Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

V. D. Tereshchenko et al. before the main phase of the eclipse for the analysis of data it was used the two-hour period of data received just after that event and 1-minute averaging. It could say that all spectra show similar distribution of fluctuations of all analyzed parameters. Fig. 6. Wavelet-spectra of experimental data during the solar eclipse: a) electron density, Ne, at the height of 87 km; b) heights of reflections of the ordinary wave in the E region, hE, c) Я-component of the geomagnetic field, d) absorption of space radio emission, /„. Fluctuations with the periods from 13 till 20 minutes can be considered as internal gravity waves (IGW) as their period is more than Brunt-Vaisala period for considered conditions. Spectra of the ionospheric parameters at the given time from 20 till 24 UT during the control days do not show such periods of fluctuations. Quasi-periodic disturbances of ionospheric parameters differed, basically, on duration of the prevailing period of fluctuations. These differences from characteristics of the response of the ionosphere on passages of IGW can be explained by dispersive properties of the environment of spreading. 5. Conclusions Thus for the first time ionospheric effects of a solar partial eclipse in conditions of the polar day at big solar zenith angles were investigated. Synchronous decreasing of the electron concentration in 3-4 times at the heights of 85-90 km, increase at the virtual heights of a reflecting layer approximately by 10 km and presence at their temporal courses of wave fluctuations with the periods of 13-20 minutes were shown. Despite of the big solar zenith angles (j = 88° on the terrestrial surface and i = 78-80° at the heights of 70-120 km), effects of the eclipse were shown at all heights in the lower ionosphere and in the geomagnetic field. References Alpert, A. L. (1972), Spreading o f electromagnetic waves and the ionosphere (in Russian), 564 pp., Nauka, Moscow. Boitman, O. N., A. D. Kalikhman, and A. V. Tashchilin (1999), Mid-latitude ionosphere during the total solar eclipse on 9 March 1997: 1. Modeling of eclipse effects (in Russian), Geomagnetism and Aeronomy, 39(6), 45-51. Tereshchenko, V. D., E. B. Vasiljev, N. A. Ovchinnikov and A. A. Popov (2003), Medium wave radar of Polar Geophysical Institute for research of the lower ionosphere (in Russian), in Technical equipment and techniques of geophysical experiment, pp. 37-46, KSC RAS, Apatity. Chimonas, G. (1970), Internal gravity-wave motions induced in the earth's atmosphere by a solar eclipse, J. Geophys Res 75( 28), 5545-5551. Chimonas, G., and C. O. Hines (1970), Atmospherics gravity waves induced by a solar eclipse, J. Geophys. Res., 75(4), 118