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.

М. V. Klimenko at al. surface to the ionosphere at height of 60 km can exceed more than 250 kV. This large-scale irregularity of ionosphere potential leads to the formation of horizontal electric fields (zonal and meridional electric fields). AEzon, mV/m 24:00 UT AEzon, mV/m 24:00 UT 60 2 3 -30- 30 60 90 120 150 180 210 240 270 300 330 360 Longitude (deg) AEmer, mV/m 24:00 UT Longitude (deg) ДЕтег, mV/m 24:00 UT Longitude (deg) AfoF2, MHz 24:00 UT Longitude (deg) AfoF2, MHz 24:00 UT Longitude (deg) (TECd - TECq)/TECq, 24:00 UT Longitude (deg) (TECd - TECq)/TECq, % 24:00 UT 30 60 90 120 150 180 210 240 270 300 330 360 Longitude (deg) Fig. 2. Calculation results of AEzl 30 60 90 120 150 180 210 240 270 300 330 360 Longitude (deg) AEmer. AfoF2 and ЛТЕС with Therefore in this study we used the numerical experiments with the setting o f conditions o f vertical electric field penetration into the ionosphere above earthquake epicenter area for reproduction of observed changes in the ionosphere prior to the strong high-latitude earthquake on Alaska in 1964. The statement o f a problem and model simulations The calculations were carried out with use of the Global Self-consistent Model o f the Thermosphere, Ionosphere and Protonosphere (GSM TIP) developed in West Department o f IZMIRAN. The model GSM TIP was described in detail by Namgaladze et al. (1988) and modified by Klimenko et al. (2006). The irregularity o f ionosphere potential we can set at height of 175 km (very much above 60 km). Therefore we account the decrease of this potential with height growth. So we consider the irregularity of electric potential in the ionosphere with value o f 10 or 30 kV in the epicenter area at height o f 175 km. We set the irregularity o f electric potential in the ionosphere in spatial grid point above earthquake epicenter and in two nearest grid points in the longitudinal section o f earthquake epicenter, and also in the magneto- conjugated points. These sources of vertical electric field joined and did not change within 24 hours. All calculations were carried out for quiet geomagnetic conditions o f the spring equinox at low solar activity. penetrated vertical electric field at electric potential irregularity, which equals 10 kV (left panel) and 30 kV (right panel). Isolines steps: 0.5 mV/m, 0.2 MHz and 5% (left panel), 1 mV/m, 0.2 MHz and 10% (right panel). Dashed lines - negative values, solid lines - positive values, dotted lines - zero values. Asterisk - earthquake epicenter position. Comparisons of simulation results with experimental data Fig. 1 presents the diurnal variation in critical frequency o f F2-layer, foF2, above station Anchorage obtained in calculation results with electric potential irregularity, which equals 10 and 30 kV, and without seismogenic sources and observed in experiment before earthquake and the same data at the next year. It is visible a good agreement of foF2 disturbances obtained in calculation results and observed in experiment prior to earthquake. Daytime increase in foF2 obtained in calculations at the set of irregularity of the electric potential, which equals 30 kV better agreed with observational data, than at the set of 10 kV. Fig. 2 shows the calculation results of the global disturbances of zonal AEzon and meridional AEmer electric field AfoF2 and global deviations o f total electron content STEC, obtained at 24 UT at the set o f irregularity o f electric potential, which equals 10 kV and 30 kV. In both cases, the formation of local cloud-shape increase in foF2 is visible. The calculation results are in a good agreement with experimental data observed prior to Alaska earthquake with use of Alouette-1 satellite and ionosondes. It is possible to note the better agreement o f calculation results 114