Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

N.G. Kleimenova at al. = 67°; and SOD, Ф = 64°). The geomagnetic midnight at this meridian is near 21 UT. The Ez variations are given in the relative units. One can see that on November 3, 2004 (Fig. la), the intense magnetic substorm developing at the auroral zone (SOD, SOR), was accompanied by the considerable negative Ez anomaly (decreases) at Homsund at -20 -22 UT. At -04 -08 UT on the following day (November 4, 2004), the polar substorm, was observed at polar latitudes (NAL, HOR) and it was absent in the auroral zone. The preliminary phase of this substorm was accompanied by the considerable positive Ez deviations at Homsund. The similar positive Ez variations were observed on September 4, 2006 (Fig. lb) during the morning substorm. The late evening substorm was observed on this day at ~ 19-20 UT and it was accompanied by the negative Ez deviations. Such Ez variations, associated with the morning and evening substorms, were typical for all considered events. The morning substorms were accompanied by the positive Ez deviations and the evening and night­ time substorms - by the negative ones. 3. Discussion It is well known that the coupling between the solar wind and the magnetosphere creates the large scale ionosphere electric field convection. The large-scale pattern of plasma circulation most often conforms to a two-cell configuration with antisunward flow across the pole returning to the dayside via the dawn and dusk flanks. The centers o f the convection cells usually locate poleward of 70 ° latitude with the positive cell at the morning side and the negative cell - at the evening side. A convective motion o f plasma in the geomagnetic field is equivalent to the existence of a horizontal electric field, directed from the morning side to the evening side, in the polar cap. At the poleward boundary of the auroral oval, the field direction reverses. Thus, the auroral electric field is directed toward and from the pole in the evening and morning sectors, respectively. The processing of the data obtained by the system of the northern SuperDARN radars provides to get the maps o f the global convection pattern (available at http://superdam.jhuapl.edu/) . These maps represent the distribution o f the ionosphere electrostatic potential. The polar cap potential variations can produce significant vertical electric fields (Ez) disturbances at the ground level. The global maps of the polar ionospheric convection distribution during two considered above events (Fig. 1) are shown in Fig.2. One can see that on November 3, 2004 at 19.00 UT, HOR was projected inside of the negative convection sell (Fig. 2a, upper panel). However, in the morning on November 4, 2004 (04.40 UT), HOR was projected inside of the positive convection sell (Fig 2a, bottom panel). The same is seen in the second event on September 4, 2006. During the morning substorn (04.10 UT) obs. Homsund was located in the positivt convection sell projection (Fig. 2b, upper panel), but ir the evening - in the negative one (Fig 2b, botton panel). a 03-04.11.2004 UT b 03-04.09.2006 Fig. 1. Two examples o f negative Ez variation: during the night substorms and positive E; variations during the morning substorms: a - Nov 03-04, 2004; b - Sep. 03-04, 2006. 1 6 8