Physics of auroral phenomena : proceedings of the 38th annual seminar, Apatity, 2-6 march, 2015 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Издательство Кольского научного центра РАН, 2015. - 189 с. : ил., табл.

Yu. Yu. Klibanova et al. arrow - the clockwise polarization). The vertical dotted lines indicate the (9.20 - 11.30) MLT area (sector) of the divergence of waves. The polarization is directed: counterclockwise before noon and clockwise - afternoon. At the high-latitude parallels Ф = 67° - 69° and Ф = 56° - 59° polarization is counterclockwise before the sector of pulsations divergence, then there is a change of the direction of the polarization vector rotation. At the mid- latitude parallel Ф = 52°-54° in lx>w latitude* Arc* of pebwton* divrfi>rttc* O ' о о о l a <j> i i о ф э ф a I о t o i _L a о о o , , r 7.0» 9.00 11.00 13.00 15Л0 17.00 Figure 3. Rotation direction of the polarization vector of the geomagnetic field horizontal component (in the plane x, y) the morning, the polarization is counterclockwise in the divergence sector, and afternoon the polarization is clockwise. At low latitudes before noon the polarization is clockwise and afternoon counterclockwise. The spectral analysis of magnetic field oscillations in the solar wind and on the Earth (Fig. 5). In the SW the two peaks of spectral power (according to the satellite АСЕ {X gse = 247 R e , Y qse = 25 R e , Z gse = 18 Re)) are found at frequencies: / = 2.9 mHz and / = 4.7 mHz. All ground stations registered two peaks at the frequencies: / = 2.9 mHz and 4.4 mHz. At stations located within the projection of the magnetopause (L ~ 6.7) the peak with a maximum spectral power is observed at a frequency / = 4.4 mHz. At the low- latitude stations (L ~ 1), there are two peaks with a maximum spectral power at frequencies: / = 2.9 mHz and / = 4 mHz . Discussion On the dayside magnetosphere during Ssc, the arrival of the SW inhomogeneity front excites waves propagating on the magnetopause in both (to dawn and dusk) directions from the area of contact (Fig. 4). Displacement of the pulsations running away sector from the noon meridian is determined by the azimuthal angle of the front, not by the IMF orientation. The sector boundaries are identified from the change of direction of the azimuthal velocity and polarization rotation, as well as the distribution of the pulsation amplitude. At all latitudes the polarization direction changes inside the sector of divergence of pulsations. Such a change in the polarization direction corresponds to the running away of oscillations from both sides of the sector typical for more quiet events [Mishin et al., 2013]. Moreover, the direction of the polarization vector rotation is observed to be: left at high and middle latitudes before noon, and right- at low latitudes. Changing of the polarization vector rotation with latitude is associated with the resonance peak at a frequency / = 4.4 mHz Spectral analysis shows that the geomagnetic pulsations excited by the sharp Ssc front inside the magnetosphere, are not explicitly related to the SW fluctuations. These pulsations are global, their properties are explained by the excitation mechanism at the magnetopause by the storm front, and a sufficiently high frequency value (J = 4.4 mHz), mainly by the close distance from the Earth to the subsolar magnetopause. Running away sector, 6S°- 60°~5So- l 2 4 м щ Н I 1 ' Figure 4. Directions in the plane (x, y) of the SW inhomogeneity front (thick line), the vector of IMF (dotted arrow) and the direction of propagation of geomagnetic pulsations (solid arrows) at high, middle and low latitudes. Conclusions 1. It is shown that pulsations propagate from the dayside to the night through dawn and dusk sides from the boundaries of the (9.20-11.30) MLT pre-noon sector, with the opposite polarization direction. Position of the sector is determined relative to noon by the azimuthal angle of the front. 2. A change in the direction of rotation of the polarization vector of the geomagnetic field horizontal component (in the plane x, y) is reversed at the transition from middle to low/sub-auroral latitudes. 3. Strong compression of the dayside magnetosphere (L = 6.7) resulted in the observation at all latitudes, of a global, non-SW related oscillations, the frequency of which ( f = 4.4 mHz) is increased compared with the weaker fronts. 13