Investigation of the Effects of extreme geomagnetic storms of Solar Cycle 25 on the African Equatorial Ionization Anomaly (EIA)

This study investigates the influence of extreme geomagnetic storms of Solar Cycle 25 on the African Equatorial Ionization Anomaly (AEIA) using geomagnetic drivers (Dst and Kp) indices, interplanetary (IMF Bz), solar wind parameters, and Total Electron Content (TEC) observations. Quiet-time conditions were compared with similar ionospheric storm-time variations to evaluate changes in AEIA intensity, crest location, and evolution. Results obtained indicated that during the May 2024 superstorm, extreme storm events, with minimum Dst index values between approximately -220 nT and -412 nT, significantly changed the African EIA. TEC enhancements (45-92%) were observed at the EIA crests, whereas negative storm recovery-phase effects produced TEC reductions (18-57%). Similarly, the EIA crests enhancements (3.1°-6.8°) in latitude were observed with noticeable hemispheric asymmetrical distribution. Additionally, strong EIA intensification during periods of southward IMF Bz coupling below -25 nT and solar wind speed movement enhancements (750-900 km s⁻¹) were noticed, indicating enhanced magnetosphere-ionosphere coupling and equatorial plasma transport interactions. Output of statistical analysis revealed significant periods of storm-time TEC variations compared with periods of quiet conditions (p < 0.01), with variability distribution increasing by 40-70%. Strong correlation distributions were observed between Africa EIA response and geomagnetic drivers, including Dst index (r = 0.74), IMF Bz (r = -0.81), and solar wind speed (r = 0.78). The findings of this study reveal that the extreme geomagnetic storms of Solar Cycle 25, substantially altered African EIA dynamics, highlighting possible impacts on satellite communication, GNSS accuracy, and the need for improved regional space weather forecasting.