The Effects of the Geomagnetic Storm of October 2024 on the African Ionosphere

This study investigates the ionospheric response over the equatorial and low-latitude regions in African during the geomagnetic storm that occurred on 10–11 October 2024. In order to investigate the ionospheric response to geomagnetic storms of varying intensities, a detailed study of vertical Total Electron Content (TEC) variations resulting from Global Navigation Satellite System (GNSS) and International Reference Ionosphere 2020 (IRI2020) data acquired at the Africa sector has been carried out in this work. The data used include GNSS measurements from International GNSS Service (IGS) African eight stations, IRI2020 model, O/N<sub>2</sub> ratio information obtained by the Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI), magnetometer data, and an ionospheric electric fields model. The integrity of GNSS is critically dependent on the state of the Earth’s ionosphere. During space weather events like geomagnetic storms, the ionosphere can become highly disturbed, leading to signal scintillations and severe degradation of navigation reliability. The deviation in TEC was used to observe the ionospheric storm effects. The results show both positive enhancements and negative depletions in TEC across the stations during the events. The findings reveal significant TEC enhancements over the Yamoussoukro (YKRO) and Lusaka (ZAMB) stations, while reductions were observed at the Antananarivo (ABPO), Addis Ababa (ADIS), Djibouti (DJIG), Malindi (MAL2), Mafikeng (MFKG), and N’Koltang (NKLG) stations during the storm’s main phase. During the recovery phase, an increase in TEC was observed at the ADIS and DJIG stations, whereas depletions occurred at the other stations. This study used correlation coefficients (<i>r</i>) and root mean square errors (RMSE) to examine the variation of the IRI-2020 TEC from the Global Positioning System (GPS) TEC during the storm. The results show that the model performs better at some stations (ABPO, MFKG, ZAMB) but underestimates at others (ADIS, DJIG, YKRO). Analysis of the magnetometer data indicates that the H component of the magnetic field experiences a larger disturbance at Keetmanshoop (KMH) than at Hermanus (HER). These results provide crucial insights into storm-time electrodynamics over equatorial and low-latitude regions of Africa and highlight the vulnerability of regional navigation systems.