Diagnostics of plasmapause by effect of MF radio waves guiding

Active employment of satellites for the study of near-Earth space has revealed much new information. However the space area encompassed by the inner magnetosphere is still not clearly understood. This area in the vicinity of the Earth is coupled with the subauroral ionosphere. The poleward edge of the ionospheric trough is the projection of the plasmapause on the ionosphere and for a steady state it conforms to the boundary of diffuse auroral precipitation (BDP). For the disturbed conditions of winter the plasmapause, its production and dynamics are of primary importance in trough formation. The latitude of the BDP or of the plasmapause projection can be considered as an effective index of geophysical activity. It is being turned to practical use. The instantaneous determination of the BDP location by ground-based measurements allows one predict the propagation of radio waves of different ranges in the subauroral zone over a few hours.