Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.gao.spb.ru/english/as/j2014/presentations/nastula.pdf Äàòà èçìåíåíèÿ: Sun Sep 28 20:10:38 2014 Äàòà èíäåêñèðîâàíèÿ: Sun Apr 10 01:11:55 2016 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ï ï ï ï ï ï ï ï

Comparison of polar motion excitation functions computed from different sets of gravimetric coefficients

Jolanta Nastula1), Malgorzata Wiska2), Monika Birylo
1) Space Research Center Polish Academy of Science, University of Social Sciences, LÑd, Poland 2) Warsaw University of Technology, Poland 3) University of Warmia and Mazury, Olsztyn, Poland
JournÈes 2014 "SystÈmes de rÈfÈrence spatio-temporels" Recent developments and prospects in ground ­ basedand space astrometry 22-24 September 2014 Pulkovo Observatory, St. Petersburg, Russia

3)


Outline
· Introduction · Data o Gravimetric excitation functions of polar motion. o Geodetic residuals. · Results o Comparison of gravimetric excitation functions with each other. o Examination of the compatibility of these functions with hydrological signal in observed geodetic excitation function. o We focus on subseasonal time scales and seasonal time scales.


Introduction

· Satellite mission Gravity Recovery and Climate Experiment (GRACE) is a source of data on temporal changes in Earth's gravity field. These data are available, in the form of changes in the coefficients Cmn Smn - the so-called Level 2 gravity field product. · These coefficients reflect mainly the impact of the land mass of the hydrosphere on the gravitational field changes. · To a lesser extent, they reflect changes in ice mass, and changes from seismic events. However they do not include information about the influence of the atmosphere and ocean.


Introduction

· There have been a number of attempts to process releases of Gravity Recovery and Climate Experiment (GRACE) data. · Here we use the most recently updated solutions of the GRACE based C21 S21 . · C21 S21 coefficients can be also determined from SLR data analysis. · Recently C21 S21 were redetermined from analysis of observations of CHAMP satellite mission .


Introduction - Excitation functions of polar motion
1 , 2 - components (towards longitudes 0o and 90oE respectively) of gravimetric~hydrological excitation functions are determined from C21, S21 coefficients from the following formulas (Gross, 2013):

2 5 1.098aE M 1 C21 3 C A

2 5 1.098aE M 2 S 3 C A

21

M-mass of the Earth aE-average equatorial radius of the Earth C,A principal moments of inertia


Data used - C21, S21
The following data set were used to estimate the gravimetric excitation functions of polar motion: GRACE monthly solutions: ·AIUB - solution from the Astronomical Institute University of Bern data from July 2003 and December 2009, ·ITG - solution from Institut fÝr GeodÄsie und Geoinformation Bonn, data from August 2002 to August 2009, ·Tongji - monthly solution from the Tongji University, Shanghai, PR China, from January 2003 to December 2010, ·DMT-1 - solution from the Delft Institute of Earth Observation and Space System of the Delft University of Technology, data from February 2003 to February 2009. CSR RL05 - RL05 solution from the Center for Space Research (CSR), 2003 - 2013. ·JPL RL05 - RL05 solution from the Jet Propulsion Laboratory ( JPL), 2003-2013. ·GFZ RL05 ­ RL05 solution from the GeoforschungsZentrum (GFZ) , 20032013 .
available on the website: http://icgem.gfz-potsdam.de/ICGEM/.


Data used - C21, S21
GRACE 10 day solution: ·CNES/GRGS RL02 solution is determined by a combined analysis of the LAGEOS and GRACE observations, January 2003 ­ December 2012. GRACE weekly solution ·GFZ RL05- is a GRACE weekly solution from the GeoforschungsZentrum (GFZ) CHAMP monthly solution ·ULUX - is a monthly solutions from the CHAMP mission observations the University of Luxembourg, January 2003 ­ December 2009. ·All these data are available on the website: http://icgem.gfzpotsdam.de/ICGEM/.
SLR monthly solution ·SLR obtained from the analysis of SLR data to five geodetic satellites: LAGEOS-1 and 2, Starlette, Stella and Ajisai (Cheng and al., 2012).


Data - Excitation Functions of Polar Motion
· In this way we determined 11 series of 1 2 component of gravimetric~hydrological excitation functions of polar motion from the above series of C21, S21

· Next these gravimetric excitation functions of polar motion were compared with so called geodetic residuals (G-A-O) containing the hydrological part of polar motion excitation obtained by removing merged atmospheric (AAM) and oceanic (OAM) excitation from the geodetic excitation function (GAM). · We used the geodetic residuals available on the website IERS--EOP Product Center http:/hpiers.obspm.fr/eop-pc/


Data - Excitation Functions of Polar Motion
· The gravimetric data were given with monthly, weekly and 10 days sampling · The geodetic residuals were given with 6-hour sampling. · All series were smoothed and interpolated with the 30 days or 10 days step in order to harmonize data. · The seasonal 365.25, 180.0 and 120.0-day oscillations and trend were removed from the time series.

· The main purpose was to explore which from these several gravimetric excitation functions are closed to the geodetic observations.


Analysis Non-Seasonal Variations
· Time series · Spectra

· Variances
· Correlation coefficients


Excitation Functions of Polar Motion 1



2

years
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 10 days

1

2

years
Fig. 2 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation. All the data were smoothed with a step of 10 days, FWHM=20. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Spectra G-A-O vs Gravimetric Excitations (30 days)

mas

Period (days)

Fig. 3 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations (10 days)

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 10 days).


Variances Comparison G-A-O vs Gravimetric Excitations (30 days)
Excitation functions G-A-O DMT ITG AIUB Tongji GRACE CSR GRACE GFZ 1 [mas2] Geodetic residuals 28.3 11.9 95.8 179.7 29.9 33.0 6.9 57.1 9.1 104.0 221.7 51.3 60.8 4.6 Gravimetric excitation functions 2 [mas2]

GRACE JPL
SLR ULUX-Champ

166.3
65.8 28.1

211.1
145.5 11.3


Variances Comparison G-A-O vs Gravimetric Excitations (10 days)
Excitation functions G-A-O 1 [mas2] Geodetic residuals 28.3 56.6 2 [mas2]

Gravimetric excitation functions

GFZ
CNES

8.5
121.6

6.4
119.1


Correlation Coefficients G-A-O vs Gravimetric Excitations
Gravimetric excitation DMT ITG AIUB Tongji CSR RL05 GFZ RL05 JPL RL05 SLR ULUX -Champ CNES GFZ
1



2

30 day sampling 0.02 0.24 0.18 0.35 0.24 0.30 0. 0. 0. 10 day 25 10 33 sampling 0.26 0.14 0.15 0.60 0.69 0.37 0.29 0.46 0.01 0.52 0.26

0.30 0.24


G-A-O vs Gravimetric Excitations

1 2 3 4 5 6 7 8 9

DMT ITG AIUB TONGJI CSR GFZ JPL SLR ULUX

DMT ITG AIUB TONG CSR GFZ JPL SLR ULUX GFZ CNES

DMT ITG AIUB TONG CSR GFZ JPL SLR ULUX GFZ CNES

10 GFZ 11 CNES

DMT ITG AIUB TONG CSR GFZ JPL SLR ULUX GFZ CNES

DMT ITG AIUB TONG CSR GFZ JPL SLR ULUX GFZ CNES

Fig. 5 Comparison of gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O.


Annual Oscillations

· Phasor diagrams


Phasor diagrams, annual osciallations
Prograde Retrograde

(mas)

(mas)

Fig. 3 Phasor diagrams of the prograde and retrograde annaul oscillations of the residuals of the geodetic excitation function (G-A-O) and of the different gravimetric excitation functions. Analysis is done over the period 2003.0 to 2009.5.


Conclusions

· We found that gravimetric-hydrological excitation functions, based on the most recent releases, obtained by the several processing centers still differ significantly. · One difference is that a greater degree of smoothness is exhibited by GFZ based functions than the other products. · The best agreement between gravimetric-hydrological excitation functions and geodetic residuals was obtained for the 2 component of gravimetric excitation function computed from the CSR, Tongji and CNES data series, and this may be due to some positive attributes in the processing. · There is some agreement between annual oscillation of G-A-O and of gravimetric excitation based on ITG, GFZ data in the prograde component and between annual oscillation of G-A-O and of gravimetric excitation based on CSR, Tongji, GFZ data in the retrograde component.


Conclusions

· Analyses show that the use of these new data to compare with geodetic residuals does not bring significant new results from to previous studies [Seoane et al. 2009, 2011; Jin et al. 2010,2011, 2012; Chen et al. 2012; Nastula et al. 2011], though confirms the current extent of the differences among the series.


Amplitudes and phases of annual oscillation gravimetric excitations and geodetic residuals
Data Prograde annual Amplitudes Phase [mas] [o] 6.37 1.78 4.16 0.44 10.93 2.75 3.65 4.55 14.49 15.00 3.67 2.59 -53.5 11.7 -60.2 -3.6 -76.6 -2.0 -14.3 -5.8 -53.9 -89.3 -27.5 -170.9 Retrograde annual Ampli Phase tudes [o] [mas] 3.48 120.8 3.98 139.6 8.50 -100.9 2.93 72.0 4.35 -61.3 3.06 138.7 4.50 5.86 14.91 18.35 4.82 3.25 130.2 11.2 128.9 -118.7 137.7 -74.5

G-A-O TONGJI ITG DMT AIUB GRACE CSR RL05 GRACE GFZ RL05 GRACE JPL RL05 ULUX SLR GFZ WEEKLY CNES10


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Excitation Functions of Polar Motion 1



2

years ears
Fig. 1 Comparison of components of the gravimetric excitation functions, 1 and 2, of polar motion from different gravimetric data and of the geodetic residuals G-A-O being the difference between the geodetic excitation function and sum of the atmospheric and oceanic excitation function of polar motion. All the data were smoothed with a step of 30 days, FWHM=60. The 365.25, 180.0 and 120.0-day oscillations were removed from the time series.


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Spectra G-A-O vs Gravimetric Excitations

mas

Period (days)

Fig. 4 FTBPF amplitude spectra of the different complex gravimetric excitation functions of polar motion and of geodetic residuals (G-A-O) (functions smoothed with a step of 30 days).


Phasor diagrams, annual oscillations
Prograde Retrograde

(mas)

(mas)

Fig. 3 Phasor diagrams of the prograde and retrograde annaul oscillations of the residuals of the geodetic excitation function (G-A-O) and of the different gravimetric excitation functions. Analysis is done over the period 2003.0 to 2009.5.


Conclusions

· The fluids around the Earth, atmosphere, ocean, landbased hydrosphere, change their distribution and hence their angular momentum. · Angular momentum exchanges with the solid Earth lead to small but measurable changes in our planet's rotation. They cause changes in the speed of rotation (reckoned in changes in Length-of-day) and the wobble of the Earth, known as polar motion. · The gravity field from satellite-based measurements can help us quantify such changes in mass, needed especially for the hydrosphere, since atmosphere and ocean distributions are reasonably well-known through observations and models.