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.

V. Guineva et al Apatity were identified and the solar wind conditions during these substorms times were verified. Three typical cases were chosen presenting the variety of substorm developments over Apatity: during a magnetic cloud under highly disturbed conditions, during a recurrent stream under disturbed conditions and in non-storm time, under quiet conditions. Observations Case 1: 17.03.2013. On 17.03.2013 a magnetic cloud passed by the Earth. Some solar wind and interplanetary magnetic field (IMF) characteristics by WIND are presented in Fig.l. The straight vertical lines mark the boundaries of Sheath (06-15 UT on 17 March 2013) and MC (15 UT, 17 March - 6 UT, 18 March 2013) on 17-18 March 2013. A geomagnetic storm developed during this time. The Dst index reached -140 nT. Under these highly disturbed conditions, during the main phase of the storm, two consecutive substorms were generated in 18:28 UT and 18:39 UT, 17 March 2013. The time of the substorms is marked by the dotted line in Fig. 1. The substorms generation and fiirther development can be traced out through the magnetic field X-component records of the stations of the longitudinal chain TAR- NAL and by the magnetic field components registered in 2 stations close to Apatity, Loparskaya and Lovozero. The substorms developed during one of the most disturbed periods of the day. They were observed from Apatity. The all-sky camera registered the substorm onset and further development. In Fig. 2, chosen images of the substorm development are shown. The substorm beginning to the South from the station, the polar edge movement to the North, reaching the station zenith (18:32 UT) and surpassing it, the second intensification in 18:39:40 UT also to the South of the station zenith and its travel to North, the bulge expanding in the whole field of view are seen. The world directions are marked in the first image. The universal time is written above each image. н H CQ С Щtz) О N CQ 8 w aj I * о рч wСЛО ' 3 я и^a £иH \ Ь ' а j 1 i SHEATH UK. MC — - i j/w4i ' "F 1 1 j 1 >ЛлЛ “ I i \ - - 1 — " S w ■......1 s— y — ’ [ " . . . r r i \ i ; Vv 1 ^ 4 N 1 ‘■A** ' ' f ■.... i ■ ... ^ 1 i ...... 1 i 2013/03/17 2013/03/18 Figure 1. Solar wind and IMF parameters (BT, Bz, V, Vx, N, T, P) and the SYMN/H index for magnetic cloud on March 17-18, 2013. Boundaries of the magnetic cloud (MC) and front of cloud (Sheath) are shown by blue and red rectangles, respectively. The onset times of substorms according to the all-sky camera in Apatity are marked by vertical dashed lines. Case 2: 29-30 March 2013. During 29-31 March 2013, a recurrent stream (RS) in the solar wind was observed. The CIR region lasted from 3 to 18 UT on 29 March, and the recurrent stream - from 18 UT on 29 March to 14 UT on 31, March 2013. The recurrent stream caused a geomagnetic storm with minimal Dst=-65 nT. The conditions can be considered as disturbed. Three substorms developed during RS: two substorms during the main phase of the storm (in 18:28 UT and 23:08 UT, 29.03.2013, Dst=-45--50 nT) and one - during the recovery phase (in 19:08 UT, 30.03.2013, Dst=-40 nT). In Fig.3 some images from the first substorm development during the main phase of the geomagnetic storm are presented. The auroral oval arcs were lying over Apatity latitudes. Just before the substorm onset in 18:28 UT the arcs were moving to the South. During the expansive phase of the substorm its polar edge moved in S-N direction, reaching zenith in 18:31:10 UT. In 18:31:20 UT the polar edge surpassed zenith location and after 18:32:40 UT the whole field of view was occupied by the auroral bulge forms. The second substorm followed the same behavior. The picture of the third substorm development looked different (Fig. 4). Chosen images of the substorm development in 19:11:20 UT on 30.03.2013 during the recovery phase of the geomagnetic storm associated with RS are shown in Fig. 4. The substorm onset was to the North of Apatity and the expansion of the South part of the substorm bulge is observed from the station. 15