Ionospheric F2-Region Characteristics of Profile Parameters at an Equatorial Station During Low Solar Activity

Abstract

The ionospheric characteristics of the F2 region critical frequency (foF2), peak electron density (NmF2) and the height of occurrence of electron density (hmF2), was investigated over Ilorin (lat. 8.31°N, long. 4.34°E, dip lat. 2.95o), a station along the equatorial ionization anomaly trough, during a period of low solar activity (LSA). Diurnally, foF2, NmF2 and hmF2 were found to have two characteristic peaks: pre-noon and post-noon peaks, except hmF2 that has post-sunset peak. The foF2 and NmF2 pre-noon peaks occurred around 0800–0900 LT, hmF2’s peak around 1000 LT. The post-noon peaks of foF2 and NmF2 were observed around 1500 and 1800 LT, while hmF2 was observed around 1800 and 1900 LT. In general, the magnitude of the pre-noon peak is less than that of the post-noon/post-sunset peak for all the parameters, for all the seasons. The highest magnitudes of foF2 and NmF2 were reached in the equinoctial months. The rapid faster electron drift in hmF2 away from the equator is responsible for the sharp drop in foF2 and NmF2 after sunset in all seasons. Seasonal peaks in general are suspected to be controlled by the enhanced E × B drifts and, the atmospheric wind, which is consistent with some earlier results obtained at some stations in the African region during low solar activity periods.