Longitudinal Variations in the Ionospheric Disturbances: Insights From the May 2024 Super Storm

Abstract

We present an analysis of the super storm event that occurred on 10–11 May, 2024, focusing on ionospheric and magnetic signatures across different longitudinal sectors using space-borne and ground-based data. On 10 May, a strong positive ionospheric storm was observed in the southern hemisphere (winter), while northern hemisphere (summer) experienced negative storm effects. The most pronounced positive storm effects emerged in the American-Pacific sector during local evening hours, followed by Asia and Africa on 11 May. A significant drop in the $O/N_2$ ratio was observed in the northern hemisphere, which likely contributed to the negative ionospheric storm. This depletion appears to be driven by strong thermospheric winds induced by the increase auroral electrojet currents, as indicated by the SME index. The SWARM satellite data revealed numerous plasma bubbles, predominantly at equatorial ionization anomaly (EIA) crests, with some extending up to $40°$ latitude. Our analysis suggests that equatorial plasma bubbles (EPBs) following the initial phase of the storm were enhanced by prompt penetration electric fields (PPEFs) and strong electrojet currents, while those in recovery phase were primarily driven by disturbance dynamo electric fields (DDEFs). Additionally, in the America and Africa regions, the magnitude of $D_{\mathrm{dyn}}$ was higher than in the Asia and Pacific sectors, indicating strong neutral winds that contribute to the decrease in $O/N_2$ ratio. Conversely, $D{P}_2$ exhibited an inverse relation with $D_{\mathrm{dyn}}$, reflecting enhanced solar wind-magnetosphere coupling. This highlights the asymmetric response of different longitudinal regions during this super storm.