Multi-instrumental investigation of the evolution of super equatorial plasma bubbles and their poleward extension in the African-European longitude sector during the October 2024 geomagnetic storm
摘要
The present study investigates the occurrence of post-sunset super Equatorial Plasma Bubbles (EPBs) during the 10–11 October 2024 intense geomagnetic storm (SYM-Hmin = −390 nT) over the African-European longitude sector through multi-instrument observations. Analysis from the GNSS-derived scintillation index (S4) and the Rate of change of the TEC Index (ROTI) indicated that the EPBs initially develop in the dip-equatorial and low-latitude regions across a broad longitude sector during the storm main phase. Subsequently, these EPBs extended significantly in both hemispheres and reached mid-latitude regions. Additionally, notable plasma depletion structures are observed in the Swarm-B satellite-derived electron density profiles. The storm-generated eastward Prompt Penetration Electric Fields (PPEFs), associated with prolonged southward-directed Interplanetary Magnetic Field Bz component (IMF-Bz) play a critical role in the formation of EPBs and their extension to mid-latitudes. These findings are further supported by the significant vertical plasma uplift observed in the ionogram-derived virtual height. Additionally, Swarm-B electron density profiles showed the significant depletions mainly over Central Africa with moderate and minimal disturbances in East and Western Africa, respectively. Additionally, Spatial variability reveals a hemispheric asymmetry, with relatively larger depletion structures observed in the Northern Hemisphere. These variations are likely associated with the storm-time electric fields modulated by neutral winds. The occurrence of EPBs and associated post-sunset ionospheric irregularities are equatorial and low-latitude phenomenon; however, severe space weather conditions can cause their extension to higher latitudes and disrupt trans-ionospheric signals. This study aims to support the development of mitigation strategies for ionospheric irregularities during intense geomagnetic storms, particularly in the equatorial to mid-latitude regions.