Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

Siberian meteors: Ionospheric and geomagnetic effects in the lower ionosphere o fhigh latitudes Figure 1. Map of meteor explosion positions and the Tumanny observatory. was established that the body has entered to the atmosphere from the northwest (the azimuth o f 130-140 degrees) with the inclination of 40-50 degrees and the speed about 32 km/s. 3.1. Geomagnetic conditions and ionospheric effects. A meteor flight in the atmosphere of the Earth is followed by various effects. First of all it makes impact on the environment including the geomagnetic field. Influence of explosions of meteoroids on the geomagnetic field was considered by different researchers [Chernogor, 2014]. In our case for consideration of geomagnetic conditions and behavior of reaction of the geomagnetic field during the explosion and after that it was used data of the IMAGE magnetic stations and the Lovozero observatory. The observatory is situated near the Tumanny observatory and at the distance of 3610 km at the place of the Vilyuysk meteor explosion. Geomagnetic conditions during the meteor explosion were disturbed, there was a substorm. On the Fig. 2 it is shown behavior o f IMAGE electrojet indicators which characterize well enough the geomagnetic situation in the auroral zone of our region ( http://space.jmi.fi/image/il_index/) . Red colour shows IE indicator, green one - IU, blue one - IL. The figure shows two days on 4 and 5 March 2014 for to know geomagnetic situation during the explosion and after that. As we can see during the explosion there was a substorm. It continued about till 1 UT on 5 March. After the time there was the quite period when we can consider the reaction of the geomagnetic field on the explosion. On the Fig. 3 (left) the behavior the IMAGE electrojet indicators during the quite period of the geomagnetic field of 5 March is shown. At that period we definitely can see several sections with specific behavior. Beginnings of the sections are designated by red dotted vertical lines and digits before them. The 1st section shows wavelike behavior which can be connected with waveiike disturbances which come to the region of observations. The next sections (2-4) have sharp increasing o f the IE electrojet indicator. Typical periods of natural oscillations of the atmosphere (Brant-Vaisala periods) at the heights of the lower ionosphere are about 5-10 min, depending on the state of the atmosphere. Therefore, in the variations of the amplitudes of ordinary and extraordinary waves, the presence of wave processes with periods longer than the Brant-Vaisala period (from 10 to 80 min, internal gravity waves) was analyzed. Fig. 3 (right) shows the amplitude of the ordinary wave (upper) and its wavelet spectrum. On the figure (right, lower) the D component of the geomagnetic field at the Lovozero observatory is shown. Behavior of the D component is very similar to behavior o f electrojet indicator IE. Periods of waves in ordinary wave amplitude as well as in the D component at the 1st section have similar behavior and differ from other sections (2-4). It can be said that the waves at sections (2-4) have different nature than waves of the 1st section. At the sections (2-4) amplitude has soliton-like appearance. If we suggest that it is a manifestation of the coming disturbances from the meteor explosion so the velocity of the disturbances are: Vi = 230 m/s, \г ~ 140 m/s, V 3 ~ 120 m/s, v 4 « 100 m/s. The 1st section shows two waves with the periods o f 25 and 54 minutes which continues about 3 hours. In the 1st section waves can be considered as typical internal gravity waves which usually come from the place of a meteor explosion. Such velocities (vi) are typical for the thermospheric waves propagation (at the altitude > 85 km). The coming waves of the 2nd- 4* sections can be describe as slow magneto-hydrodynamic waves (MHD-waves). The velocities of the waves are in the range of the types of waves which spreading after explosion in the lower ionosphere [Sorokin, Fedorovich, 1982; Chernogor, 2011; Tereshchenko etal., 2014]. Figure 2. IMAGE electrojet indicators on 4 and 5 March 2014. 105