Impact of Weak Solar Wind Fluctuations on Ionospheric Variability in the African Equatorial Region during Geomagnetically Quiet Days at Equinox and Solstice (March and July 2014)

Abstract

This study “Impact of weak solar wind fluctuations on ionospheric variability in the African equatorial region during geomagnetically quiet days at equinox and solstice (March and July 2014)”, analyses the variability of the ionospheric Total Electron Content (TEC) in the African equatorial region, focusing on the impact of minor solar wind fluctuations during geomagnetically quiet periods. Based on GNSS data from four stations (ADIS, BJCO, MBAR, NKLG) for equinox (March 2014) and solstice (July 2014) periods, the analysis systematically compares TEC variations with solar and geomagnetic parameters. The results confirm marked diurnal and seasonal variability, with significantly higher TEC in March (80–105 TECU) than in July (40–60 TECU). The major contribution of the study lies in the distinction between diurnal and nocturnal correlation regimes. During the night (19:00–24:00 UT), in the absence of photo-ionization, very strong and statistically significant correlations (coefficients often exceeding 0.8) are observed between TEC and solar wind speed (), the () component of the interplanetary magnetic field, and the  index. During the day, TEC variability is primarily linked to solar radiation, with solar wind temperature being the most correlated parameter. This study demonstrates that even subtle solar perturbations significantly modulate the African equatorial ionosphere, particularly at night, highlighting the importance of a multi-parameter approach for precise modeling in this region.