On the plasma density variation in the F2 region during geomagnetic storms

Abstract

The features of ionospheric storm given by the percentage change in frequency (dfoF2) have been investigated for four stations. Using the international quietest days as a reference, dfoF2 was computed as the deviation of the storm day critical frequency from the quiet day diurnal variation. The main interest here was to understand the hemispheric and longitudinal differences in the ionospheric storm responses in these mid latitude locations. Clear hemispheric differences were observed in association of the ionospheric storms with geomagnetic storms. The times of significant ionospheric storms were not usually coincident with peak geomagnetic storms. It is suggested that electrodynamic changes in the high latitudes which could be linked to the geomagnetic storm may be forcing the changes in the sub aurora stations, while localized effect dominate the response in the southern hemisphere stations. These findings have important implications for our present understanding of ionospheric variation in the continent.