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Cosmic Research, Vol. 42, No. 5, 2004, pp. 489­534. Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 5, 2004, pp. 509­554. Original Russian Text Copyright © 2004 by Panasyuk, Kuznetsov, Lazutin, Avdyushi, Alexeev, Ammosov, Antonova, Baishev, Belenkaya, Beletsky, Belov, Benghin, Bobrovnikov, Bondarenko, Boyarchuk, Veselovsky, Vyushkova, Gavrilieva, Gaidash, Ginzburg, Denisov, Dmitriev, Zherebtsov, Zeleny, Ivanov-Kholodny, Kalegaev, Kanonidi, Kleimenova, Kozyreva, Kolomiitsev, Krasheninnikov, Krivolutsky, Kropotkin, Kuminov, Leshchenko, Mar 'in, Mitrikas, Mikhalev, Mullayarov, Muravieva, Myagkova, Petrov, Petrukovich, Podorolsky, Pudovkin, Samsonov, Sakharov, Svidsky, Sokolov, Soloviev, Sosnovets, Starkov, Starostin, Tverskay, Teltsov, Troshichev, Tsetlin, Yushkov.

Magnetic Storms in October 2003
Collaboration "Solar Extreme Events in 2003 (SEE-2003)": M. I. Panasyuk1, S. N. Kuznetsov1, L. L. Lazutin1, S. I. Avdyushin2, I. I. Alexeev1, P. P. Ammosov3, A. E. Antonova1, D. G. Baishev3, E. S. Belenkaya1, A. B. Beletsky4, A. V. Belov5, V. V. Benghin6, S. Yu. Bobrovnikov1, V. A. Bondarenko6, K. A. Boyarchuk5, I. S. Veselovsky1, T. Yu. Vyushkova7, G. A. Gavrilieva3, S. P. Gaidash5, E. A. Ginzburg2, Yu. I. Denisov1, A. V. Dmitriev1, G. A. Zherebtsov4, L. M. Zelenyi8, G. S. Ivanov-Kholodny5, V. V. Kalegaev1, Kh. D. Kanonidi5, N. G. Kleimenova9, O. V. Kozyreva9, O. P. Kolomiitsev5, I. A. Krasheninnikov5, A. A. Krivolutsky7, A. P. Kropotkin1, A. A. Kuminov7, L. N. Leshchenko5, B. V. Mar'in1, V. G. Mitrikas6, A. V. Mikhalev4, V. A. Mullayarov3, E. A. Muravieva1, I. N. Myagkova1, V. M. Petrov6, A. A. Petrukovich8, A. N. Podorolsky1, M. I. Pudovkin10, S. N. Samsonov3, Ya. A. Sakharov11, P. M. Svidsky2, V. D. Sokolov3, S. I. Soloviev3, E. N. Sosnovets1, G. V. Starkov11, L. I. Starostin1, L. V. Tverskaya1, M. V. Teltsov1, O. A. Troshichev12, V. V. Tsetlin6, and B. Yu. Yushkov1
3

Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russia 2 Fedorov Institute of Applied Geophysics, Moscow, Russia Shafer Institute of Cosmophysical Research and Aeronomy, Yakutian Scientific Center, Siberian Division, Russian Academy of Sciences, Russia 4 Institute of Solar-Terrestrial Physics, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russia 5 Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN), Troitsk, Russia 6 Institute of Medicobiological Problems, Moscow, Russia 7Central Aerological Observatory, Dolgoprudny, Russia 8 Space Research Institute, Russian Academy of Sciences, Moscow, Russia 9Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia 10 Institute of Physics, University of St. Petersburg, St. Petersburg, Russia 11 Polar Geophysical Institute, Kola Science Center, Russian Academy of Sciences, Apatity, Russia 12 Arctic and Antarctic Institute, St. Petersburg, Russia
Received May 19, 2004

1

Abstract--Preliminary results of an analysis of satellite and ground-based measurements during extremely strong magnetic storms at the end of October 2003 are presented, including some numerical modeling. The geosynchronous satellites Ekspress-A2 and Ekspress-A3, and the low-altitude polar satellites Coronas-F and Meteor-3M carried out measurements of charged particles (electrons, protons, and ions) of solar and magnetospheric origin in a wide energy range. Disturbances of the geomagnetic field caused by extremely high activity on the Sun were studied at more than twenty magnetic stations from Lovozero (Murmansk region) to Tixie (Sakha-Yakutia). Unique data on the dynamics of the ionosphere, riometric absorption, geomagnetic pulsations, and aurora observations at mid-latitudes are obtained.
1

1. INTRODUCTION Active processes on the Sun in the end of October 2003 initiated a series of magnetospheric disturbances whose investigation is of considerable interest for understanding the magnetosphere physics and solving practical problems. At the moment, experimental facilities of our country represent a large complex of ground-based and space instruments which is sufficient for a comprehensive study of the processes of solar­terrestrial activity. This paper presents an attempt to join
Deceased.

1

the efforts of Russian scientific teams in order to investigate the extreme events in October­November 2003. Therefore, the main emphasis in it is made on the comprehension of the results of measurements made by national space vehicles and ground observatories. Magnetic storms cause a variety of processes in the magnetosphere. We consider here the basic processes: deformations of the magnetosphere structure, the boundaries of penetration of solar cosmic rays, boundaries of the auroral zone and polar cap, dynamics of the radiation belts, and the influence of substorms on evolution of the current systems of a magnetic storm. The-

0010-9525/04/4205-0489 © 2004 MAIK "Nauka / Interperiodica"


490 Ap 400 350 300 250 200 150 100 50 0

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Feb. 3 Mar 3 Apr. 3 May 3 June 3 July 3

Aug. 3 Sep. 3 Oct. 3 Nov. 3 Dec. 3

January­December 2003
Fig. 1. Diurnal values of the Ap index of geomagnetic activity in 2003.

ory is represented by model calculations for a given particular series of global storms based on a paraboloidal model of the magnetosphere. The model results are compared with measurements. The integral pattern of a storm is modeled as a time variation of global magnetospheric current systems. These current systems are permanent and exist also in a quiescent magnetosphere. However, during storms the intensity of these current systems increases by more than an order of magnitude under the action of powerful streams of the solar plasma. The spatial structure of the magnetosphere also changes radically. This work represents the first attempt of creating a collaboration of a large group of authors and scientific teams with the aim of a prompt analysis of events that are of exceptional interest for fundamental and applied problems of the space weather. Some nonuniformity of separate sections in dimensions and the style of presentation is inevitable in this case. A certain discrepancy in interpretations of the results of measurements is also inevitable, and we do not press only one version on the reader. Many conclusions are of a preliminary character, the majority of results are presented in a short form, and they will undoubtedly be expanded in subsequent publications. 2. GENERAL CHARACTERISTIC OF MAGNETOSPHERIC ACTIVITY The first paper of our collaboration [1] is devoted to studying the processes on the Sun and in the heliosphere. Here we present a short compilation of solar wind parameters which determine the dynamics of magnetospheric processes in the period under investigation.

As far as geomagnetic activity is concerned, 2003 would become the most disturbed year of the 23rd cycle even without the last burst of the solar activity. All strongest interplanetary and geomagnetic disturbances in 2003 were related to the eruptive activity of the Sun. Throughout the entire year the Earth passed from one high-speed stream of the solar wind caused by a coronal hole into another stream. The magnetic storms produced by high-speed flow of the solar wind from one (the most extended) coronal hole continued for several days and sometimes for more than a week. When sporadic effects were added to the influence of coronal holes, the mean activity of the Earth's magnetic field became extremely high. This is well seen on the plot presenting the behavior of the Ap geomagnetic index in 2003 (Fig. 1). The second maximum of geomagnetic activity is observed, as a rule, on the phase of decline of the solar cycle, but in the current cycle it occurred to be considerably higher than the first maximum. The yearly averaged index Ap of geomagnetic activity is equal to 21.9 nT in 2003. This is an extremely high value which is inferior only to the years 1951, 1960, 1982, and 1991 (Fig. 2). According to preliminary calculations, 62 magnetic storms are detected in 2003. The extremely disturbed periods October 29­31 and November 20 are among them. Three times in the period October 29­30 the maximum possible three-hour Kp index was observed, equal to 9; before this, only one such three-hour interval was recorded in the current cycle (July 2000). The last three days of October turned out to be the most disturbed three-days interval in the entire history of recording the Ap indices. The high magnetic activity is a consequence of extremely high activity on the Sun. The first group of sunspots appeared on the eastern limb on October 17,
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and an extremely rare situation arose on October 29: three huge groups of sunspots were observed on the visible solar disk simultaneously. Then, a series of flares occurred, accompanied by bursts of radio emission and ejections of matter. In this series the flare X17.2/4B beginning at 09:51 UT on October 28 and reaching it maximum at 11:10 UT stands out. It was accompanied by strong radio bursts of all types and by acceleration of charged particles to energies exceeding 7 GeV. A large, dense, and fast ejection of solar mass with a velocity of higher than 2100 km/s was observed during this flare. The interplanetary shock wave (ISW) arrived at the Earth at 06:12 UT on October 29, only in 19 h after the flare. This is the fastest arrival of an interplanetary disturbance since 1972. One more giant proton flare (X10.0/2B, S15W02) occurred in the evening of October 29, with radio bursts of the 2nd and 4th types, high flux of accelerated particles, and bright and fast (the velocity is almost 2000 km/s) mass ejection. As a result of unique combination of the impact of two high-speed streams of the solar wind an extremely large series of magnetic storms came into existence. Unfortunately, the coronal mass ejections (CMEs) which took place during magnetic storms in October 2003 had so extreme parameters that spacecraft-based instruments for measurements of plasma characteristics in the near-Earth space turned out to be unable to work under such conditions. The powerful fluxes of particles caused malfunction in operation of the instruments for plasma measurements onboard almost all spacecraft which performed monitoring of the solar wind (ACE, Geotail, and SOHO). As a result, the data on the velocity and density of the solar wind during the main phase of the magnetic storms of October 28­31, 2003 are fragmentary and contradicting. Nevertheless, the data of these spacecraft presented via the Internet to the disposal of the scientific community allow one to reconstruct the time profile of the solar wind flow in the vicinity of the Earth's magnetosphere. Together with magnetic indices, they are a valuable basis for a detailed analysis of the magnetospheric processes. Figure 3 presents the bulk velocity of the solar wind plasma derived from the spectrum of He++ ions measured by the SWICS instrument onboard the ACE spacecraft dedicated to studying the energy spectra of the solar wind ions. The velocity of the solar wind plasma was determined using the SWICS/ACE data, since the drift velocity of ions in crossed fields does not depend on ion mass and charge. In order to determine the density of the solar wind flow, we have used the data of the Geotail spacecraft (Fig. 4) which on October 28­ 29 was located in the solar wind, upstream of the Earth's bow shock. Extremely powerful manifestations of the solar activity resulted in an extremely strong response of the Earth's magnetosphere, ionosphere, and atmosphere, revealing itself in impressive changes of the state of
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Ap 25 21.9 20 15.1 12.9 10 13.1

15

5

0

2000

2001

2002

2003

Fig. 2. Mean annual values of the Ap index of geomagnetic activity in the period from 2000 to 2003.

V, km/s 2000 ACE/SWICS October 29­30, 2003

1500

1000 1

500

2 0 03 12 18 00 UT
Fig. 3. The velocity of solar wind plasma derived from the spectrum of He++. The data of the SWICS instrument onboard the ACE spacecraft placed at the point of libration. 1 and 2 correspond to the bulk velocity and thermal velocity.

06

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492 , deg V, km/s N, cm­3 100 10 1 800 400 0 180 90 106 105 104

PANASYUK et al. Geotail/CPI-SW October 28­November 1, 2003

T, K

October 28

October 29

October 30

October 31 November 1

Fig. 4. The results of measurements by a plasma analyzer onboard the Geotail spacecraft from October 28 to November 1, 2003. From top to bottom: density, velocity, tilt angles, and temperature of plasma.

plasmas, populations of energetic charged particles, electric currents, and electromagnetic fields. Strongly increased pressure of the solar wind and strong interplanetary magnetic field (IMF) of the geoeffective southern direction sharply changed the structure of the Earth's magnetosphere, pushing apart the boundaries of penetration of solar energetic particles deep into the magnetosphere and decreasing the size of the region, in which the trapped radiation can exist (radiation belts). According to one-minute averaged data of magnetometers of the geosynchronous satellites GOES-10 and GOES-12, the Bz component of the magnetospheric magnetic field in the geosynchronous orbit was subject to strong variations on October 29 and 30, 2003, which indicates to satellite exits into the magnetosheath and magnetotail on the dayside and nightside, respectively (see Fig. 5). The magnetic conditions were extremely disturbed throughout the entire period under consideration. A
Bz, nT 200 100 0 ­ 100 ­ 200

series of strong substorms was observed, which occurred every day, while relatively quiet periods lasted for no more than a few hours. Three magnetic storms (with sudden commencement at 06:12 UT on October 29, 2003; with gradual commencement at 12 UT on the same date; and with gradual commencement at 16­18 UT on October 30, 2003) composed a central aggregate of events which can be represented as the development of a strong magnetic storm in three stages. According to the data of the world data center C2 in Kyoto the value of the AE index reached 4000 nT, which is approximately twice higher than one usually detects during magnetic storms (~1500­2000 nT). A detailed analysis of causes of such a high intensity and of the dynamics of auroral electrojets can be performed later, after getting the refined results of observations of various magnetospheric parameters. However, some conclusions can be made using the available preliminary data. Figure 6 presents the plots of the Bz component of the interplanetary magnetic field in the GSM coordinate system; of the electric field of the solar wind calculated according to the following formula E = V B z + B y /2 + V , where = 4.4 â 10­6 (mV/m)/(km/s)2 (this combination of the solar wind parameters correlates best with the AL index, see [2]); and of the AL index (digitized from a preliminary plot). When calculating the electric field the values of the solar wind velocities presented in Fig. 3 were used. It is the anomalously high velocity of the solar wind giving the main contribution to the electric field strength reaching 40­50 mV/m that, apparently, is the main cause of so high geomagnetic activity. Nevertheless, it should be emphasized that AL variations of such amplitudes are not unique and were detected even during not so strong magnetic storms. For example, on September 25, 1998 under a moderate electric field of the solar wind (about 12 mV/m) the stations of the CANOPUS network of magnetometers detected a deviation of the horizontal component down to values of the
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GOES-10, October 29­30, 2003 Bz GSM

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06

12

18

24

06

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18 UT

Fig. 5. The Bz component of the geomagnetic field as measured onboard the geosynchronous satellite GOES-10 in the period October 28­31, 2003. The arrows directed up and down designate the local noon and midnight, respectively.


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order of ­4000 nT, which was explained, in particular, by specific features of the substorm activity. 3. DYNAMICS OF THE MAGNETOSPHERE Considerable changes in the structure of the magnetosphere are the main process of a magnetic storm, so that to reveal the physical nature of these changes is the main problem of studying global storms. The magnetosphere dynamics is determined both by a primary external action of a shock wave coming from the Sun and by an internal action related, for example, to the amplification of a large-scale electric field of the system "solar wind­magnetosphere." In turn, the internal action on the structure of the magnetosphere can be divided in direct-driven and delayed (after accumulation of energy and its release by way of substorms). An immediate result of these actions is acceleration and precipitation of particles, and other changes in the fluxes of charged particles and in the magnetosphere current systems related to them. There occur also considerable displacements of the boundaries and structures, including those located in the inner magnetosphere and fairly stable in the absence of magnetic storms. They include the approach (mentioned above) of the magnetosphere boundary on the dayside to the Earth, the motion to the Earth of the boundaries of stable trapping and radiation belts, as well as the same motion of the boundaries of quasi-trapping and, respectively, of the zone of active forms of auroras. The processes of internal actions on the magnetosphere dynamics are reflected in ground-based observations of variations and pulsations of the magnetic field, in auroras and ionospheric disturbances. They are considered in this section. In addition, the magnetosphere dynamics is traced by measurements of distributions of energetic particles which do not change the structure of the magnetosphere by themselves, but keep tracking its changes. These measurements will be presented in the fourth section. 3.1. Substorm Activity 3.1.1. Dynamics of the auroral zone. The magnetospheric substorms accompany the global storms being their important component. The relationship of indices of substorm activity with Dst is well known for a long time and was confirmed in many papers. For example, Pudovkin, Zaitseva, and Sizova [3] have demonstrated the existence of a good correlation (without observable delays) between Dst and Dp. Similar results were obtained by some other researchers [4, 5]. This relationship indicated to the important if not decisive role of the asymmetric proton ring current arising due to injection of protons with energies 20­100 keV during substorms of the Earth's night side. At the same time it is suggested by Iyemori [6] that the substorm onset is related with the beginning of decline of the Dst
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50 0

AL, nT

­50 60 40 20 0 0

­ 2000 ­ 4000 00 06 12 18 00 06 12 18 00 UT

Fig. 6. The Bz component of the interplanetary magnetic field in the GSM coordinate system; the electric field of the solar wind calculated from the data of the ACE satellite properly shifted in time according to the satellite distance from the Earth; and preliminary AL index for October 29­ 30, 2003.

variation rather than with its amplification--the result directly opposite to the opinion commonly believed beforehand. These ideas are developed in a paper by Maltsev [7] where it is stated that substorms play no role in the development of magnetic storms. Therefore, to consider the role of substorms in a particular sequence of global storms in October­November 2003 is of great importance. A general idea about the substorm activity is given by magnetometers of the eastern chain of stations: Tixie (TIX), Zyryanka (ZYK), and Yakutsk (YAK) (Fig. 7); and by magnetometers of the western chain: Lovozero (Fig. 8) and Moscow (Fig. 9). Relation to Dst. In the bottom panel of Fig. 7 we present again the plot of the Dst variation as reference plot, in order to emphasize a clear coincidence of the main phases of the magnetic storm in the evening of October 29 and on October 30 with chains of bay-like disturbances. Looking at Fig. 8 we again see here the evidence of coincidence of the substorm activity with a buildup of the current system of magnetic storms. So our observations do not confirm the statements that the active phases of substorms are related to decreasing Dst. The traditional point of view (that ions accelerated in the course of a substorm make the main contribution to the partial ring current at the main phase of a magnetic storm) remains to be preferable. Displacement in latitude. From the ratio of horizontal and vertical components of magnetic field variations one can determine that in most bay-shape disturbances the center of the current system was located to the south of stations of the auroral zone, i.e., the southern boundary of the auroral zone is displaced to the equator. As for the near-pole boundary, i.e., the polar cap boundary, it is displaced not so strongly as the equatorial bound-

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Z, TIX

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D, ZYK

Z, ZYK

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1 2 3 4­6 7­9

10­12 13­15

1

2­5 6­8 9­10

0 ­ 100 D ­ 200 ­ 300 04 08 October 29 12 16 20 0 04 08 UT October 30 12 16 20 0 October 31 04 08
st

Fig. 7. Magnetograms of the eastern chain of stations (ICRA) on October 29­31, 2003. From top to bottom: Tixie (TIX), Zyryanka (ZYK), Yakutsk (YAK), and variations of the Dst index. Rectangles mark the intervals of all-sky survey by a TV camera at Zhygansk station (dark segments correspond to intensification of auroral activity). The figures with arrows 1­15 and 1­10 show the instants when the images of auroras on October 29­30 presented in Fig. 13 were made. COSMIC RESEARCH Vol. 42 No. 5 2004


MAGNETIC STORMS IN OCTOBER 2003 B, nT 1000 Z 0 ­ 1000 ­ 2000 Lovozero ­ 3000 0 12 0 UT
Fig. 8. Magnetogram at the Lovozero station (Polar Geophysical Institute), October 29­31, 2003.

495

X

October 29­31, 2003 12 0 12

B, nT 1000 500 0 ­ 500 ­ 1000 ­ 1500 0 12 0 12 UT 0 October 29­31, 2003 12 0 Z H Moscow

Fig. 9. Magnetogram at the Moscow station (IZMIRAN), October 29­31, 2003.

ary. The activity does not leave the traditional zone of auroras, and even if it leaves, then only for a short time. Both on October 29 and 30 we see (judging from the sign of the vertical component of the magnetic field) that the substorm originates in the south, but sometimes in the process of substorm expansion the activity slips to the pole from Lovozero and Tixie. The riometric bursts of absorption of the auroral type (one on October 29 and several on October 30, 2003) also bear witness that auroral particles were accelerated at the latitude of Tixie (Fig. 10). Only near the maximums of Dst and only for a short time the auroral stations appear inside the polar cap, in particular, in the interval 22­24 UT on October 30. The small amplitude of the magnetic bay at 22 UT in Lovozero and Tixie and the low level of riometric absorption do not mean a real decrease of the substorm power: they are rather a consequence of the exit of auroral stations into the polar cap region. Figure 9 presents a magnetoCOSMIC RESEARCH Vol. 42 No. 5 2004

gram of Moscow station (IZMIRAN) which demonstrates a growth of disturbance amplitude in this time. This displacement of the substorm at 22 UT to the south from the auroral zone coincides with the maximum shift to the Earth of the boundary of penetration of solar cosmic rays (SCR) and of the polar cap boundary, as was measured onboard the Coronas-F satellite (see section 4.1). At 00:15 UT on October 31 a classic substorm of the auroral zone is observed again. The displacement of boundaries was anomalously close to the Earth, and it was not long, less than 2 h. The auroral zone remains wide in this case, i.e., between the zone of stable trapping and the magnetotail there is always a broad region of quasi-trapping. SC on October 29. The storm sudden commencement of type SC+ is illustrated by a magnetogram of the Australian station Alice Spring (Fig. 11). It is known that SC can trigger a substorm in the auroral zone, in particular, if a growth phase is observed and energy is


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0 UT

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Fig. 10. Absorption of space radio noise as measured by a riometer of the Tixie station in the period from October 28 to 31, 2003.

B, nT 200

100

X

Z

October 29, 2003

ASP 0

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Y

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Fig. 11. An SC impulse and the onset of the main phase of the storm on October 29, 2003 at the near-equatorial station Alice Spring.

accumulated in the magnetosphere. In our case a strong substorm develops in the midnight sector, and a strong disturbance is observed both in the auroral zone and in middle latitudes (Fig. 12). Here, it is difficult to separate the substorm effect and the disturbance of the main phase of the storm, further investigations are required. 3.1.2. Mid-latitude substorms and auroras. Figure 13 presents a series of aurora images recorded at Zhigansk observatory (Institute of Cosmophysical Research and Aeronomy, ICRA) in the period from 10:02 UT to 21:14 UT on October 29, 2003 and from 14:35 UT to 19:48 UT on October 30, 2003. The instants of observations are shown by arrows in Fig. 7. The observatory is located near the southern boundary of the auroral zone, and its field of view covers disturbances both in the traditional auroral zone (for example, at 17:55 UT on October 30) and in the subauroral

zone. One can see in Fig. 13 that at 14:33 UT on October 29 a breakup of aurora of classical type was observed at the southern horizon, with a subsequent expansion to the pole (typical for substorms). A sharp commencement of a bay in the H-component was observed at Zyryanka (ZYK) located at the latitude close to that of Zhigansk (60°of corrected geomagnetic latitude), but ~1000 km to the east. Its amplitude was about 1000 nT (and about 600 nT at the magnetometer of the Chokurdakh station). This substorm coincided with the beginning of the main phase of the second magnetic storm, the polar cap boundary and the boundary of penetration of solar protons being located, respectively, near 60° and 53° of corrected geomagnetic latitude. Simultaneously, an enhancement of aurora was detected at the station Maymaga (ICRA). Optical observation area of ICRA, Maymaga station. It is located 150 km to the north from Yakutsk ( =
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63° N, = 129.5° E). Observations were carried out using an infrared digital spectrometer designed to measure the rotational temperatures of molecules of hydroxyl and oxygen at altitudes of 87 and 94 km, respectively. A detailed description of the instrument can be found in [8]. The allowed line OI 844.6 nm of atomic oxygen typical for auroras falls within the recorded spectral region of the spectrograph. The spectrograph operates during the dark time of the day from August to May 15, and its time resolution is 10 min. On October 29 the maximum intensity of this emission reached 12 kRa (absolute calibration was performed by using records of a sensitometric setup with known color temperature). The increased intensity of OI 844.6 nm was recorded for three nights: October 29, 30, and 31. No aurora was observed in other nights, before October 29 and after October 31. In parallel, an all-sky camera operated at Maymaga station. It was used to detect the internal gravitational waves by variations of emission of hydroxyl molecules. Because of a long exposure (150 s) almost all images in the night of October 29 turned out to be overexposed. Figure 14 presents variations of the glow intensity in the 844.6 nm line on October 29, 30, and 31, respectively. Unfortunately, at the instant of SC it was still daylight at the station, and no measurements had been started. The flash of glow at 14:30 UT during the aurora breakup described above is the largest in amplitude at Maymaga and short (less than 10 min, which corresponds to typical duration of the expansion phase of a substorm). Among other observations on October 29, 2003, it is worthwhile to notice that the substorm beginning about 19 UT reveled itself in two bursts (Fig. 14), but in the maximum of the bay the activity sharply escaped to the north, and this strong substorm was not observed at Maymaga. Note also that the mid-latitude magnetometers of the western chain also did not observe this substorm. On October 30 the auroras at Maymaga begin at 18:30 UT, and they give two bright bursts in the interval 19:30­21:10 UT (the same interval when a strong substorm was detected by both western and eastern chains of magnetometers, and when the displacement of the boundary of SCR penetration was observed to be closest to the Earth). Riometric observations at Maymaga confirm that the photometric observations described above belong to events of the substorm class: almost every luminosity enhancement has corresponding burst of riometric absorption of a typical substorm structure which indicates to precipitation of auroral electrons with energies of 10 keV and higher. Note also that in the evening of October 30 a photo of aurora was taken at Troitsk, near Moscow (see the site of IZMIRAN). It is a radiant arc with a red lower side (type B aurora), precisely the type that is usually associated with the active phase of a substorm [9].
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H, nT 1000 SC LOV MCQ

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­ 3000 06

07 UT

08

Fig. 12. Variations of H-components of magnetometers at the observatories Lovozero, Kotelnyi, Leirvogyur, and Mcquery on October 29, 2003 during a substorm triggered by SC.

Geophysical observatory of ISTP SB RAS. The geophysical observatory of ISTP (the Institute of Solar­Terrestrial Physics) of Siberian Branch of Russian Academy of Sciences is located at 52° N and 103° E. Observations were carried out using zenith photometers with interference tilting optical filter (1/2 ~ 1­2 nm) in emission lines 558 and 630 nm. The emissions in the near infrared (720­830 nm) and ultraviolet (360­410 nm) spectral ranges isolated by absorption optical filters were also observed. The angular fields of view were equal to 4°­ 5° for each channel of the photometer. The optical observations on October 29­31, 2003 were carried out under conditions of continuous cloudiness. This circumstance could result in two effects. First, due to absorption by clouds the luminosities of atmospheric emissions detected near the ground surface should be lower than the luminosities at the altitudes where they are emitted. Second, because of largeangle scattering of radiation by the cloudiness the effective field of view of the photometer channels could be of much higher value. Hence, this could lead to detection of the emission from regions with higher latitudes relative to the station location (>1°­2°). In this connection, the absorption of the detected emission by clouds was pr