Physics of auroral phenomena : proceedings of the 38th annual seminar, Apatity, 2-6 march, 2015 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Издательство Кольского научного центра РАН, 2015. - 189 с. : ил., табл.

1. V. Mingalev and V.S. Mingalev can achieve values of more than 130 m/s at levels of the mesosphere. In the horizontal domains, having a configuration like a limited narrow band, the vertical wind velocity can achieve values of more than 1 m/s at levels of the mesosphere. At these levels, maximal module of the upward vertical wind component is less than the maximal absolute values of the downward vertical wind component. It can be noticed that, from numerous observations, it is known that the global atmospheric circulation can contain sometimes so called circumpolar vortices. In the planetary neutral wind system, these vortices are the largest scale inhomogeneities which are formed at heights of the stratosphere and mesosphere in the periods close to summer and winter solstices. It is known that, in the northern hemisphere, the circumpolar anticyclone arises under summer conditions, whereas, in the southern hemisphere, the circumpolar cyclone arises under winter conditions. Figure 2. The global distributions of the simulated vertical component of the neutral wind velocity at the altitude of 50 km, obtained for 16 July and calculated for three distinct values of geomagnetic activity: Kp=l (top panel), Kp=4 (middle panel), and Kp=7 (bottom panel). The degree of shadowing of the figures indicates the velocity in m/s, with positive direction of the vertical velocity being upward. H“50 km К *7 Longitude Let us compare these observational data with the simulation results, obtained in the present study for July conditions. From the numerically obtained results for summer period in the northern hemisphere, we can see that at levels of the stratosphere and mesosphere, the motion of the neutral gas in the northern hemisphere is primarily westward (Fig. 1), so a circumpolar anticyclone is formed. Simultaneously, the motion of the neutral gas is primarily eastward in the southern hemisphere at levels of the stratosphere and mesosphere (Fig.l), so a circumpolar cyclone is formed for winter period of the southern hemisphere. Thus, the circumpolar vortices of the northern and southern hemispheres, calculated in the present study, correspond well to the global circulation of the stratosphere and mesosphere, obtained from observations for July conditions. Let us consider simulation results, obtained for different values of geomagnetic activity, and their distinctions. It can be seen that the global distributions of the vector of the simulated horizontal component of the neutral wind velocity, calculated for three different values of geomagnetic activity (Kp=l, 4, and 7), are rather distinct. In particular, the maximal absolute values of the horizontal wind velocity, obtained for three different values of geomagnetic activity (Kp=l, 4, and 7), are perceptibly distinct. Incidentally, the lower the value of geomagnetic activity is, the higher the maximal absolute values of the horizontal wind velocity ought to be (Fig. 1). It is clear that the dependence of the global neutral wind system on the geomagnetic activity, obtained in the model calculations at levels of the lower thermosphere, is conditioned by the distinctions of the planetary distributions of the atmospheric temperature, which take place at these levels. From the results shown in Fig. 1, we can see that the global distributions of the vector of the simulated horizontal component of the neutral wind velocity at the altitude of 50 km, calculated for three different values of geomagnetic activity (Kp=l,4, and 7), are perceptibly distinct. This fact can not be explained by the distinctions of the planetary distributions of the atmospheric temperature because of the absence of these distinctions below approximately 80 km, as was noted earlier. Thus, simulation results, obtained for July conditions, indicate that, despite of independence of the 105