Physical Science International Journal

The geomagnetic superstorm of 10 May 2024 produced pronounced ionospheric disturbances whose magnitude and temporal evolution differed across latitudes. This study examined the vertical total electron content (VTEC) response in the 20°E–40°E Europe–Africa sector using observations from seven Global Navigation Satellite System (GNSS) stations spanning northern high latitudes, the equatorial region and southern high latitudes. VTEC and its percentage deviation from a quiet-time reference were analysed over 8–15 May 2024, together with interplanetary and geomagnetic parameters, equatorial electric fields estimated using the Prompt Penetration Equatorial Electric Field Model (PPEFM), and thermospheric O/N₂ maps derived from GUVI observations aboard TIMED. The response varied markedly with latitude, hemisphere and storm phase. Positive VTEC disturbances during the main phase reached approximately +180% at SUTH and exceeded +400% at SYOG. In contrast, negative disturbances reached −63% at VARS, −84% at GLSV and −66% at RAMO, with depletion extending into the recovery phase. At ADIS and MAL2, alternating positive and negative disturbances occurred alongside fluctuations in the interplanetary magnetic field Bz component and PPEFM-estimated equatorial electric fields. Changes in the thermospheric O/N₂ distribution were also observed during the event. Overall, these observations indicate interhemispheric asymmetry and suggest possible contributions from electrodynamic forcing, changes in thermospheric composition and seasonal background circulation. The findings characterise the latitudinal variability of VTEC within the sampled longitude sector.