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.

Substorm effects in the polar latitude atmospheric electricfield disturbances a 03 NOV 2004 1® *JT 04 NOV 2004 04.40-04.42 1Л- b 04 SEP 2006 04.10 - 04.12 UT Fig. 2. The global maps o f the high latitude plasma convection during considered morning and evening substorms, presented in Fig.l: a - Nov. 03-04, 2004; b - Sep. 03-04, 2006. One more morning substorm (October 27, 2005) at 00- 01 UT was developed at Scandinavian meridian with the magnitude of -300 nT at the auroral zone. At the polar latitudes (HOR) the magnitude of this substorm reached -60 nT. Several bay-like geomagnetic disturbances were observed at HOR during the following three hours (Fig. 3). 27.10.2005 h o r UT Fig. 3. The Ez variations and the magnetogram (X- component) at obs. Homsund on October 27, 2005. It is clearly seen (Fig. 3) that each negative magnetic deviation, observed at HOR, was accompanied by the simultaneous positive deviations in the atmospheric electric field (Ez) variations at this station. But there was no linear relationship between the Ez values and the geomagnetic disturbance magnitudes. The global map of polar ionosphere convection during the first substorm (00-01 UT) is presented in Fig. 4. As in the previous cases, HOR was located near the center o f the morning convection vortex. The model of the analytical and numerical estimations of the effects of disturbances in the atmospheric electric field, produced by the magnetospheric or ionospheric origin, demonstrated that the variations in Ez can reach about 30% of the undisturbed Ez level [e.g., Volland, 1972; Park, 1976; Zhdanov et a l, 1984; Roble, 1985; Morozov and Troshichev, 2008]. We speculate that the significant variations in the atmospheric electric field (Ez) at Homsund observatory, observed during the development of magnetospheric substorms, are a result of the penetration of the electric fields of polar ionospheric convection (which are intensified during a substorm) to the Earth’s surface. In terms of electric fields the evening Ez negative deviations associated with an increasing o f the northward directed electric field in the ionosphere and the morning positive Ez variations - with ionosphere electric field directed southward. 169