Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

Geomagnetic and ionosphere TEC response to the abrupt increase o fsolar wind density 2. Interplanetary shock on Jan. 12, 2012. The arrival of IP shock at -1500 UT is revealed according to the OMNI database as a rapid jump of the solar wind velocity V from -400 km/s up to -700 km/s, the interplanetary magnetic field (IMF) magnitude В increase from -3 nT up to -30 nT, and the solar wind density N jump up to 15 cm' 3 (Fig. 1). The shock impact occurs at the background of northward IMF Bz. This shock causes a jump of Dst index and a short impulsive increase of AE index up to -800 nT. After that AE index has remained at elevated level. 3. Geomagnetic response on the ground to SC. We analyze data from latitudinal and longitudinal networks of magnetic stations. During SC the noon meridian is near the Eastern coast of Canada, and CARISMA array is in the morning sector. In morning hours (8.5 MLT) negative PI preceding positive MI is observed at very high geomagnetic latitudes only, Ф>72° (Fig. 2). At lower latitudes (below - 68 °) only positive MI is recorded. In this LT sector MI triggers quasi-monochromatic slowly decaying Psc4-5 pulsations at various latitudes, with periods from T ~5 min at Ф-720 (RANK) to Г-1.5 min at Ф~58°-60° (PINA, THRF). The lack of oscillatory response at Ф~ 66 ° (GILL) probably corresponds to the plasmapausc position. The SC triggers the development of moderate substorm, e.g. magnetic bay at PBK with amplitude up to -500 nT (not shown), though IMF Bz remains northward before and after the shock. In a greatest detail we analyze the multi- instrument data from the dusk sector (Scandinavia) (Fig. 3). The IMAGE magnetometers (LT-17) record "classical" SC: positive MI and preceding it negative PI at 1504 UT (Fig. 3). At a latitude about 67° PI changes its polarity from negative (TRO) to positive (NOR), whereas MI changes polarity between 68°-74°. This polarity reversal of geomagnetic disturbance is commonly interpreted as an evidence of vortex-like structure of the ionospheric currents associated with PI and MI. At latitudes ~65°-67° (NOR, IVA, TRO, SOD) fast-decaying transient Psc5 pulsations with T~5-6 min are excited (Fig. 3). A quasi-period of these pulsations is latitude dependent, so they cannot be associated with cavity oscillations. Their waveforms differ considerably from the Psc4-5 pulsations on the morning flank (Fig. 2). Thus, oscillatory responses of the magnetosphere on the IP shock at the morning and evening flanks are independent. Detailed examination o f PI at stations IVA - SOD - OUL - HAN, covering latitudes from -59° to -65° (Fig. 3), reveals its apparent poleward propagation. This effect may be interpreted as a delay o f the Alfven pulse propagation time from an excitation region in the equatorial magnetosphere towards the ionosphere along different field lines with latitude-dependent Alfven period Tд(Ф). A peak of MI also demonstrates poleward propagation, but with an apparent velocity even larger than that of PI. 4. Ionospheric TEC response to SC as observed by GPS system. We have examined the TEC response from GPS 30-s data downloaded from the IGS website. The TEC data have been converted into the vertical vTEC. The TEC response in the morning hours (Canadian sector) is shown in Fig. 4. The TEC data derived from signals from different GPS satellites received at station CHUR demonstrate a gradual vTEC growth started after SC. These variations are possibly the result of prompt electric field penetration during the main phase of the storm. This TEC growth during SC in the morning sector (Canada) is observed at latitudes above 60° only. The ДТЕС/ТЕС reaches the value 30-40%. UT Figure 1. The interplanetary shock detected on Jan. 24, 2012 during time interval 1400-1900 UT: the OMNI solar wind velocity (Vx component), solar wind density N, IMF magnetic field magnitude В and component Bz, SYM-H index, and AE index. 101