Browsing by Author "Àlàgbé, George Atilade"

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    Ionospheric F2-Region Characteristics of Profile Parameters at an Equatorial Station During Low Solar Activity
    (Nigerian Institute of Physics, 2023-12) Johnson, Mayowa James; Olusegun, Emmanuel Ehinlafa; Àlàgbé, George Atilade
    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.
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    Ionospheric NmF2 Morphology and F2-Region Height of Electron Density Response over Ilorin during low solar activity
    (2023-11) Johnson, Mayowa James; Ehinlafa, Olusegun; Àlàgbé, George Atilade; Onanuga, Kehinde
    The F2 region peak electron density (NmF2) morphology and the height of electron density (hmF2) response was investigated over Ilorin (lat. 8.31°N, long. 4.34°E, dip lat. 2.95 o), a station along the equatorial anomaly trough, during Low Solar Activity (LSA). Diurnally, NmF2 and hmF2 are visibly more prominent during the daytime than the nighttime, having two characteristic peaks: pre-noon and post-noon peaks, except in hmF2 that has post-sunset peak during the nighttime. The NmF2 pre-noon peak with a magnitude range: (7.3-8.6) × 10 11 /m-3 is observed around 0800-0900 LT, while hmF2 of magnitude range: (316-353) km is observed around 1000 LT. The NmF2 post-noon peak magnitude range: (6.7-11.7) × 10 11 /m-3 is observed around 1500 and 1800 LT, while hmF2 post-sunset peak magnitude range: (310-392) km is observed around 1800 and 1900 LT during the entire season. In general, the pre-noon peak magnitude is less compared to the post-noon/post-sunset peak magnitude for all seasons. Seasonally, the NmF2 highest magnitudes were reached during the post-noon in the equinoctial months. The hmF2 highest magnitudes during post-sunset peak were observed in solstices, and also, annually, the post-noon/post-sunset peak is higher than the pre-noon peak for all the seasons. The rapid electron drift in hmF2 away from the equator is responsible for the sharp drop in 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.