Morphology of Ionospheric foF2 And NmF2 over Ilorin during Low Solar Epochs
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Date
2023
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Mountain Top University Journal of Applied Science and Technology (MUJAST
Abstract
The F2 region critical frequency (foF2) and peak electron density (NmF2) morphology was investigated over Ilorin (latitude 8.31°N, longitude 4.34°E) during a Low Solar Epochs (LSE), a station along the equator anomaly trough. Diurnally, foF2 and NmF2 are visibly more prominent during the day than at night with two characteristic peaks: pre-noon and post-noon peaks. The foF2 and NmF2 pre-noon peak magnitude range: (7.7–8.3 MHz) and (7.3–8.6) × 1011 /m-3 respectively is less compared to the foF2 and NmF2 post-noon peak magnitude range: (7.3–9.7 MHz) and (6.7–11.7) × 1011 /m-3 respectively. Seasonally, the highest values were attained during the post-noon peak in the equinoctial months compared to the solstices months, and also, annually, the post-noon peak is higher than the pre-noon peak. The rapid electron drift away from the equator is responsible for the sharp drop in foF2 and NmF2 after sunset in all seasons. Seasonal peaks in foF2 and NmF2 are suspected to be controlled by the enhanced E × B drifts and the onset and turn-off of solar ionization, which is consistent with some earlier results obtained at some stations in the African region during low solar epoch periods.