Electric field control on the occurrence of TID's

Abstract

In this paper the effect of electromagnetic drift of the ionospheric plasma on the amplitude of the gravity wave induced traveling ionospheric disturbances (TID's) is studied. For this purpose, by linear perturbation analysis, the detailed calculations of the fractional electron density perturbations have been made with the help of the continuity equation in which the background electromagnetic drift has been incorporated. Our calculations show that the upward lifting of the F layer causes the amplitude of the TID's to increase in the evening hours, which can explain the broad and pronounced evening time maximum that is invariably observed by many workers in the diurnal variation of the number of occurrences of TID's. The other peak in the TID statistics during the postmidnight hours has been attributed to the spatial resonance mechanism of the Whitehead type, in which the electromagnetic drift vector and phase velocity vector of the gravity wave become almost equal. Our calculations can also explain the other experimental results, such as the diurnal variation of electron density perturbations at different latitudes with period, horizontal wavelength, and azimuth of propagation of the gravity waves.