Physics of auroral phenomena : proceedings of the 37th Annual seminar, Apatity, 25 - 28 February, 2014 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Изд-во Кольского научного центра РАН, 2014. - 125 с. : ил., табл.

Т. V. Kozelova and В. V. Kozelov As it was shown in [Kozelova and Kozelov, 2013], during this event in the evening sector the first auroral arc appears near northward horizon of Loparskay (64.9° N; 113.6° E) at 17:58 UT. Several weak diffuse azimuthal arcs were observed equatorward of the first arc. These diffuse auroral arcs were slowly moving equatorward. A few small intensifications were observed on these arcs at -18:06 UT (the moment 1 at Fig. 1) and after the moment 18:22 UT (the moment 2). The auroral perturbation moves from the East to the West. At -18:31:50 UT (the moment 4), the brightening began at Loparskay equatorward of Harang discontinuity, and the auroral breakup occurs at 18:34 UT (the moment 5) that is 22.75 MLT. Panels 6 and 7 at Fig. 2 (from top to down) show the H and D components of the magnetic field at ground- based station BRW in the postmidnight sector. One can see first significant auroral electrojet (AEJ) enhancement at ~ 4 MLT at the moment 1. This was a small intensification during the large substorm growth phase. In the interval between the moment 3 and moment 4, the magnetic pulsations with quasi-period of 4 min are observed at BRW, that corresponds to the Bz IMF oscillations (Fig.l). After the moment 5 the AEJ at the postmidnight sector decays (Fig. 2), and at evening sector the AEJ reached the highest value [Kozelova and Kozelov, 2013]. 3. Observations in the post-midnight sector o f the magnetosphere Fig. 2 also presents observations of the THEMIS-E satellite r -8.2 (4 MLT) during this substorm, panels from top to bottom are: 1 - the low energy (from 6 eV to 30 keV) ESA electron spectrum; 2-4 - the magnetic field components; 5 - the high energy (> 32 keV) SST electron spectrum. One can see: a) after the moment 1, simultaneously with the small intensification during large-scale substorm growth phase, small impulses of dipolarization and an increase of the high energy SST electron were observed at r -8.2; b) after the moment 2, a sudden drop of Bz component (‘explosive stretching1) associated with an increase of the high energy electron and a sharp drop of the low energy electron flux (a plasma sheet thinning); c) 2 min after the moment 3, a large dipolarization of the magnetic field occurs and then ends at the moment 5. This dipolarization was associated with increase of the particle fluxes. Fig. 3 presents the next portion of the THEMIS-E data in the same interval as at Fig. 2. In Fig. 3 from top to bottom: 1 - the total magnetic field; 2-4 - three components of the electric field; 5-10 - six components of the ESA (< 32 keV) ion energy density tensor. From Fig. 3 one can see: a) before the moment 2, the ion energy density was nearly isotropic, a sharp drop of the energy density after the moment 2 was associated with the explosive stretching of the magnetic field observed at the THE; b) in the interval between the moment 2 and the moment 4, the electric field intensively fluctuated and the radial component Ex reached the largest values near the moment 3. THEMIS January 6, 2008 17:50 18:00 18:10 18:20 18:30 18:40 UT Figure 2. Observations of THEMIS-E satellite (electrons and magetic field) and ground-based magnetic station BRW. 4. EDIS at the post-midnight magnetosphere In this event after northward turning of IMF, the quick magnetic field line stretching (a plasma sheet thinning) and Energy-Dispersed Ion Structures (EDIS) were observed at the morning sector. EDIS are well known ion signatures in the magnetosphere. These ion structures demonstrate monotonic decrease in energy as a function of either time or decreasing latitude depending on their type. In recent observational studies, EDIS observed in the magnetotail have been directly associated with ionospheric and plasma sheet activities [Elphinstone et al., 1995; Sergeev et al., 2000] and are observed during different substorm phases. They are recognized as the signatures of the impulsive acceleration processes at 11— 27 Re radial distance. Similar ion structures were recorded at the interval (18:24-18:32) UT of 6 January 2008 by the THEMIS-E satellite during the substorm intensification in the post­ midnight magnetosphere. Fig. 4 shows the observed data in this interval, the panels from top to bottom are: 1 - the high energy SST (> 32 keV) ion spectrum; 2 - the low 23