%0 Journal Article
%T Daytime variations of foE connected to earthquakes
%A E. V. Liperovskaya
%A V. V. Bogdanov
%A P.-F. Biagi
%A C.-V. Meister
%J Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD)
%D 2011
%I Copernicus Publications
%R 10.5194/nhess-11-1807-2011
%X In the present work it is shown that, in accordance with the observations of the vertical sounding station "Tashkent", the critical foE-frequency of the daytime E-layer increases about one day before winter-earthquakes with magnitudes M > 5 and depths of the epicentre of h < 60 km, which appeared at distances of R < 2000 km from the station. The reliability of the result is larger than 99 %. The phenomenon is not observed for summer-earthquakes. It seems to be determined by the atmospheric wind system. Further, the variations of the foE-frequency are compared with possible simultaneous variations of the critical frequency foF2 of the F2-layer. First results show that only very large changes of the ionisation density in the E-layer influence the ionisation density in the F-region. Therefore, no synchronous growth of the foE- and foF2-frequencies 1¨C2 days before seismic shocks could be observed.
%U http://www.nat-hazards-earth-syst-sci.net/11/1807/2011/nhess-11-1807-2011.pdf