Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

I. V. Mingalev al al. components of the air velocity, the effect of the turbulence on the mean flow is taken into account by using an empirical subgrid-scale parameterization similarly to the global circulation model of the Earth’s atmosphere developed earlier in the PGI [Mingalev I. and Mingalev V, 2005; Mingalev et al., 2007]. Fig.l. The distributions of horizontal component of the air velocity at the altitude of 600 m, assigned at the initial moment (top panel), computed 20 hours after the beginning of calculations (middle panel), and computed 40 hours after the beginning of calculations (bottom panel). The results are obtained for the first initial configuration of the arctic front when, at the initial moment, the modules of the zonal wind velocities at more northern latitudes relatively to the centerline o f the S arctic front are less than those at more southern 1 ll J 6 latitudes relatively to it. The degree of shadowing of the figures indicates the module of the velocity in m/s. Longitude (deg) Thus, the mathematical model is based on numerical solving of non-simplified gas dynamic equations and produces three-dimensional distributions of the wind components, temperature, air density, water vapor density, concentration o f micro drops of water, and concentration of ice particles in the height range from 0 to 15 km over a limited region of the Earth's surface. The dimensions of this region in longitudinal and latitudinal directions are 36° and 25°, respectively. The southern boundary of the simulation region was located at 55° N. The model takes into account heating / cooling of the air due to absorption / emission of infrared radiation, as well as due to phase transitions of water vapor to micro drops of water and ice particles, which play an important role. The finite- difference method and explicit scheme are applied for solving the system of governing equations. The calculated parameters are determined on a uniform grid. The latitude step and longitude step are equal to 0.08°, and height step is equal to 200 m. More complete details of the applied regional mathematical model may be found in the studies of Belotserkovskii et al. [2006, 2009] and Mingalev et al. [201 la]. Simulation results The arctic front separates the cold arctic air masses from warmer air masses. The arctic front can also be defined as the semipermanent, semi-continuous boundary of the cold arctic air mass. As a rule, the extension of the arctic front in the meridional direction does not exceed 200 km and its length in the zonal direction may be more than 2000 km. The direction along which the arctic front passes deviates from the zonal direction, as a rule, is no more than 20 degrees. 194