Variability of TEC and Ionospheric Irregularities With Phases of Solar Cycle Within EIA Over East and West African Regions

This study investigated the variability of total electron content TEC and ionospheric irregularities measured as Rate of Change in TEC Index ROTI with phases of solar cycle over East and West African regions. We considered ground GPS measurements taken during the solar cycle # 24 (2009 - 2016) from six stations within the Equatorial Ionospheric Anomaly EIA region. The stations were selected such that three stations are in West Africa (Ykro, dip latitude 2.59°; Nklg, dip latitude 3.08°; Bjco, dip latitude 8.05°) and the remaining three in East Africa (Moiu, dip latitude 9.22°; Mal2, dip latitude 10.25°; Mbar, dip latitude 10.8°). We compared the TEC and ionospheric irregularities obtained at the two regions along the African longitudes. Disparity in the observed TEC and ionospheric irregularities in the two regions were further investigated and probable mechanisms responsible of the disparity discussed. The ascending and declining phases of the solar cycle was considered separately and the effect of the change in phase of solar cycle was also investigated on the observed ionospheric irregularities. Longitudinal variability and sunspot cycle dependence of TEC and ionospheric irregularities were ascertained within African region.