Effect of Ionization Drifts on TID Statistics

Abstract

The effect of electromagnetic drifts of the Ionospheric plasma' on the amplitude of travelling ionospheric disturbances (TIDs) induced by gravity waves is studied. It is found that upward lifting of the F-layer causes the amplitude of the TIDs to increase in the evening hours. The other amplitude enhancement occasionally observed in the morning hours is attributed to spatial resonance mechanism, which is discussed in detail. Theoretical calculations show that horizontal drift rather than vertical drift is more important in controlling the diurnal variation of the TIDs at low latitudes by the spatial resonance mechanism. A reasonable agreement between the theoretical calculations and experimental observations is obtained within the limits of the approximations involved in the calculations.