Strong Altitudinal Discrepancies in the Evolution of the Southern Storm Enhanced Density and Tongue of Ionization During the Super Geomagnetic Storm on 10 May 2024

This study investigates the three-dimensional evolution of the Storm Enhanced Density (SED) and Tongue of Ionization (TOI) in the Southern Hemisphere during the 10 May 2024 super geomagnetic storm, using the three-dimensional Computerized Ionospheric Tomography (3DCIT) technique. Both SED and TOI structures at 500 km and 800 km exhibited unexpected and contrasting evolutionary trends: between 21:30 and 22:30 UT, they decayed at 500 km but expanded at 800 km. Simulations reveal distinct altitude-dependent transport linked to the SED and TOI. On the dayside, the upward E×B drift lifts plasma to the top ionosphere within the SED region. The poleward drift transported it into the TOI channel, producing the enhanced TOI at 800 km. On the nightside, the equatorward winds transported the plasma upward along the geomagnetic field lines, hence TOI depletion/enhancement at 500/800 km.