Physics of auroral phenomena : proceedings of the 39th annual seminar, Apatity, 29 February-4 March, 2016 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2016. - 167 с. : ил., табл.

S.M. Chemiakov carried out in the range of heights from 30 to 240 km. A step of record of data along height from h = 0.5 n km, where n = 1, 2, 3........ 4. Profiles of electron concentration Amplitudes of ordinary and extraordinary waves received during observations are used for calculation of the electron concentration. The two-dimensional picture of the EC distribution on time and height received in the day of the eclipse on 20 March 2015 is given in Fig. 1. The two-dimensional picture allows receiving EC profiles on height for the chosen time (for example, the line 1 on Fig. 1, see also Fig. 2, a) and EC profiles on time for the chosen height (for example, the line 2 on Fig. 1, see also Fig. 2, b). The EC profiles on time for various heights (Fig. 2, b) are used for finding of the delay of the EC minimum relatively the ionization speed minimum. Figure 2. The electron concentration profile on height for the chosen time (a) and the electron concentration profile on time for the chosen height (b) In the early seventies Chimonas and Hines [1970] have assumed that during a solar eclipse the atmospheric gravity waves caused by a supersonic passing of a lunar shadow across the Earth's surface and cooling of the atmosphere because of reduction of sunlight in the field of the shadow have to be observed. In the next years researchers have received confirmation of existence of the effect [Hanuise et al., 1982; Sauli et al., 2007]. In addition, during a solar eclipse other processes of transfer in the ionosphere influence on the EC profiles. Therefore the “classical” behavior of the EC profiles usually could not be seen. It hampers to determine the EC profile minimum and consequently relaxation time for chosen heights. 5. Results o f observations During the solar eclipses on 11 August 1999, on 1 August 2008, on 1 June 2011 and on 20 March 2015 on the facility of partial reflections at the observatory Tumanny [Chemiakov et al., 2016; Tereshchenko et al., 2001, 2009, 2012] observations of reaction of the lower ionosphere to solar eclipses have been made. On the basis of the obtained data experimental profiles of the electron concentration at heights of D-region of the ionosphere were received. Calculation of temporary delays between the maximum of an eclipse and the minimum of an electron concentration profile has allowed defining values of effective recombination coefficients at heights of D-region of the ionosphere. ;jJ eo • Eclipse maximum » Electron concentration minimum Tim e, UT Figure 3. The electron concentration profiles, c , - .. , . ni c the solar eclipse on 20 March 2015 5.1. Eclipse on 20 March 2015 v The 20 March 2015 solar eclipse was the total one. In the place of observation, the solar eclipse was a partial one: the beginning - at 09:15:8 UT, the maximum - at 10:20:06 UT, the end - at 11:23:58 UT; value of the greatest phase of the eclipse was equal to 0.877; Sun height over the horizon at the time of the greatest phase of the eclipse was 20.5°. The geomagnetic situation in the period of the eclipse was weakly disturbed. The two-dimensional picture of the EC distribution for the period of the eclipse is shown in Fig. 1. In Fig. 3 the EC profiles at various heights used for calculation of ERC are shown. The left points in the figure have designated eclipse maximum time, circles - the minimum of the electron concentration profiles. During the analysis of observation data similar figures were drawn for all heights, but because of influence of various factors, including transfer processes, it was not succeeded to receive ERC for the majority of heights. ERC values calculated from the EC profiles received during observations. For this purpose the EC values at the time of the minimum of the electron formation speed function (in Fig.3 the minimum is designated by a point) were 89