Physics of auroral phenomena : proceedings of the 39th annual seminar, Apatity, 29 February-4 March, 2016 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2016. - 167 с. : ил., табл.

“P h ysics o f Auroral Phenom ena ”, Proc. XXXIX Annual Sem inar, A patity, pp. 15-18, 2 0 1 6 © Polar Geophysical Institute, 2016 Polar Geophysical Institute DAYTIME POLAR MAGNETIC DISTURBANCES UNDER EXTREMELY STRONG IMF Bz A .E. L ev itin 1, N.G. K leim enova2'3, L.I. G rom ova1, L.A . D rem ukhina1, E.E. A n tonova3’4, N .R . Z elin sky2, S.V . G rom ov1, L.M . M alysheva2 'P u sh ko v Institute o f Terrestrial Magnetism , Ionosphere and Radio Wave P ropagation, Moscow , Russia 2S chm id t Institute o f Physics o f the Earth, Moscow , Russia 3Space R esearch Institute, Moscow , Russia 4Skobeltsyn Institute o f N uclear Physics Lomonosov M oscow State University, Moscow , Russia Abstract. Daytime polar-latitude electrojet, usually termed as PE, has been studied very poorly. We present the results of the detailed analysis of two PE events recorded in the dayside sector of the Earth at the polar geomagnetic latitudes under positive IMF Bz during main phase of the storm on Nov 24, 2001 and recovery phase of the storm of May 30, 2003 Our study was based on the ground high-latitude IMAGE normalyzed magnetogram data. According to model calculations, a sharp intensification of the field aligned currents (FAC) of the NBZ system was noted in that region. The wave structure of this magnetic bay was represented by the (2-7) mHz geomagnetic pulsations which demonstrated the spectral properties different from resonant Pc5 waves. The possible source of high-latitude pulsations could be related with fluctuations in the turbulent magnetosheet. The space distribution of the FAC which can be attributed to NBZ system has been obtained in the polar latitudes by the low-altitude CHAMP satellite. This result has been compared with the auroral oval location (model OVATION) and spectra of the ion and electron fluxes measured by the low-altitude DMSP satellite. We suppose that the daytime polar electrojet under consideration could be mapped inside the closed magnetosphere at poleward part of the plasma ring surrounding the Earth. Introduction. The dayside magnetic bays observed at polar latitudes and controlled by the IMF By sign, are called polar electrojet (PE). Daytime polar-latitude electrojet, usually termed as PE, has been studied very poorly Solar wind-magnetosphere interaction manifests in a magnetic storms occurrence. Solar wind energy storages in the magnetosphere under negative IMF Bz and disappears under positive IMF Bz. It is supposed that development of these dayside substorms, (PE event) that observed in the polar region where the specific system (NBZ) of field- aligned currents, caused by the positive IMF Bz, may be enhanced. Here we study two PE events observed during main phase of the storm on Nov 24, 2001 and recovery phase of the storm of May 30, 2003 as a response of the magnetosphere to high positive values of the IMF Bz occurrence. The observations at the IMAGE Scandinavian magnetometer profile and on the CHAMP and DMSP low orbiting satellites were used for the analysis. This work continues the studies of the high-latitude effects of magnetic storms [Kleimenova et al„ 2015; Levitin et al., 2015], during which considerable positive IMF Bz values are registered. Observations. IMF Bz and By components from high resolution OMNI database) and magnetograms high- latitude of stations for storms of 24 Nov 2001 and for 30 May 2003 are presented in Fig. 1 and Fig. 2 correspondingly. The first PE event was observed during the main phase of the strong magnetic storm on Nov 24, 2001 with Dst m i n -----220 nT (Fig. 1). In this interval the IMF Bz turned northward up to extremely high positive values (~ +60 nT) and the IMF By changed from +40 to -4 0 nT under a high solar wind dynamic pressure up to 50-70 nPa. In the dayside sector of the polar latitudes, the very strong magnetic bay occurred with the amplitude of about 2000 nT. The second PE event was observed in the intensive storm recovery phase on May 30, 2003 with Dst min ~ -144 24.11.2001 Figure 1. The OMNI data ( http://omniweb.gsfc.nasa.gov/ ) and IMAGE magnetograms (http://www.ava.fmi.fi/MIRACLE/) for the storm o f Nov 24, 2001. 15