Ionospheric and Magnetospheric Responses to the Extreme Geomagnetic Storm of May 10–12, 2024

Abstract

This paper investigates the global ionospheric and magnetospheric responses to the extreme solar-driven superstorm of May 10–12, 2024. Special focus is placed on the spatiotemporal evolution of storm-enhanced density (SED) plumes, mid-latitude ionospheric troughs, and the intensification of the Equatorial Ionization Anomaly (EIA). Utilizing a multi-instrument framework, we integrate ground-based GNSS observations from IGS networks with in-situ topside plasma measurements from the ESA Swarm satellite constellation. The dates May 10-12, 2024 were specifically selected because they correspond to the occurrence of one of the most intense and historically significant geomagnetic storms of solar cycle 25 according to NOAA. The extreme solar conditions generated strong Magnetosphere-Ionosphere coupling processes, leading to substantial ionospheric disturbances. The results reveal severe, widespread upper-atmospheric disruptions during the storm’s main phase. Peak Total Electron Content (TEC) values exceeded 200 TECU, while the Rate of TEC Index (ROTI) and amplitude scintillation (S4) index surpassed 0.8 TECU/min and 0.9, respectively. The EIA exhibited an intensely enhanced positive storm phase characterized by a profound poleward expansion of the crests. This expansion was driven by a combination of prompt penetration electric fields (PPEFs) and disturbed equatorward thermospheric winds that uplifted the F-layer plasma via enhanced ExB drift. Concurrently, high-rate S4 index measurements captured strong nighttime localized irregularities generated by the rapid growth of plasma bubbles and auroral precipitation. During the recovery phase, mid-latitude regions transitioned into a long-lasting negative ionospheric storm phase, mediated by enhanced chemical recombination and plasma redistribution. These findings characterize the structural dynamics of superstorms during Solar Cycle 25 and provide critical observational constraints for mitigating space weather hazards on global navigation satellite systems (GNSS) and satellite communications. One of our findings shows that, unlike typical geomagnetic storms, an explicit Storm Sudden Commencement (SSC) was apparent during this event.