizontal scale sizes of 50 to 100 km were deduced for the E region and roughly 400 m sec?1 and 500 km for the F region. A plot of velocity versus altitude shows a spiral structure with a vertical wavelength of 20 to 30 km in the E region.
BibTeX:
@article{Brice1973,
  author = {Brice, N. M. and Conrad, J. C. and LaLonde, L. M. and Steinfeld, A. H.},
  title = {Two-beam observations of ionospheric irregularity structure and velocity at Arecibo},
  journal = {Radio Science},
  year = {1973},
  volume = {8},
  number = {1},
  pages = {39-46},
  url = {http://dx.doi.org/10.1029/RS008i001p00039},
  doi = {10.1029/RS008i001p00039}
}
Harper R (1973), "Nighttime meridional neutral winds near 350 km at low to mid-latitudes", Journal of Atmospheric and Terrestrial Physics . Vol. 35(11), pp. 2023-2034.
Abstract: Nighttime measurements of the ion velocity at Arecibo (18°N, 50° dip) are presented for equinox conditions. The meridional component of the neutral wind is inferred from the ion velocity component along the magnetic field and the simultaneously measured electron density profiles and electron and ion temperatures. Strong equatorward winds are inferred in the 2100–2400 hr sector. The equatorward wind decreases rapidly after midnight and a weak reversal to poleward flow is usually observed near 0200–0300 hr. The latitudinal variation of the wind reversal is investigated using monthly means of F-layer height from stations in the American sector. Possible causes of the wind reversal are discussed.
BibTeX:
@article{Harper1973,
  author = {R.M Harper},
  title = {Nighttime meridional neutral winds near 350 km at low to mid-latitudes},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1973},
  volume = {35},
  number = {11},
  pages = {2023-2034},
  url = {http://www.sciencedirect.com/science/article/pii/0021916973901165},
  doi = {10.1016/0021-9169(73)90116-5}
}
McClure JP, Hanson WB, Nagy AF, Cicerone RJ, Brace LH, Baron M, Bauer P, Carlson HC, Evans JV, Taylor GN and Woodman RF (1973), "Comparison of Te and Ti from Ogo 6 and from various incoherent scatter radars", Journal of Geophysical Research. Vol. 78(1), pp. 197-205.
Abstract: Langmuir probe and retarding potential analyzer (RPA) data on the electron and ion temperatures Te and Ti obtained from Ogo 6 are compared with Te and Ti values obtained from the incoherent scatter network. The satellite to radar temperature ratio TeS/TeR is 1.15 on the average for these comparisons. This discrepancy is larger than the uncertainties usually placed on the probe and radar Te values. It is, however, a smaller discrepancy than that found in many previous comparisons of this type. Our data do not appear to give any insight into the cause of the discrepancy. The ion temperature ratio TiS/TiR is approximately 1.0, independent of the particular radar examined. The internal accuracy of the RPA Ti data set was ±5% or better. Thus this comparison serves as an intercalibration of the incoherent scatter network. Since no significant systematic errors (i.e., errors larger than the statistical errors) exist between the RPA and radar Ti data, it appears very unlikely that any significant systematic errors exist in either data set. It should be noted, however, that the comparison data were limited to mainly nighttime hours and thus to relatively low temperatures and were heavily weighted to altitudes between 400 and 600 km, where suspected sources of systematic error are minimum.
BibTeX:
@article{McClure1973,
  author = {McClure, J. P. and Hanson, W. B. and Nagy, A. F. and Cicerone, R. J. and Brace, L. H. and Baron, M. and Bauer, P. and Carlson, H. C. and Evans, J. V. and Taylor, G. N. and Woodman, R. F.},
  title = {Comparison of Te and Ti from Ogo 6 and from various incoherent scatter radars},
  journal = {Journal of Geophysical Research},
  year = {1973},
  volume = {78},
  number = {1},
  pages = {197-205},
  url = {http://dx.doi.org/10.1029/JA078i001p00197},
  doi = {10.1029/JA078i001p00197}
}
Rowe JF (1973), "A statistical summary of Arecibo nighttime E region observations", Journal of Geophysical Research. Vol. 78(28), pp. 6811-6817.
Abstract: This letter presents a summary of nighttime sporadic E layer observations and integrated content measurements made at the Arecibo Observatory during the period February 1972 to January 1973. The data were obtained with the use of 13-bit Barker-coded incoherent scatter radar pulses, giving a height resolution of 900 meters. A description of the pulse compression technique and its capabilities has been given by Ioannidis and Farley [1972]. A total of 91 hours of data spanning 17 nights is incorporated in this summary. Descriptions of layer formation and motion seen on individual nights are in preparation and will be published separately.
BibTeX:
@article{Rowe1973,
  author = {Rowe, John F.},
  title = {A statistical summary of Arecibo nighttime E region observations},
  journal = {Journal of Geophysical Research},
  year = {1973},
  volume = {78},
  number = {28},
  pages = {6811-6817},
  url = {http://dx.doi.org/10.1029/JA078i028p06811},
  doi = {10.1029/JA078i028p06811}
}
Rowe JF and Mathews JD (1973), "Low-latitude nighttime E region conductivities", Journal of Geophysical Research. Vol. 78(31), pp. 7461-7470.
Abstract: Recent incoherent scatter electron density measurements made with 0.9 km altitude resolution Barker-coded pulses are combined with the Jacchia neutral atmosphere model to generate nighttime electrical conductivities for the lower ionosphere at Arecibo. Electron density profiles and derived conductivities are presented for nights characterized by low and high magnetic activity. A model for nighttime electron densities incorporating 17 nights of data is presented along with the computed electrical conductivities. The features of the model include: (1) a sharply defined lower boundary at 85 km, (2) a layer between 85 and 120 km having an average density of 2 â 10¨ cm3 and showing a weak symmetry about solar midnight due to the ionizing effect of scattered solar ultraviolet radiation, (3) a valley of low electron density above 120 km that is progressively filled in with ionization as magnetic activity increases, and (4) electron density enhancements in the upper E region occurring 4 hours after local midnight as a result of downward transport of plasma from the F region. Height-integrated conductivities calculated from the model and the two nights of observations are also given.
BibTeX:
@article{Rowe1973a,
  author = {Rowe, John F. and Mathews, John D.},
  title = {Low-latitude nighttime E region conductivities},
  journal = {Journal of Geophysical Research},
  year = {1973},
  volume = {78},
  number = {31},
  pages = {7461-7470},
  url = {http://dx.doi.org/10.1029/JA078i031p07461},
  doi = {10.1029/JA078i031p07461}
}
Salpeter EE (1973), "Heat transfer in nucleation theory", Journal of Chemical Physics. Vol. 58(10), pp. 4331-4337.
Abstract: In nucleation theory the rate of growth of droplets near the ``critical size'' is needed as a function of the supersaturation ratio and of the equilibration time for heat transfer to the carrier gas. If the droplet is sufficiently small, the latent heat deposited when one molecule is added heats the droplet sufficiently for the evaporation rate to be increased appreciably. It is shown that the net growth rate is ``exponentially small'' when the heat transfer rate is moderately slow, unless the supersaturation ratio exceeds a critical value. Approximations are derived for this small growth rate under various conditions.
BibTeX:
@article{Salpeter1972,
  author = {E. E. Salpeter},
  title = {Heat transfer in nucleation theory},
  journal = {Journal of Chemical Physics},
  year = {1973},
  volume = {58},
  number = {10},
  pages = {4331-4337},
  url = {http://dx.doi.org/10.1063/1.1678990},
  doi = {10.1063/1.1678990}
}
Swartz WE and Nisbet JS (1973), "Incompatibility of solar EUV fluxes and incoherent scatter measurements at Arecibo", Journal of Geophysical Research. Vol. 78(25), pp. 5640-5657.
Abstract: Photoionization rates have been calculated from recent solar EUV flux measurements and are compared with the electron-ion recombination rates estimated from electron density profiles and current reaction rates. These photoionization rates also provided the first step in calculating the photoelectron heating rates of the ambient electrons, which are compared with the cooling fates deduced from ion and electron temperature measurements at Arecibo. The effects of changes in the assumed neutral models, the rate coefficients, and the temperature measurements are discussed. Comparisons of the profiles of energy input and loss with similar profiles of ion production and recombination suggest that the solar EUV fluxes have been underestimated. These comparisons also imply lower molecular neutral densities in winter than in summer.
BibTeX:
@article{Swartz1973,
  author = {Swartz, Wesley E. and Nisbet, John S.},
  title = {Incompatibility of solar EUV fluxes and incoherent scatter measurements at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1973},
  volume = {78},
  number = {25},
  pages = {5640-5657},
  url = {http://dx.doi.org/10.1029/JA078i025p05640},
  doi = {10.1029/JA078i025p05640}
}
Wrenn GL, Clarck DH, Raitt WJ and Carlson Jr. HC (1973), "Modulation Langmuir probe and incoherent scatter radar measurements of ionospheric electron temperature", Journal of Atmospheric and Terrestrial Physics. Vol. 35, pp. 405-413.
Abstract: Results are presented from a comparative study of ionospheric electron temperatures measured by the modulation Langmuir probes on the satellites Explorer 31 and ESRO-IA, and various incoherent scatter radar stations. Agreement is found between the two techniques to within the quoted errors. The discrepancy between slow-sweep Langmuir probe and incoherent scatter radar techniques is discussed in the light of these new results.
BibTeX:
@article{Wrenn1973,
  author = {Wrenn, G. L. and Clarck, D. H. and Raitt, W. J. and Carlson, Jr., H. C.},
  title = {Modulation Langmuir probe and incoherent scatter radar measurements of ionospheric electron temperature},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1973},
  volume = {35},
  pages = {405-413},
  url = {http://www.sciencedirect.com/science/article/pii/0021916973900329},
  doi = {10.1016/0021-9169(73)90032-9}
}
Carlson HC, Gordon WE and Showen RL (1972), "High frequency induced enhancements of the incoherent scatter spectrum at Arecibo", Journal of Geophysical Research. Vol. 77(7), pp. 1242-1250.
Abstract: Observations are reported of enhancements of the incoherent scatter spectrum excited by strong high frequency (HF) radio waves. A number of enhancement characteristics, observed during an ionospheric heating experiment in January at Arecibo, are described. The enhancement spectrum includes: a strong narrow line displaced below the HF (5.62 MHz) by the frequency of the ion acoustic waves fi in the plasma (about 4 kHz); a broader line (about 30-kc width) and other weak lines near the HF; and a line near fi. Enhancements above thermal levels range above a factor of 104 and may be taken as verification of the HF excitation of parametric instabilities in the ionosphere. Significant time variations over scales of tens of µsec through hours were seen. Upshifted and downshifted enhanced plasma lines display asymmetries in intensity, width, power dependence, and decay rates (of the order of msec). The O-mode (but not the X-mode) excitation of these enhancements is of significance to heating experiments.
BibTeX:
@article{Carlson1972,
  author = {Carlson, Herbert C. and Gordon, William E. and Showen, Robert L.},
  title = {High frequency induced enhancements of the incoherent scatter spectrum at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1972},
  volume = {77},
  number = {7},
  pages = {1242-1250},
  url = {http://dx.doi.org/10.1029/JA077i007p01242},
  doi = {10.1029/JA077i007p01242}
}
Carlson HC (1972), "Predawn airglow enhancement project: Perspective.", Annales de Geophysique. Vol. 28, pp. 179-186.
BibTeX:
@article{Carlson1972a,
  author = {Carlson, H. C.},
  title = {Predawn airglow enhancement project: Perspective.},
  journal = {Annales de Geophysique},
  year = {1972},
  volume = {28},
  pages = {179-186},
  url = {http://adsabs.harvard.edu/abs/1972AnG....28..179C}
}
Carlson H and Walker JC (1972), "Electrodynamic drift in the nocturnal F-region ionosphere caused by conjugate point sunrise", Planetary and Space Science . Vol. 20(2), pp. 141-148.
Abstract: A rapid change in the electrical conductivity of the ionosphere occurs at the time of sunrise. When the conjugate point is in darkness, this change causes a change in the component of the dynamo electrostatic field normal to the sunrise line. This change in electrostatic field should cause a corresponding change in the vertical component of ion drift velocities in the F-region. The theory we develop predicts changes in ion drift velocities that are of the same order of magnitude, tens of meters per second, as the dynamo region winds. The effect may be detectable as an upward or downward movement of the nocturnal ionosphere at the time of conjugate point sunrise.
BibTeX:
@article{Carlson1972b,
  author = {H.C. Carlson and James C.G. Walker},
  title = {Electrodynamic drift in the nocturnal F-region ionosphere caused by conjugate point sunrise},
  journal = {Planetary and Space Science },
  year = {1972},
  volume = {20},
  number = {2},
  pages = {141-148},
  url = {http://www.sciencedirect.com/science/article/pii/0032063372900955},
  doi = {10.1016/0032-0633(72)90095-5}
}
Correspondent A (1972), "Heat probing at Arecibo", Nature. Vol. 237, pp. 487.
BibTeX:
@article{Correspondent1972,
  author = {A Correspondent},
  title = {Heat probing at Arecibo},
  journal = {Nature},
  year = {1972},
  volume = {237},
  pages = {487},
  doi = {10.1038/237487a0}
}
Farley DT (1972), "Multiple-Pulse Incoherent-Scatter Correlation Function Measurements", Radio Science. Vol. 7(6), pp. 661-666.
Abstract: For monostatic radar measurements of the correlation function in the lower ionosphere, suitably spaced short pulses must be transmitted in order to obtain adequate height resolution. The efficiency of the measurement is greatly increased if several (five or more) pulses, rather than the usual pair, are transmitted with a particular irregular spacing. With this procedure many delays (10 or more) can be studied simultaneously. The increase in number of lags more than compensates for the increase in clutter. Various such multipulse schemes are described and their merits compared. The rather formidable amount of data processing associated with these procedures often cannot be done with a general purpose computer but can easily be handled by special purpose digital devices.
BibTeX:
@article{Farley1972,
  author = {Farley, D. T.},
  title = {Multiple-Pulse Incoherent-Scatter Correlation Function Measurements},
  journal = {Radio Science},
  year = {1972},
  volume = {7},
  number = {6},
  pages = {661-666},
  url = {http://dx.doi.org/10.1029/RS007i006p00661},
  doi = {10.1029/RS007i006p00661}
}
Hagfors T and Gieraltowski GF (1972), "Stable electron density fluctuations in a plasma in the presence of a high-frequency electric field", Journal of Geophysical Research. Vol. 77(34), pp. 6791-6803.
Abstract: The recent series of ionospheric heating experiments conducted by NOAA in Boulder and by Rice University at the Arecibo Observatory have shown that a powerful high-frequency transmitter can excite parametric plasma instabilities in the ionosphere. In this paper a theory is developed to describe the changes in the fluctuation spectrum that take place for excitation levels below those required for the instabilities to develop. These stable changes, which can be predicted in detail from theory, might prove valuable as a diagnostic tool if they can be studied by incoherent scatter techniques. It is shown that the raised shoulders in the normal incoherent scatter spectrum can be strongly enhanced when the HF pump frequency is slightly above the plasma frequency. For sufficiently high pump power, these shoulders are transformed into lines upshifted and downshifted from the center frequency by an amount corresponding to the ion acoustic velocity, and they approach infinity at a critical HF field strength. When the pump frequency lies at the frequency for longitudinal electron plasma oscillations, a single maximum occurs in the spectrum centered on zero frequency offset. This maximum also approaches infinity for a critical pump field slightly higher than in the former case. A similar situation exists in the vicinity of a frequency offset either upward or downward from zero frequency by the pump frequency when the latter is near the plasma frequency. The ion acoustic features have counterparts in two spikes centered on the pump frequency but with the stronger spectral feature always on the zero frequency side of the pump. The zero frequency line in the ion acoustic spectrum has a counterpart at the pump frequency. The variation of the spectral shape with various parameters is illustrated by sets of curves in which one parameter is varied at a time. The height regions over which the stable distortions in the spectrum will occur in the ionosphere will normally be so thin that observation of the phenomenon by incoherent scatter techniques may be at best difficult. For a pump frequency near the maximum plasma frequency of the F layer, however, observation of the spectral distortion might be possible.
BibTeX:
@article{Hagfors1972,
  author = {Hagfors, T. and Gieraltowski, G. F.},
  title = {Stable electron density fluctuations in a plasma in the presence of a high-frequency electric field},
  journal = {Journal of Geophysical Research},
  year = {1972},
  volume = {77},
  number = {34},
  pages = {6791-6803},
  url = {http://dx.doi.org/10.1029/JA077i034p06791},
  doi = {10.1029/JA077i034p06791}
}
Harper RM (1972), "Observation of a large nighttime gravity wave at Arecibo", Journal of Geophysical Research. Vol. 77(7), pp. 1311-1315.
Abstract: The observation of a large nighttime gravity wave at Arecibo is reported, and velocity and temperature perturbations to the neutral atmosphere are inferred. An increase in the velocity perturbation with height is observed. An anomalous temperature increase occurred when the gravity wave encountered the meridional wind reversal that normally occurs after midnight at low latitudes.
BibTeX:
@article{Harper1972,
  author = {Harper, R. M.},
  title = {Observation of a large nighttime gravity wave at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1972},
  volume = {77},
  number = {7},
  pages = {1311-1315},
  url = {http://dx.doi.org/10.1029/JA077i007p01311},
  doi = {10.1029/JA077i007p01311}
}
Ioannidis G and Farley DT (1972), "LETTERS, Incoherent Scatter Observations at Arecibo Using Compressed Pulses", Radio Science. Vol. 7(7), pp. 763-766.
Abstract: Pulse-compression techniques are now being used successfully in incoherent observations at Arecibo. In most observations a 13-bit Barker code and 6-usec baud length are used, giving a compression ratio of 13 to 1 with very low range sidelobes and an altitude resolution of 0.9 km. A few of the first measurements with this technique are presented here and include observations of (a) the E region and sporadic E layers, (b) the D-region ledge near 80 km, and (c) narrow enhanced echoes associated with HF heating of the ionosphere.
BibTeX:
@article{Ioannidis1972,
  author = {Ioannidis, G. and Farley, D. T.},
  title = {LETTERS, Incoherent Scatter Observations at Arecibo Using Compressed Pulses},
  journal = {Radio Science},
  year = {1972},
  volume = {7},
  number = {7},
  pages = {763-766},
  url = {http://dx.doi.org/10.1029/RS007i007p00763},
  doi = {10.1029/RS007i007p00763}
}
Klostermeyer J (1972), "Comparison between observed and numerically calculated atmospheric gravity waves in the F-region ", Journal of Atmospheric and Terrestrial Physics . Vol. 34(8), pp. 1393-1401.
Abstract: In a recent paper the author described the numerical calculation of gravity wave propagation in a thermospheric model. In the present paper calculated perturbation profiles of the electron density, the ion velocity, and the ion temperature are compared with experimental data obtained from the Thomson scatter facilities in Arecibo (Puerto Rico) and Saint-Santin (France). There is good agreement between calculated and observed results indicating that the numerical solutions represent a realistic description of gravity wave perturbations in thermospheric regions.
BibTeX:
@article{Klostermeyer1972,
  author = {J. Klostermeyer},
  title = {Comparison between observed and numerically calculated atmospheric gravity waves in the F-region },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1972},
  volume = {34},
  number = {8},
  pages = {1393-1401},
  url = {http://www.sciencedirect.com/science/article/pii/002191697290195X},
  doi = {10.1016/0021-9169(72)90195-X}
}
Mathews JD and Harper RM (1972), "Incoherent scatter radar observations of spred-F producing ionospheric structures at Arecibo", Journal of Atmospheric and Terrestrial Physics. Vol. 34, pp. {1,119-1,127}.
BibTeX:
@article{Mathews1972,
  author = {Mathews, J D and Harper, R M},
  title = {Incoherent scatter radar observations of spred-F producing ionospheric structures at Arecibo},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1972},
  volume = {34},
  pages = {1,119-1,127},
  doi = {10.1016/0021-9169(72)90100-6}
}
Showen RL (1972), "Artificial heating of the lower ionosphere", Journal of Geophysical Research. Vol. 77(10), pp. 1923-1933.
Abstract: The lower ionosphere has been heated in a controlled experiment at the Arecibo Observatory. A 1-Mw 40-mHz transmitter causes detectable heating from 80 to 120 km, and at 90 km the ambient electron temperature can be doubled. The 430-mHz radar backscatter system is used to measure the increase in electron temperature. Heating can be observed only in the daytime when the E region is present. Experiments with heating pulse lengths of 0.5–5 msec confirm predictions of the magnitude of heating if it is assumed that the heating is caused by collisions of the electrons with neutral molecules. Profiles of the deduced electron-neutral collision frequency are given. Thermal relaxation times are measured to determine the cooling parameter G, and the results agree with cross-modulation experiments at lower altitudes.
BibTeX:
@article{Showen1972,
  author = {Showen, Robert L.},
  title = {Artificial heating of the lower ionosphere},
  journal = {Journal of Geophysical Research},
  year = {1972},
  volume = {77},
  number = {10},
  pages = {1923-1933},
  doi = {10.1029/JA077i010p01923}
}
Swartz W, Rohrbaugh J and Nisbet J (1972), "A thermospheric model from satellite orbital decay densities and incoherent scatter temperatures", Journal of Atmospheric and Terrestrial Physics. Vol. 34(10), pp. 1817-1826.
BibTeX:
@article{Swartz1972,
  author = {W.E. Swartz and J.L. Rohrbaugh and J.S. Nisbet},
  title = {A thermospheric model from satellite orbital decay densities and incoherent scatter temperatures},
  journal = {Journal of Atmospheric and Terrestrial Physics},
  year = {1972},
  volume = {34},
  number = {10},
  pages = {1817-1826},
  doi = {10.1016/0021-9169(72)90036-0}
}
Wickwar VB (1972), "The 6300 A Predawn enhancement : excitation by photoelectrons from the Magnetic conjugate point", Annales de Geophysique. Vol. 27(1), pp. 187-192.
BibTeX:
@article{Wickwar1972,
  author = {Vincent B. Wickwar},
  title = {The 6300 A Predawn enhancement : excitation by photoelectrons from the Magnetic conjugate point},
  journal = {Annales de Geophysique},
  year = {1972},
  volume = {27},
  number = {1},
  pages = {187-192},
  url = {http://adsabs.harvard.edu/abs/1972AnG....28..187W}
}
Brice N and Lucas C (1971), "Influence of magnetospheric convection and polar wind on loss of electrons from the outer radiation belt", Journal of Geophysical Research. Vol. 76(4), pp. 900-908.
BibTeX:
@article{Brice1971,
  author = {Brice, Neil and Lucas, Christopher},
  title = {Influence of magnetospheric convection and polar wind on loss of electrons from the outer radiation belt},
  journal = {Journal of Geophysical Research},
  year = {1971},
  volume = {76},
  number = {4},
  pages = {900-908},
  doi = {10.1029/JA076i004p00900}
}
Gordon WE, Showen R and Carlson HC (1971), "Ionospheric heating at Arecibo: First tests", Journal of Geophysical Research. Vol. 76(31), pp. 7808-7813.
BibTeX:
@article{Gordon1971,
  author = {Gordon, W. E. and Showen, R. and Carlson, H. C.},
  title = {Ionospheric heating at Arecibo: First tests},
  journal = {Journal of Geophysical Research},
  year = {1971},
  volume = {76},
  number = {31},
  pages = {7808-7813},
  url = {http://dx.doi.org/10.1029/JA076i031p07808},
  doi = {10.1029/JA076i031p07808}
}
Ho MC and Moorcroft DR (1971), "Hydrogen density and proton flux in the topside ionosphere over Arecibo, Puerto Rico, from incoherent scatter observations", Planetary and Space Science. Vol. 19, pp. 1441-1455.
Abstract: Incoherent scatter observations of the topside ionosphere over Arecibo, Puerto Rico, have been analyzed and interpreted to give values for the neutral hydrogen density and vertical proton flux throughout a 30 hr period on December 7 and 8, 1965.
The neutral hydrogen density is of the order of 106 cm-3 at 520km, agreeing well with other recent measurements. A diurnal variation of about 2-1 was found, which confirms recent theoretical predictions.
The vertical proton flux attained a maximum value of about 109 cm-2 sec-1, being upward in the daytime and downward at night. The daytime flux appears to be of comparable magnitude with the limiting flux permitted, but the shape of the ion density profile suggests that the flux was not actually a limiting flux. For the night in question, the downward proton flux appears to account for the maintenance of the F layer, perhaps with some additional contribution from neutral winds and/or electric fields.
BibTeX:
@article{Ho1971,
  author = {Ho, M C and Moorcroft, D R},
  title = {Hydrogen density and proton flux in the topside ionosphere over Arecibo, Puerto Rico, from incoherent scatter observations},
  journal = {Planetary and Space Science},
  year = {1971},
  volume = {19},
  pages = {1441-1455},
  url = {http://dx.doi.org/10.1016/0032-0633(71)90005-5},
  doi = {10.1016/0032-0633(71)90005-5}
}
Nelson G and Cogger L (1971), "Dynamical behaviour of the nighttime ionosphere at Arecibo ", Journal of Atmospheric and Terrestrial Physics . Vol. 33(11), pp. 1711-1726.
BibTeX:
@article{Nelson1971,
  author = {G.J. Nelson and L.L. Cogger},
  title = {Dynamical behaviour of the nighttime ionosphere at Arecibo },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1971},
  volume = {33},
  number = {11},
  pages = {1711-1726},
  doi = {10.1016/0021-9169(71)90219-4}
}
Nelson GJ and Cooger LL (1971), "Enhancements in electron content at Arecibo during geomagnetic storms", Planetary and Space Science. Vol. 19, pp. 761-775.
Abstract: A phenomenon has been observed at Arecibo, Puerto Rico in which the total electron content of the ionosphere, in a column nearly parallel to the geomagnetic field, is enhanced in the afternoon or night during a magnetic disturbance. The enhancement is associated with the large negative excursion in the H component of the local geomagnetic field induced by the ring current.
The enhancements which occur at night begin simultaneously with a downward motion of the F layer. This motion however is not a disturbance phenomenon as it is observed on 85 per cent of all nights at Arecibo regardless of magnetic activity. The downward motion and the enhancement in electron content which accompanies it on disturbed nights commence later in local time at higher latitudes.
Neither north-south nor east-west motions of ionization appear to be able to explain the nighttime enhancements unless in the latter case eastward winds with velocities greater than 500 m/sec exist. Diffusion of ionization from the protonosphere and direct ionization have also been excluded as possible mechanisms.
BibTeX:
@article{Nelson1971a,
  author = {Nelson, G J and Cooger, L L},
  title = {Enhancements in electron content at Arecibo during geomagnetic storms},
  journal = {Planetary and Space Science},
  year = {1971},
  volume = {19},
  pages = {761-775},
  url = {http://dx.doi.org/10.1016/0032-0633(71)90034-1},
  doi = {10.1016/0032-0633(71)90034-1}
}
Steinfeld AH, Brice NM, Conrad JC and LaLonde LM (1971), "Theoretical and Experimental Determination of the Near-Field Correction for Backscatter Gain at the Arecibo Observatory", Radio Science. Vol. 6(12), pp. 1079-1084.
Abstract: During the summer of 1968, two-beam, incoherent-scatter radar measurements were made at Arecibo. The two beams were formed by two separate feeds for the Arecibo reflector, one a line feed which illuminated essentially all of the reflector, and the other a horn feed which effectively illuminated about 500 feet of the reflector. A by-product of this experiment was the calibration of the near-field correction to the backscatter gain of the line-feed system. This was obtained by comparing the power received as a function of range in the two radar systems. The measured loss of gain in the near field for the line feed was about 1.5 db at a height of 100 km.
BibTeX:
@article{Steinfeld1971,
  author = {Steinfeld, A. H. and Brice, N. M. and Conrad, J. C. and LaLonde, L. M.},
  title = {Theoretical and Experimental Determination of the Near-Field Correction for Backscatter Gain at the Arecibo Observatory},
  journal = {Radio Science},
  year = {1971},
  volume = {6},
  number = {12},
  pages = {1079-1084},
  url = {http://dx.doi.org/10.1029/RS006i012p01079},
  doi = {10.1029/RS006i012p01079}
}
Swartz WE and Nisbet JS (1971), "Diurnal variation of the neutral temperature profile at Arecibo from incoherent scatter measurements and its relevance to the 1400-hour density maximum", Journal of Geophysical Research. Vol. 76(1), pp. 185-196.
Abstract: Series of high-resolution electron and ion temperature and electron density measurements at Arecibo have been used to derive profiles of the neutral temperature from 116 km to 400 km throughout the day. In this technique, least squares fitting is used to calculate a smooth temperature profile and a neutral atmospheric model. The availability of a complete profile allows calculation of the thermal energy storage and downward heat conduction throughout the day. Two methods have been employed to calculate the density profile. The first assumes that the density at 120 km is known and solves for the diffusion equilibrium model that best fits the data. The second method requires only the assumption of the relative densities of the neutral constituents at the lower boundary but has a somewhat higher experimental variance. It is shown that density and temperature do not generally peak at the same time, though current atmospheric models such as Cira 1965 suggest that they do. These models are based mainly on satellite orbital decay measurements and indicate a density maximum around 1400 hours. Neutral temperatures derived from incoherent sounding have indicated a temperature maximum near 1600 hours. It is now suggested that these two phenomena may be self consistent when the entire temperature profile affecting the neutral density is considered.
BibTeX:
@article{Swartz1971,
  author = {Swartz, Wesley E. and Nisbet, John S.},
  title = {Diurnal variation of the neutral temperature profile at Arecibo from incoherent scatter measurements and its relevance to the 1400-hour density maximum},
  journal = {Journal of Geophysical Research},
  year = {1971},
  volume = {76},
  number = {1},
  pages = {185-196},
  url = {http://dx.doi.org/10.1029/JA076i001p00185},
  doi = {10.1029/JA076i001p00185}
}
Waldteufel P and Cogger L (1971), "Measurements of the neutral temperature at Arecibo", Journal of Geophysical Research. Vol. 76(22), pp. 5322-5336.
Abstract: Ionospheric observations made at Arecibo from 1965 to 1970 are examined to derive the experimental behavior of the netural temperature. The systematic variations of this parameter, as well as the results of comparisons with simultaneous middle latitude measurements, help to strengthen and better define the existing description of the neutral atmosphere from incoherent scatter observations. Implications of the new results concerning the lower thermosphere are discussed.
BibTeX:
@article{Waldteufel1971,
  author = {Waldteufel, P. and Cogger, L.},
  title = {Measurements of the neutral temperature at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1971},
  volume = {76},
  number = {22},
  pages = {5322-5336},
  url = {http://dx.doi.org/10.1029/JA076i022p05322},
  doi = {10.1029/JA076i022p05322}
}
Carlson HC and Sayers J (1970), "Discrepancy in electron temperatures deduced from Langmuir Probes and from incoherent scatter radars", Journal of Geophysical Research. Vol. 75(25), pp. 4883-4886.
Abstract: In this note two comments are made about the disturbing discrepancy between incoherent scatter radar and satellite-borne Langmuir probe measurements of electron temperatures. First, it is noted that the discrepancy is not necessarily randomly variable or necessarily dependent on the incoherent scatter station, satellite, or geophysical conditions as has been speculated in the past. Rather, the two temperatures may be simply related. Second, it is noted that, although a great deal of attention has been devoted to the plasma physics of the Langmuir probe in space, it would seem that more effort might be warranted in the surface physics aspects of the probe experiment. Since the probe calibration depends on a linear fit to a log current versus voltage curve over only a few tenths of a volt and over a range of a few factors of 2, one should consider whether a local plasma disturbance by the probe or a probe surface contamination could significantly (on this scale) distort the current-voltage characteristic. Specifically, with regard to the current-voltage characteristic, the question of contact potential or work function drift is raised.
BibTeX:
@article{Carlson1970,
  author = {Carlson, H. C. and Sayers, J.},
  title = {Discrepancy in electron temperatures deduced from Langmuir Probes and from incoherent scatter radars},
  journal = {Journal of Geophysical Research},
  year = {1970},
  volume = {75},
  number = {25},
  pages = {4883-4886},
  url = {http://dx.doi.org/10.1029/JA075i025p04883},
  doi = {10.1029/JA075i025p04883}
}
Carlson HC, Harper R, Wickwar V, Showen R, Behnke R, Trost TF, Cogger LR and Nelson CJ (1970), "Eclipse Observations at Arecibo, Puerto Rico, on March 7, 1970", Nature. Vol. 226, pp. 1124-1125.
BibTeX:
@article{Carlson1970a,
  author = {Carlson, H C and Harper, R and Wickwar, V and Showen, R and Behnke, R and Trost, T. F. and Cogger, L R and Nelson, C J},
  title = {Eclipse Observations at Arecibo, Puerto Rico, on March 7, 1970},
  journal = {Nature},
  year = {1970},
  volume = {226},
  pages = {1124-1125},
  url = {http://www.nature.com/nature/journal/v226/n5251/abs/2261124a0.html},
  doi = {10.1038/2261124a0}
}
Cogger LL, Nelson GJ, Biondi MA, Hake RD and Sipler DP (1970), "Coincident F-region temperature determinations from incoherent backscatter and Doppler broadening of [O I] 6300 A", Journal of Geophysical Research. Vol. 75(25), pp. 4887-4889.
BibTeX:
@article{Cogger1970,
  author = {Cogger, L. L. and Nelson, G. J. and Biondi, M. A. and Hake, R. D. and Sipler, D. P.},
  title = {Coincident F-region temperature determinations from incoherent backscatter and Doppler broadening of [O I] 6300 A},
  journal = {Journal of Geophysical Research},
  year = {1970},
  volume = {75},
  number = {25},
  pages = {4887-4889},
  doi = {10.1029/JA075i025p04887}
}
Prasad SS (1970), "Ionic composition and temperature over Arecibo 2", Journal of Geophysical Research. Vol. 75(10), pp. 1911-1918.
Abstract: Results on the composition and temperature of the charged particles in the topside ionosphere over Arecibo, as obtained from the analysis of incoherent backscatter spectra gathered at the Arecibo Ionospheric Observatory during the period December 1965 through October 1967, are presented. Enhanced solar activity resulted in increased concentration of the heavier oxygen ions and thereby higher altitude for the O+ -- He+ and H+ transition level. The oxygen ions were important over a larger altitude range in summer than in winter. On winter nights the oxygen ion concentration began to rise even before local sunrise and continued to build up to early afternoon hours. In summer, however, the O+ concentration levels off within about two to three hours of sunrise. A marked altitude gradient in temperature existed during winter nights when some thermal nonequilibrium also was noticeable. In contrast, the entire ionosphere was practically isothermal during summer nights.
BibTeX:
@article{Prasad1970,
  author = {Prasad, S. S.},
  title = {Ionic composition and temperature over Arecibo 2},
  journal = {Journal of Geophysical Research},
  year = {1970},
  volume = {75},
  number = {10},
  pages = {1911-1918},
  url = {http://dx.doi.org/10.1029/JA075i010p01911},
  doi = {10.1029/JA075i010p01911}
}
Silverman S (1970), "Night airglow phenomenology", Space Science Reviews. Vol. 11(2-3), pp. 341-379.
Abstract: The phenomenology of the night airglow is reviewed with particular emphasis on the work of recent years. The major topics discussed are the spectrum; latitudinal dependency; diurnal variation; correlations in time and space; the effects of magnetic activity and of the sunspot cycle and solar activity; and conjugacy and the airglow. A number of other topics are also discussed briefly.
BibTeX:
@article{Silverman1970,
  author = {Silverman, S.M.},
  title = {Night airglow phenomenology},
  journal = {Space Science Reviews},
  year = {1970},
  volume = {11},
  number = {2-3},
  pages = {341-379},
  url = {http://dx.doi.org/10.1007/BF00241526},
  doi = {10.1007/BF00241526}
}
Smith DH (1970), "Diurnal variation of the mean Faraday factor at Arecibo", Journal of Geophysical Research. Vol. 75(4), pp. 823-828.
Abstract: Estimates of the total electron content of the ionosphere can be obtained from measurements of the Faraday rotation of VHF signals from a geostationary satellite. The accuracy of the estimates depends in part on the accuracy with which the mean value of the ‘Faraday factor’ M, is known. A description is given of a method of calculating this factor by making use of the electron number density profiles obtained from a backscatter radar installation. For a 30-hour period of observation at Arecibo in January 1969, it is shown that M had a predawn minimum nearly 30% lower than its daytime maximum. The diurnal variation of M did not show an inverse dependence on the hmax.
BibTeX:
@article{Smith1970,
  author = {Smith, D. H.},
  title = {Diurnal variation of the mean Faraday factor at Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1970},
  volume = {75},
  number = {4},
  pages = {823-828},
  url = {http://dx.doi.org/10.1029/JA075i004p00823},
  doi = {10.1029/JA075i004p00823}
}
Smith DH (1970), "The Comparison of Electron Density Profiles Obtained from Backscatter Observations and Ionogram Analysis", Radio Science. Vol. 5(4), pp. 685-692.
Abstract: A large number of ionograms recorded at Arecibo have been converted to electron density profiles. It is shown that the method of analysis can give very high accuracy for a single layer, but the presence of an E layer can result in systematic errors in the shape of the F layer. Backscatter observations taken at the same times as the ionograms have been analyzed to give electron density curves with a height resolution of 9 km. Although there is a wide range of variation in the shape and height of the ionospheric layers, there is in general close agreement between the profiles obtained by the two methods.
BibTeX:
@article{Smith1970a,
  author = {Smith, D. H.},
  title = {The Comparison of Electron Density Profiles Obtained from Backscatter Observations and Ionogram Analysis},
  journal = {Radio Science},
  year = {1970},
  volume = {5},
  number = {4},
  pages = {685-692},
  url = {http://dx.doi.org/10.1029/RS005i004p00685},
  doi = {10.1029/RS005i004p00685}
}
Wand R and Perkins F (1970), "Temperature and composition of the ionosphere: diurnal variations and waves", Journal of Atmospheric and Terrestrial Physics . Vol. 32(12), pp. 1921-1943.
BibTeX:
@article{Wand1970,
  author = {R.H. Wand and F.W. Perkins},
  title = {Temperature and composition of the ionosphere: diurnal variations and waves},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1970},
  volume = {32},
  number = {12},
  pages = {1921-1943},
  doi = {10.1016/0021-9169(70)90088-7}
}
Brace LH, Carlson HC and Mahajan KK (1969), "Radar backscatter and rocket probe measurements of electron temperature above Arecibo", Journal of Geophysical Research. Vol. 74(7), pp. 1883-1885.
BibTeX:
@article{Brace1969,
  author = {Brace, L. H. and Carlson, H. C. and Mahajan, K. K.},
  title = {Radar backscatter and rocket probe measurements of electron temperature above Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1969},
  volume = {74},
  number = {7},
  pages = {1883-1885},
  doi = {10.1029/JA074i007p01883}
}
Farley DT (1969), "Incoherent Scatter Correlation Function Measurements", Radio Science. Vol. 4(10), pp. 935-953.
Abstract: Single-pulse and double-pulse methods for measuring the cross-correlation (two polarizations transmitted and received) or auto-correlation (one polarization only) function of the scattered signal are described. The statistical errors associated with various forms of multi-bit (no quantization errors in the sampling process), one-bit, and hybrid estimators of the correlation function are calculated and compared, both for large and small signal-to-noise ratios. Roughly speaking, when the signal correlation is small, the hybrid estimators require H/2 and the one-bit H2/4 times as many independent samples as the multi-bit estimators to achieve the same statistical accuracy, but this disadvantage is often more than compensated for by an increase in the effective sampling rate. When the correlation is 0.5 or more, there may be a substantial difference between estimators of the same class (multi-bit, for example). Systematic distortions of the correlation function and limitations on resolution associated with the finite receiver bandwidth and transmitted pulse length are calculated. The effect of a refractive index slightly less than unity is mentioned.
BibTeX:
@article{Farley1969,
  author = {Farley, D. T.},
  title = {Incoherent Scatter Correlation Function Measurements},
  journal = {Radio Science},
  year = {1969},
  volume = {4},
  number = {10},
  pages = {935-953},
  url = {http://dx.doi.org/10.1029/RS004i010p00935},
  doi = {10.1029/RS004i010p00935}
}
Farley DT (1969), "Incoherent Scatter Power Measurements; a Comparison of Various Techniques", Radio Science. Vol. 4(2), pp. 139-142.
Abstract: The straightforward way to determine the mean scattered power is to square-law detect the incoming signal and average the results. This is also the optimum technique from a statistical point of view. Various other detection schemes are only slightly inferior, however, and may be substantially more convenient when the entire signal processing problem is considered. This paper examines the pros and cons of a number of these possibilities.
BibTeX:
@article{Farley1969a,
  author = {Farley, D. T.},
  title = {Incoherent Scatter Power Measurements; a Comparison of Various Techniques},
  journal = {Radio Science},
  year = {1969},
  volume = {4},
  number = {2},
  pages = {139-142},
  url = {http://dx.doi.org/10.1029/RS004i002p00139},
  doi = {10.1029/RS004i002p00139}
}
Farley DT (1969), "Faraday Rotation Measurements Using Incoherent Scatter", Radio Science. Vol. 4(2), pp. 143-152.
Abstract: A complete description is given of the method used at the Jicamarca Radar Observatory to derive Faraday rotation information (and hence absolute electron density profiles that do not require subsequent normalization or correction for the effects of Te/Ti) from incoherent scatter data. Similar techniques which could be used at other observatories with radars not having the unusual properties of the Jicamarca radar are discussed. At temperate and polar latitudes the optimum frequencies for incoherent scatter Faraday measurements in most of the ionosphere are roughly 100–200 MHz. Somewhat higher frequencies should give acceptable daytime results, however. A slight modification of the Faraday measurement, used at Jicamarca to obtain the autocorrelation function of the scattered signal, is also briefly described.
BibTeX:
@article{Farley1969b,
  author = {Farley, D. T.},
  title = {Faraday Rotation Measurements Using Incoherent Scatter},
  journal = {Radio Science},
  year = {1969},
  volume = {4},
  number = {2},
  pages = {143-152},
  url = {http://dx.doi.org/10.1029/RS004i002p00143},
  doi = {10.1029/RS004i002p00143}
}
Mahajan K (1969), "Diurnal variation of the ion temperature", Journal of Atmospheric and Terrestrial Physics . Vol. 31(1), pp. 93 - 101.
Abstract: Results on the diurnal variation of the ion temperature, obtained from the Thomson scatter spectra at Arecibo, in the height range 250–475 km are presented. At 250 km where the ion temperature (Ti) is expected to be nearly equal to the neutral temperature (Tn, Ti is generally observed to show diurnal maximum at 16 hr L.T. and diurnal minimum at 4 hr L.T., with no appreciable change in these times with solar activity. The average day to night Ti ratio at 250 km is found to be 1.45. These results are in apparent conflict with the satellite drag analysis in which Tn is found to have a diurnal maximum at 14 hr L.T. and day to night temperature ratio around 1.30. At 475 km where Ti, is significantly above Tn, the diurnal behavior of Ti is observed to be different on different days. The day-to-day and hour-to-hour variations in Ti at this height are found to be due to changes in the electron density and electron temperature and seem consistent in terms of an energy budget that includes heating of the ion gas by the hotter thermal electrons and cooling by the neutral atmosphere.
BibTeX:
@article{Mahajan1969,
  author = {K.K. Mahajan},
  title = {Diurnal variation of the ion temperature},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1969},
  volume = {31},
  number = {1},
  pages = {93 - 101},
  url = {http://www.sciencedirect.com/science/article/pii/0021916969900841},
  doi = {10.1016/0021-9169(69)90084-1}
}
Moorcroft DR (1969), "Nighttime topside ionic composition and temperature over Arecibo, Puerto Rico", Journal of Geophysical Research. Vol. 74(1), pp. 315-324.
Abstract: The ionic composition and temperature of the nighttime ionosphere over Arecibo, Puerto Rico, have been deduced from Thomson (incoherent) scatter spectra obtained with the radar at the Arecibo Ionospheric Observatory on seventeen nights between August 1965 and August 1966. At no time was more than 20% He+ detected at any height. In general, the transition from O+ to H+ was low (475 km) and abrupt in the winter and higher (675 km) and more gradual in the summer. Typically, the transition level (height where %O+ = %H+) lowered progressively during the summer nights, but showed a post-sunset increase during the winter nights. Analysis of this post-sunset increase indicates that it was due to a general increase in the height of the topside ionosphere, which occurred too rapidly for chemical equilibrium to be established. The resulting time constants imply a charge-exchange cross section of less than 9 â 10-16 ev cm-2 sec-1, a value smaller than previously assumed. The data for one winter night were analyzed in detail. An estimate of the downward heat flux agrees in magnitude and time variation with previous theoretical results on the cooling of the protonosphere. The composition profiles seem to imply a downward H+ flux comparable with estimates of the theoretical limit. However, observations at other times of the year suggest that other (unknown) effects may complicate the interpretation of composition profiles.
BibTeX:
@article{Moorcroft1969,
  author = {Moorcroft, D. R.},
  title = {Nighttime topside ionic composition and temperature over Arecibo, Puerto Rico},
  journal = {Journal of Geophysical Research},
  year = {1969},
  volume = {74},
  number = {1},
  pages = {315-324},
  url = {http://dx.doi.org/10.1029/JA074i001p00315},
  doi = {10.1029/JA074i001p00315}
}
Thome G (1969), "Correction to paper by George Thome, Long-period waves generated in the polar ionosphere during the onset of magnetic storms", Journal of Geophysical Research. Vol. 74(7), pp. 1891-1891.
BibTeX:
@article{Thome1969,
  author = {Thome, George},
  title = {Correction to paper by George Thome, Long-period waves generated in the polar ionosphere during the onset of magnetic storms},
  journal = {Journal of Geophysical Research},
  year = {1969},
  volume = {74},
  number = {7},
  pages = {1891-1891},
  doi = {10.1029/JA074i007p01891-01}
}
Wand RH (1969), "Evidence for reversible heating in the E region from radar Thomson scatter observations of ion temperature", Journal of Geophysical Research. Vol. 74(24), pp. 5688-5696.
Abstract: Values of ion temperature (Ti) and ion-neutral collision frequency (v) in the daytime E region have been obtained from radar Thomson scatter measurements at the Arecibo Ionospheric Observatory. These quantities were deduced from the shape of the autocorrelation function of the backscattered signal that was measured with a height resolution of 15 km using a double-pulse technique. Usually the daily variation of Ti at 115 and 130 km exhibited wave-like structure that must also have been present in the neutral atmosphere because the ion and neutral constituents have the same temperature at these altitudes. The observed temperature oscillations are interpreted as a manifestation of the reversible adiabatic heating accompanying long-period internal gravity waves in the neutral atmosphere. A simple harmonic analysis of the temperatures for a number of days gives dominant wave periods of from 7 to 13 hours and fractional amplitudes as large as 22%. On the reversible heating explanation, the observed amplitudes of the temperature waves imply average horizontal wind amplitudes of 60 to 70 m/sec. A downward phase progression (corresponding to upward energy propagation) is evident with an average vertical wavelength near 60 km. A significant wave-like variation is also detected in some of the ion-neutral collision frequency results at 115 km. The period is similar to that of the corresponding temperature wave, but the fractional amplitude is larger, and there is an appreciable phase difference. The phase and amplitude of the variation in the neutral concentration, as predicted from the collision frequency variation using the polarization ion-neutral interaction, does not agree with that deduced from the temperature variation using simple internal gravity wave theory with upward energy propagation. The resolution of this discrepancy may depend on the removal of Some of the idealizations in the gravity wave theory or the inclusion of additional ion-neutral interaction terms.
BibTeX:
@article{Wand1969,
  author = {Wand, R. H.},
  title = {Evidence for reversible heating in the E region from radar Thomson scatter observations of ion temperature},
  journal = {Journal of Geophysical Research},
  year = {1969},
  volume = {74},
  number = {24},
  pages = {5688-5696},
  doi = {10.1029/JA074i024p05688}
}
Axford W (1968), "Observations of the interplanetary plasma", Space Science Reviews. Vol. 8(3), pp. 331-365.
BibTeX:
@article{Axford1968,
  author = {Axford, W.I.},
  title = {Observations of the interplanetary plasma},
  journal = {Space Science Reviews},
  year = {1968},
  volume = {8},
  number = {3},
  pages = {331-365},
  doi = {10.1007/BF00184740}
}
Doupnik J and Nisbet J (1968), "Fluctuations of electron density in the daytime F-region", Journal of Atmospheric and Terrestrial Physics . Vol. 30(5), pp. 931-961.
Abstract: Further work on the large electron density and electron temperature fluctuations observed on quiet summer and winter days is reported.

The data are examined in relation to explanations based on electrodynamic effects, neutral wind variations, gravity waves, and movement of ionospherie irregularities over the site. The characteristics of the fluctuations, as measured at Arecibo, have been supplemented by ionosonde data at other sites.

Vertical transport velocities have been calculated based on the assumption that the fluctuations represent a time term variation by the solution of the F-region continuity equation from 250 km to 700 km. CIRA 1965 neutral atmosphere models together with current estimates of the solar flux and loss rate coefficients have been employed. The vertical velocities calculated in this way have been compared with estimates based on magnetograms from San Juan, neutral wind velocities, E- and F-region drifts measurements by the method of similar fades in Puerto Rico, and with measurements made at Arecibo by Thome using antenna rotation.

BibTeX:
@article{Doupnik1968,
  author = {J.R. Doupnik and J.S. Nisbet},
  title = {Fluctuations of electron density in the daytime F-region},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1968},
  volume = {30},
  number = {5},
  pages = {931-961},
  url = {http://www.sciencedirect.com/science/article/pii/S0021916968800455},
  doi = {10.1016/S0021-9169(68)80045-5}
}
Mahajan KK, Rao PB and Prasad SS (1968), "Incoherent backscatter study of electron content and equivalent slab thickness", Journal of Geophysical Research. Vol. 73(7), pp. 2477-2486.
Abstract: Results of electron content and equivalent slab thickness obtained from radar backscatter measurements at Arecibo (18.4°N, 67°W) are presented and examined in the light of other simultaneously observed parameters, such as the height of the F-layer peak and electron and ion temperatures. There is a considerable day-to-day variability both in the electron content and the equivalent slab thickness. The daytime electron content shows a strong positive correlation with the height of the F-layer peak, hmF2, which seems to be due to decrease in the integrated loss rates with increasing peak height. The post sunset decay of the electron content provides a mean effective attachment coefficient of 8 â 10-5 sec-1. The post midnight enhancements, observed mainly during the winter nights, require downward electron fluxes of about 2.5 â 1012 m-2 sec-1 at the height of 700 km. The slab thickness during the nighttime shows a strong dependence upon hmF2 and is very closely related to the neutral scale height at the peak. The daytime slab thickness, however, is controlled jointly by the neutral scale height and the extent of thermal nonequilibrium.
BibTeX:
@article{Mahajan1968,
  author = {Mahajan, K. K. and Rao, P. B. and Prasad, S. S.},
  title = {Incoherent backscatter study of electron content and equivalent slab thickness},
  journal = {Journal of Geophysical Research},
  year = {1968},
  volume = {73},
  number = {7},
  pages = {2477-2486},
  url = {http://dx.doi.org/10.1029/JA073i007p02477},
  doi = {10.1029/JA073i007p02477}
}
Prasad SS (1968), "Nighttime ionic composition and temperature over Arecibo", Journal of Geophysical Research. Vol. 73(21), pp. 6795-6807.
Abstract: Results on the composition and temperature of the charged particles in the nighttime topside ionosphere, as obtained from the analysis of incoherent backscatter spectra gathered over the period December 1965 through October 1967 at the Arecibo Ionospheric Observatory are presented. With the growth of solar activity the oxygen to light ion transition altitude went up, the relative abundance of helium ions increased, and the region over which the helium ions occur became thicker. Relative to winter, the oxygen ions were important over a larger altitude range in summer. In winter nights the oxygen ion concentration began to rise even before the local sunrise. Marked altitude gradient in temperature existed during winter nights. In contrast the whole of the ionosphere under observation was isothermal in summer.
BibTeX:
@article{Prasad1968,
  author = {Prasad, S. S.},
  title = {Nighttime ionic composition and temperature over Arecibo},
  journal = {Journal of Geophysical Research},
  year = {1968},
  volume = {73},
  number = {21},
  pages = {6795-6807},
  url = {http://dx.doi.org/10.1029/JA073i021p06795},
  doi = {10.1029/JA073i021p06795}
}
Rao P (1968), "Night-time plasma transport in the topside ionosphere using backscatter Nh profiles", Journal of Atmospheric and Terrestrial Physics . Vol. 30(7), pp. 1415-1427.
BibTeX:
@article{Rao1968,
  author = {P.B. Rao},
  title = {Night-time plasma transport in the topside ionosphere using backscatter Nh profiles},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1968},
  volume = {30},
  number = {7},
  pages = {1415-1427},
  doi = {10.1016/S0021-9169(68)91277-4}
}
Thome G (1968), "Long-period waves generated in the polar ionosphere during the onset of magnetic storms", Journal of Geophysical Research. Vol. 73(19), pp. 6319-6336.
Abstract: Large-scale trains of traveling waves observed at Puerto Rico during the onset of three magnetic storms are described. The vertical wave structure is examined between 100 and 800-km altitude with a range resolution of 37.5 km during the day and 75 km at night. The wave period ranges from 2 to 4 hours. Horizontal phase velocity measurements were made during the wave train of highest amplitude. The speed of the first observed cycle was 700 m/sec and that of the last (11 hours later) was 125 m/sec. In both cases the direction of propagation was approximately north to south. The velocity of intermediate cycles could not be determined. Speeds of the order of 125 m/sec are typical for partially ducted gravity waves of long period, and the low speed cycles of the wave train are possibly of this type. Speeds of 700 m/sec, however, are too great to be explained in this way. It is suggested that the high-speed portion of the wave train represents energy propagated in a fully ducted mode that exists along the base of the thermosphere. A simple 2-layer model of the neutral atmosphere is used to compute the vertical structure of such a wave and the corresponding electron concentration perturbation. A quantitative comparison is made with the observations, and good agreement is found. It is concluded that the observed waves are atmospheric gravity waves powered by energy deposited in the auroral atmosphere during magnetic storms.
BibTeX:
@article{Thome1968,
  author = {Thome, George},
  title = {Long-period waves generated in the polar ionosphere during the onset of magnetic storms},
  journal = {Journal of Geophysical Research},
  year = {1968},
  volume = {73},
  number = {19},
  pages = {6319-6336},
  doi = {10.1029/JA073i019p06319}
}
Wand RH and Perkins FW (1968), "Radar Thomson scatter observations of temperature and ion-neutral collision frequency in the E region", Journal of Geophysical Research. Vol. 73(19), pp. 6370-6372.
BibTeX:
@article{Wand1968,
  author = {Wand, R. H. and Perkins, F. W.},
  title = {Radar Thomson scatter observations of temperature and ion-neutral collision frequency in the E region},
  journal = {Journal of Geophysical Research},
  year = {1968},
  volume = {73},
  number = {19},
  pages = {6370-6372},
  doi = {10.1029/JA073i019p06370}
}
Aarons J (1967), "Ionospheric irregularities at Arecibo, Puerto Rico ", Journal of Atmospheric and Terrestrial Physics . Vol. 29(12), pp. 1619-1624.
Abstract: Nighttime observations of radio stars were made at four frequencies in the band 22-38 MHz with the 1000 foot reflector at Arecibo, Puerto Rico. Weak ionospheric irregularities were a consistent feature in the 21.00-04.00 L.M.T. period. Observations were made in the fall of 1964 and the spring of 1965 when the sunspot number was low. The maximum scintillation activity took place at 01.00 L.M.T. The time of maximum is the same as that observed for the maximum occurrence of spread-F during low sunspot number years. By measuring scintillation index as a function of wavelength, it was determined that the irregularity height was close to 300 km. In a related study during this time period, satellite scintillations at 40 MHz were observed. It was shown that the weak ionospheric irregularities at night are uniform over a large range of latitudes. Scintillation indices increase rapidly at sub-auroral and auroral latitudes such as Sagamore Hill, Massachusetts and Thule, Greenland.
BibTeX:
@article{Aarons1967,
  author = {Jules Aarons},
  title = {Ionospheric irregularities at Arecibo, Puerto Rico },
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1967},
  volume = {29},
  number = {12},
  pages = {1619-1624},
  url = {http://www.sciencedirect.com/science/article/pii/0021916967901146},
  doi = {10.1016/0021-9169(67)90114-6}
}
Gordon WE (1967), "F region and magnetosphere, backscatter results", Reviews of Geophysics. Vol. 5(2), pp. 191-205.
Abstract: The F region and the magnetosphere are under regular observation by the incoherent-backscatter radar technique at three stations near 70°W longitude and ranging in magnetic latitude from the equator (Jicamarca, Peru), through 30°N (Arecibo, Puerto Rico), to 55°N (Millstone Hill, Massachusetts), and three other stations: Prince Albert in Canada, Nancay in France, and Malvern in England.The total power backscattered from the electrons in a pulse volume at a particular height is related to the number of electrons in the volume when corrected for two factors, each of which usually does not exceed 2. The corrections provide for the lack of equilibrium in the electron and ion temperatures and for the ratio of the Debye shielding distance to the operating wavelength. The corrections can be deduced from a spectral analysis of the returned signal. Alternately, and particularly in the F region, the electron density is determined by observing the differential Faraday rotation of the polarization of the signal, or, under certain conditions by measuring the weak spectral line at the electronic plasma frequency.The total scattered power can be considered to arise from two components: one component having a frequency spectrum spread around the transmitted frequency in a band corresponding to, and produced by, the electronic thermal motions, and the second component having a frequency spectrum spread around the transmitted frequency in a band corresponding to, and produced by, the ionic thermal motion. For all of the operating observatories, the conditions are such that the ionic component dominates in the F region and lower magnetosphere, and, since ionic thermal motion depends not only on the ion temperature but also on the ion mass, it is possible to identify the dominant ion and the ionic composition where mixtures are present. The ionic thermal motion fixes the characteristic width of the spectrum, but the shape of the central region of the spectrum is largely due to the ratio of the electron to ion temperatures. Hence from spectra at various heights it is possible to deduce electron temperature, ion temperature, and ionic composition all as functions of height.The three stations near 70°W longitude have regular observational programs that have extended over a year or more. Although the results of these programs are not published for all stations, the principal results will be summarized.Electron density profiles show values of 0.5 x 104 at 10,000 cm-3 at 10,000 km (daytime, Jicamarca) and of 5 x 104 and 1 x 104 at 1000 km (daytime and night, Jicamarca). At all stations diurnal patterns are apparent in the height of the maximum of the F2 layer, including rapid changes near sunrise. Ion production and loss rates are inferred for certain times and heights.The ion temperature during the day increases from about 1000 degrees near the F peak to a few thousand degrees at about 800 kilometers and remains isothermal to the limits of the observation (usually less than 1500 km). At night the values are about one-half these values. The electron temperature near the F peak is higher than the ion temperature by a factor that may reach 3 in the daytime but is only slightly above 1 at night. At greater heights the electron and ion temperatures agree.The dominant ion in the F region is O+, changing to H+ at about 1000 km during the day and at about 700 km at night. He+ is observed in the transition region but in amounts of 10% or 20% of the ion content. These observations are made during quiet solar conditions.Traveling ionospheric disturbances having a wave structure have been observed at heights ranging from 150 km to the limit of observation (about 800 km) and are associated with predictable magnetic storms. They are interpreted in terms of gravity waves on the interface of the cool lower F region and warmer magnetosphere.Photoelectrons produced in the sunlit hemisphere contribute a measurable amount of heat at the conjugate point before its local dawn.
BibTeX:
@article{Gordon1967,
  author = {Gordon, Wm. E.},
  title = {F region and magnetosphere, backscatter results},
  journal = {Reviews of Geophysics},
  year = {1967},
  volume = {5},
  number = {2},
  pages = {191-205},
  url = {http://dx.doi.org/10.1029/RG005i002p00191},
  doi = {10.1029/RG005i002p00191}
}
Mahajan K (1967), "10.7 cm-Solar radio flux and ionospheric temperatures", Journal of Atmospheric and Terrestrial Physics . Vol. 29(9), pp. 1153 -1158.
Abstract: Electron and ion temperatures, derived from backscatter spectra, are examined during the current rising phase of solar activity. There is a strong positive correlation between the 10.7 cm-solar radio flux and night-time ion and electron temperatures, the temperature increase being about 3.4K for each unit increase of 1x1e-22 W/m2 per c/s bandwidth in View the S10.7, the 27-day average 10.7 cm-solar flux. The noontime ion temperature at and below 400 km shows an equally strong correlation with the 10.7 cm-flux, the temperature increase being about 4.5K for each unit increase of View theS10.7. Any correlation of the noontime electron temperature, and the noontime ion temperature for heights above 400 km, with the 10.7 cm-solar flux, if present, is masked by the more predominant effect associated with the wide day-to-day electron density variations.
BibTeX:
@article{Mahajan1967,
  author = {K.K. Mahajan},
  title = {10.7 cm-Solar radio flux and ionospheric temperatures},
  journal = {Journal of Atmospheric and Terrestrial Physics },
  year = {1967},
  volume = {29},
  number = {9},
  pages = {1153 -1158},
  url = {http://www.sciencedirect.com/science/article/pii/002191696790147X},
  doi = {10.1016/0021-9169(67)90147-X}
}
Nisbet JS (1967), "Neutral Atmospheric Temperatures from Incoherent Scatter Observations", Journal of the Atmospheric Sciences. Vol. 24, pp. 586-593.
Abstract: A method is described for calculating neutral atmospheric temperatures from the data provided by incoherent scatter sounding of the ionosphere. The basis of the method is the use of the data to solve the thermal continuity equation for the ions. In this way the difference between the ion and neutral temperatures can be determined as a function of the heat flow from the ions to the neutral particles and the neutral particle densities. It is shown that under suitable circumstances the neutral temperatures can be determined quite accurately. The method has at present the unique advantage that temperature fluctuations can be followed continuously throughout a day at one location. Calculated values of neutral temperatures for several days derived front incoherent scatter sounding measurements at Arecibo are presented. It is shown that for the days analysed the time of the diurnal temperature maximum was at 1600±1 hour, the diurnal minimum at 0400±1 hour, and the average day-to-night temperature ratio was 1.36±0.03.
BibTeX:
@article{Nisbet1967,
  author = {John S. Nisbet},
  title = {Neutral Atmospheric Temperatures from Incoherent Scatter Observations},
  journal = {Journal of the Atmospheric Sciences},
  year = {1967},
  volume = {24},
  pages = {586-593},
  url = {http://dx.doi.org/10.1175/1520-0469(1967)024<0586:NATFIS>2.0.CO;2}
}
Carlson HC and Gordon WE (1966), "Radar spectrographic estimates of ionic composition from 225 to 1400 kilometers for solar minimum winter and summer conditions", Journal of Geophysical Research. Vol. 71, pp. 5573-5578. American Geophysical Union.
Abstract: Observed diurnal variations of the ionic composition in the ionosphere over Arecibo are presented in the 225–1400-km altitude range for a typical winter and summer day under solar minimum geomagnetically undisturbed conditions. He+ remains a minor constituent (about 20% or less) for all the times observed. In winter it is found to maximize at about 450–500 km at night and at about twice this altitude in the day; the transition from strongly dominant O+ to strongly dominant H+ takes place in a corresponding region whose extent is about 300 km at night but more like triple this in the day. In summer the transition region is some what higher and thicker. Sunrise and sunset rates of change of composition are greater in summer than winter, and the minimum altitude of the contours of constant composition is shifted from local sunrise in summer to roughly midnight in winter. These seasonal differences are ascribed to the effect of photoelectrons streaming from the magnetically conjugate ionosphere.
BibTeX:
@article{Carlson1966,
  author = {Carlson, H C and Gordon, W E},
  title = {Radar spectrographic estimates of ionic composition from 225 to 1400 kilometers for solar minimum winter and summer conditions},
  journal = {Journal of Geophysical Research},
  publisher = {American Geophysical Union},
  year = {1966},
  volume = {71},
  pages = {5573-5578},
  doi = {10.1029/jz071i023p05573}
}
Carlson HC (1966), "Ionospheric heating by magnetic conjugate-point photoelectrons", Journal of Geophysical Research. Vol. 71(1), pp. 195-199.
Abstract: Regular observations of incoherent backscatter spectrums of the ionosphere at the Arecibo Ionospheric Observatory in Puerto Rico since June 1964 establish presunrise and postsunset ionospheric heating above the Fmax to be present during the winter, though less evident toward either equinox, and absent during the summer. The observed heating is interpreted in terms of a streaming of photoelectrons from the sunlit magnetic conjugate ionosphere. The detailed timing of the onset of the heating supports this, and a semiquantitative model for the heating mechanism explains further details of the observations. Photoelectrons streaming from the magnetic conjugate ionosphere are concluded to produce significant heating effects for the midlatitude upper F region.
BibTeX:
@article{Carlson1966a,
  author = {Carlson, H. C.},
  title = {Ionospheric heating by magnetic conjugate-point photoelectrons},
  journal = {Journal of Geophysical Research},
  year = {1966},
  volume = {71},
  number = {1},
  pages = {195-199},
  url = {http://dx.doi.org/10.1029/JZ071i001p00195},
  doi = {10.1029/JZ071i001p00195}
}
Cole K (1966), "Magnetic storms and associated phenomena", Space Science Reviews. Vol. 5(6), pp. 699-770.
BibTeX:
@article{Cole1966,
  author = {Cole, K.D.},
  title = {Magnetic storms and associated phenomena},
  journal = {Space Science Reviews},
  year = {1966},
  volume = {5},
  number = {6},
  pages = {699-770},
  doi = {10.1007/BF00173103}
}
Thome GD (1964), "Incoherent scatter observations of traveling ionospheric disturbances", Journal of Geophysical Research. Vol. 69(19), pp. 4047-4049.
Abstract: The incoherent scatter technique is used to study large-scale traveling ionospheric disturbances above Puerto Rico. Below the F-region maximum the measurements of disturbance amplitude, period, and direction of phase progression with time (downward) are consistent with the bottomside results of other workers. Above the maximum, however, the surfaces of constant phase are found to become vertical, disturbance amplitude becomes less, and the periods become greater.
BibTeX:
@article{Thome1964,
  author = {Thome, George D.},
  title = {Incoherent scatter observations of traveling ionospheric disturbances},
  journal = {Journal of Geophysical Research},
  year = {1964},
  volume = {69},
  number = {19},
  pages = {4047-4049},
  doi = {10.1029/JZ069i019p04047}
}
Verlag W-V (1964), "Licht als InformationstrÄger bei elektrischen Messungen/Molekular-Siebe/Radioteleskop von Arecibo", Physik Journal. Vol. 20(1), pp. 30-32. WILEY-VCH Verlag GmbH.
BibTeX:
@article{Verlag1964,
  author = {WILEY-VCH Verlag},
  title = {Licht als InformationstrÄger bei elektrischen Messungen/Molekular-Siebe/Radioteleskop von Arecibo},
  journal = {Physik Journal},
  publisher = {WILEY-VCH Verlag GmbH},
  year = {1964},
  volume = {20},
  number = {1},
  pages = {30-32},
  url = {http://dx.doi.org/10.1002/phbl.19640200108},
  doi = {10.1002/phbl.19640200108}
}
Cohen MH (1963), "Hydrodynamic theory of plasma density fluctuations", Journal of Geophysical Research. Vol. 68(20), pp. 5675-5679.
Abstract: The spectrum of electron density fluctuations is computed using a collisionless two-fluid plasma model with isotropic pressure. The major disagreements with kinetic theory are (a) the fluid theory gives sharp lines only, with no Landau broadening, and (b) the gyroresonant structure of the kinetic theory is missing in the fluid theory.
BibTeX:
@article{Cohen1963,
  author = {Cohen, Marshall H.},
  title = {Hydrodynamic theory of plasma density fluctuations},
  journal = {Journal of Geophysical Research},
  year = {1963},
  volume = {68},
  number = {20},
  pages = {5675-5679},
  url = {http://dx.doi.org/10.1029/JZ068i020p05675},
  doi = {10.1029/JZ068i020p05675}
}
Salpeter EE (1963), "Density fluctuations in a nonequilibrium plasma", Journal of Geophysical Research. Vol. 68(5), pp. 1321-1333.
Abstract: A dilute ionized gas is considered, for which electronion collisions can be neglected and which deviates from thermal equilibrium by having an ion temperature T4 different from the electron temperature Te. These conditions apply to the ionosphere in the F layer and above. Methods are reviewed for treating statistical mechanics at thermal equilibrium and the Boltzmann equation for general problems. The electron-electron, electronion, and ion-ion pair correlation functions are derived for general TeT4, and an arbitrary time-independent magnetic field. The total cross section for scattering of an electromagnetic wave from such a gas is derived for general TeT4. The results are shown to agree with the integral of the theoretical frequency spectrum derived previously by a number of authors. For long wavelength and T4Te<<1 the cross section is proportional to T4Te. The sources of error for an incorrect result stated by Renau are explained.
BibTeX:
@article{Salpeter1963,
  author = {Salpeter, E. E.},
  title = {Density fluctuations in a nonequilibrium plasma},
  journal = {Journal of Geophysical Research},
  year = {1963},
  volume = {68},
  number = {5},
  pages = {1321-1333},
  url = {http://dx.doi.org/10.1029/JZ068i005p01321},
  doi = {10.1029/JZ068i005p01321}
}
Cohen MH (1962), "Radiation in a Plasma. II. Equivalent Sources", Physical Review. Vol. 126(2), pp. 389. APS.
Abstract: We postulate that the fields in a plasma satisfy the linearized plasma equations containing electric and acoustic source terms. The fields and discontinuities produced by surface layers of the sources are discussed. It is shown that the fields in a homogeneous source-free volume are given uniquely by their values in V at time zero, plus boundary values for t>0, either nâE or nâH, and either n1 or n.v. The fields in the volume are the same as those radiated by a certain set of equivalent surface sources on the boundary.
BibTeX:
@article{Cohen1962,
  author = {Cohen, Marshall H},
  title = {Radiation in a Plasma. II. Equivalent Sources},
  journal = {Physical Review},
  publisher = {APS},
  year = {1962},
  volume = {126},
  number = {2},
  pages = {389},
  url = {http://link.aps.org/doi/10.1103/PhysRev.126.389},
  doi = {10.1103/PhysRev.126.389}
}
Cohen MH (1961), "Radiation in a Plasma. I. Cerenkov Effect", Physical Review. Vol. 123, pp. 711-721. American Physical Society.
BibTeX:
@article{Cohen1961,
  author = {Cohen, Marshall H.},
  title = {Radiation in a Plasma. I. Cerenkov Effect},
  journal = {Physical Review},
  publisher = {American Physical Society},
  year = {1961},
  volume = {123},
  pages = {711-721},
  url = {http://link.aps.org/doi/10.1103/PhysRev.123.711},
  doi = {10.1103/PhysRev.123.711}
}
Gordon W and LaLonde L (1961), "The design and capabilities of an ionospheric radar probe", IRE Transactions on Antennas and Propagation. Vol. 9(1), pp. 17-22.
Abstract: Staff members of the Cornell University Center for Radiophysics and Space Research have designed an ionospheric radar probe to be located near Arecibo, Puerto Rico. The radar will have the following general specifications: 1) Antenna reflector, 1000-foot-diameter spherical bowl, illuminated by a 430-Mc dual-polarized feed. 2) Transmitter of 2.5 Mw peak, 150 kw average power, or 100 kw CW power. 3) Dual-channel receiver, capable of measuring total power, polarization and received spectrum. The radar will initially be used to measure the variation of electron density with height, the fluctuations of electron density at fixed heights and electron temperatures and magnetic field strengths at various heights. Ionospheric drifts may also be measured. The radar will also he able to obtain echoes from planets, information of the moon's surface and possibly echoes from the sun. Hydromagnetic shocks may also be detected and a study of cislunar ionization can be made. The passive system with the large antenna may be used as an instrument in radio astronomy to observe radio emission from planets and from true stars, and to make a survey of radio sources. With additional facilities, many radio astronomy measurements can be made taking advantage of the large antenna aperture and resulting high resolving power.
BibTeX:
@article{Gordon1961,
  author = {Gordon, W.E. and LaLonde, L.},
  title = {The design and capabilities of an ionospheric radar probe},
  journal = {IRE Transactions on Antennas and Propagation},
  year = {1961},
  volume = {9},
  number = {1},
  pages = {17-22},
  doi = {10.1109/TAP.1961.1144946}
}
Gordon W (1958), "Incoherent Scattering of Radio Waves by Free Electrons with Applications to Space Exploration by Radar", Proceedings of the IRE. Vol. 46(11), pp. 1824-1829.
Abstract: Free electrons in an ionized medium scatter radio waves weakly. Under certain conditions only incoherent scattering exists. A powerful radar can detect the incoherent backscatter from the free electrons in and above the earth's ionosphere. The received signal is spread in frequency by the Doppler shifts associated with the thermal motion of the electrons. On the basis of incoherent backscatter by free electrons a powerful radar, but one whose components are presently within the state of the art, is capable of: 1) measuring electron density and electron temperature as a function of height and time at all levels in the earth's ionosphere and to heights of one or more earth's radii; 2) measuring auroral ionization; 3) detecting transient streams of charged particles coming from outer space; and 4) exploring the existence of a ring current. The instrument is capable of 1) obtaining radar echoes from the sun, Venus, and Mars and possibly from Jupiter and Mercury; and 2) receiving from certain parts of remote space hitherto-undetected sources of radiation at meter wavelengths.
BibTeX:
@article{Gordon1958,
  author = {Gordon, W.E.},
  title = {Incoherent Scattering of Radio Waves by Free Electrons with Applications to Space Exploration by Radar},
  journal = {Proceedings of the IRE},
  year = {1958},
  volume = {46},
  number = {11},
  pages = {1824-1829},
  url = {http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4065300&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4065300},
  doi = {10.1109/JRPROC.1958.286852}
}