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.

Magnetospheric and thermospheric origin electricfields influence on the enhanced electron density regions in the night-time ionospheric F2- layer 2. Thermospheric (dynamo) electric field influence on the EEDR’s To investigate the thermospheric (dynamo origin) electric field influence on the equatorial sides of the EEDR’s under different seasons and solar activity levels, the global distributions of nc have been calculated by using the following versions of the UAM: 1) with the theoretically calculated thermosphere parameters (UAM-TT); 2) with the empirical thermospheric NRLMSISE-00 model (UAM-MSIS); 3) with the NRLMSISE-00 and the empirical model of the horizontal neutral wind HWM-93 [Hedin et a l, 1996] (UAM-MSIS-HWM). These versions of the UAM differ by the method of the thermosphere wind velocity and neutral gas IRI-2001 MLT(hours) Figure 3. At first and second raws - the calculated by the IRI-2001 and all UAM versions distributions of Lg(NmF2) maps, at third row - the corresponding geomagnetic latitude-longitude distributions o f the eastward electric field at the altitude 175 km for 18:00 UT 23.06.1986. The black broken curves indicate the summer type of the EEDR’s. The pointers indicate the winter type of the EEDR’s. Lg(NmF2, n r 3) solstice 10.80 11,30 11,80 23.06.1986. № 1 8 :0 0 Eastward electric field (mV/m), h= -3,2 0 3,2 UAM-TT 175 km UAM-MSIS-HWM UAM-MSIS UAM-MSIS-HWM composition calculations. In the UAM-TT version the thermospheric composition and circulation are calculated by the numerical integration o f the continuity, momentum and heat balance equations for the neutral atmosphere. In the UAM-MSIS version composition and three-dimensional circulation of the neutral gas are calculated by using the MSIS model. In the UAM-MSIS-HAM version neutral atmospheric composition is calculated by using the MSIS model and the horizontal neutral wind velocities are calculated by using the HWM. The vertical component of the thermospheric wind velocity is calculated by numerical solution of the continuity equation for the neutral mass density. The model calculations were carried out for eight selected quiet days representing four seasons under the low and high solar activity. The results of the NmF2 calculations were compared with data of the empirical ionospheric model IRI-2001 [Bilitza D , 2001]. The calculated geomagnetic latitude-longitude distributions of NmF2 in the night longitudinal sector (18:00-06:00 MLT) corresponding to solstice (23.06.1986) under the low solar activity are presented in Fig. 3 (first and second rows of the maps). The format of the map presentation is such as preceding ones. Earlier, we showed that two types o f the EEDR’s exist in the latitude-longitude distribution of the NmF2: 1) the summer type, when the electron density isolines have the form of a “ridge with decreasing altitude” (by the “altitude” we understand the values of NmF2) and 2) the winter type, when the closed isolines have the form of a “hill” [Knyazeva, 2009]. Both types of the EEDR’s are clearly visible at all maps in Fig. 2 (the summer conditions -in the northern 119