G. L. Gdalevich

Small-Scale Variations of ELF and VLF Magnetic and Electric Field Components in Subauroral Zone

When “Intercosmos 14” and “Intercosmos 19” satellites passed across the region of inhomogeneities of concentration in the topside ionosphere, which are close to the high latitudinal boundary of the main ionospheric trough, it was found out that there were simultaneous and synchronous fluctuations of plasma concentration Ne, plasma temperature Te and of the amplitudes Hx, Ey of VLF and ELF emissions field components. Probability characteristics of Hx and Ey fluctuations are analyzed. The correlation coefficient RHx,Ey at frequencies less than 4.65 kHz has turned out to be smaller than 0.5; at higher frequencies it increases up to 0.8–0.9. The interpretation of this and similar facts is this: 1) At frequencies less than FLHR a noticeable role belongs to electrostatic waves (drifting or gradient-drifting) which are locally excited. The electrostatic wave have no genetic relation with the electromagnetic ones arrive to the place of registrations from remote regions. 2) At F more than FLHR electromagnetic waves undergoing the influence of the Ne inhomogeneities are recorded. These assumptions explain satisfactorily the phenomena observed.