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.

“Physics o f Auroral Phenomena". Proc. XXXIX Annual Sem inar. A patity, pp. 92-96, 2 0 1 6 © Polar Geophysical Institute, 2016 Polar G eophysical Institute IONOSPHERIC EFFECTS DURING THE TOTAL SOLAR ECLIPSE AT HIGH LATITUDES ON 20 MARCH 2015 S.M . C herniakov, V .A . Tereshchenko, O.F. Ogloblina, E.B . Vasiliev, A.D. Gomonov Po la r G eophysical Institute, Murmansk, Russia e-mail: sergeich@ pgi.ru Abstract. The medium-wave facility of partial reflections of the Polar Geophysical Institute (the observatory “Tumanny”, 69.ON , 35.7E) has observed behavior of the lower high-latitude ionosphere during the 20 March 2015 total solar eclipse. There were several effects during the eclipse. On the height 60-80 km the ionosphere has shown the effect of a “short night”, but at the higher altitudes local enhanced electron concentration regions were revealed and the behavior o f the electron concentration had a wave-like form. The periods and behavior of waves during the eclipse were also calculated using data of the riometer at the obs. “Tumanny”. It can be explained by influence of acoustic-gravity waves which originated after cooling of the atmosphere by the lunar shadow during its supersonic movement along the earth surface and the electron concentration change during the eclipse. 1. Introduction The physical phenomena occurring during solar eclipses in the ionosphere are of interest as conditions of development of eclipses are known and it gives an opportunity to check the existing hypotheses and techniques of researches. Studying of solar eclipses gives useful information for specification of physical processes in the atmosphere and creation of more exact ionospheric models is promoted. Observations of ionospheric effects of solar eclipses have begun right after putting into operation o f vertical sounding stations of the ionosphere [ Schafer, Goodall, 1932]. Early studies considered reaction of the ionosphere to a solar eclipse as the behavior of the environment during a short night. In the early seventies Chimonas and Hines [Chimonas, Hines, 1970] have assumed that during a solar eclipse the atmospheric gravity waves caused by supersonic passing of the 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 similar effect [Sauli et al., 2007]. However it should be noted that the problem of definition of appearance of the acoustic-gravity waves caused by a solar eclipse isn't trivial one as in the ionosphere practically there are always wave processes caused by various sources that can complicate reliable definition o f their appearance. Further researches have shown that physical processes in the ionosphere during solar eclipses are more various and depend on many factors: time of day, season, degree of near-earth space disturbances, etc. All this belongs to the region D, the most difficult and least of all the studied part of the ionosphere [Belikovich, et al., 2003; Tereshchenko, et al., 2011a]. Experimental studies of the region D are complicated because of rather low values o f the electron concentration, complexity and variety of the processes happening at these heights, absence o f sufficient experimental base and difficulties when receiving exact and reliable measurements of sizes which can be used for understanding of the happening processes. The majority of researches of a response to solar eclipses concern behavior of the ionosphere at the heights more than 100 km. Influence of eclipses on the lower ionosphere is investigated much less. The method of partial reflections was applied to studying of reaction of the lower ionosphere to a solar eclipse [ Belrose et al., 1970; Belrose et al., 1972; Benediktov, et al., 1978; Belikovich, Goncharov, 1994]. Interesting data on profiles o f the electron concentration during a solar eclipse were obtained by means of rockets [Kane, 1969; Faire, 1970]. In the work [Haug et al., 1970] results of comparison of simultaneous observations of the partial solar eclipse on May 20, 1966 in Greece by the partial reflections facility and during starts of rockets are considered. Effects of solar eclipses in the equatorial ionosphere where they often occur are rather well studied. Reaction of the ionosphere at the middle latitudes was investigated less as in the region they were more rare. Despite rather simple nature of behavior of the middle-latitude ionosphere, still there is no standard theory of its reaction on solar eclipses. More it belongs to the polar ionosphere where the numerous ionospheric disturbances proceeding in the auroral zone can have a significant effect on the received results. Behavior of the polar ionosphere during solar eclipses was investigated rather seldom [Tereshchenko et al., 2001; Belikovich et al., 2008; Tereshchenko et al., 2011b; Tereshchenko et al., 2012]. Therefore observations of the ionospheric phenomena of solar eclipses by the method of partial reflections in the lower ionosphere of high latitudes are of interest. 2. Equipment and parameters o f the eclipse The partial reflections facility of the Polar Geophysical Institute (PGI) for research of the lower ionosphere consists of the transmitter, the receiver, the transmitting and receiving phased array and the automated system of data 92