Transequatorial V.H.F. Transmissions and Solar-Related Phenomena

Abstract

Radio and ionospheric data are analysed to determine the influences of solargeophysical phenomena on transequatorial v.h.f. transmissions along a EuropeanSouthern African circuit. Results over six years show a close dependence on sunspot number. The observed correlation with sudden ionospheric disturbances indicates periodic solar-dependent defocusing of transequatorial signals by the ionosphere, while the combined effects of neutral winds and the position of the magnetic equator appear to control the seasonal behaviour of the transmissions.