Seasonal Variations of the Amplitude of the VLF Radio Signals and the Intensity of the Atmospheric Electric Field in Cryolithozone Conditions

Abstract

It is performed an analysis of seasonal variations of the parameters of the underlying surface under cryolithozone conditions far from industrial interference at the SHICRA SB RAS radiophisical polygon near Yakutsk. Seasonal variations of the parameters of atmospheric electricity and the very low frequency (VLF) radio waves propagation from 2009 to 2018 are presented. It is obtained that for summer season the atmospheric electric field near the earth’s surface has a recession due to summer defrosting of the upper layer of permafrost and underlying surface conductivity changes and an increasing of radon output permeability. There is a slight decreasing of amplitude of VLF radio navigation signals received in Yakutsk in summer period. There is an asymmetry in seasonal daytime variations of the VLF signal amplitude. The VLF amplitude during autumn equinox more closely to summer solstice. The asymmetry determined by the season electron density profiles of the ionospheric D region.