Mechanism for Sporadic E Enhancement During the May 2024 Geomagnetic Storm: TIEGCM Simulation

Based on 37 ground-based ionosondes and space-based COSMIC-2 radio occultation observations, Qiu and Liu (2025, https://doi.org/10.1029/2025gl115154) recently reported that Es layers were significantly enhanced during the May 2024 super geomagnetic storm. To explain these observations, this study investigates the geographical distribution and temporal evolution of vertical ion convergence (VIC) that is calculated from the neutral winds simulated by the Thermosphere-Ionosphere-Electrodynamics General Circulation Model. The results show that the VIC was significantly enhanced over East Asia-Australia and Pacific sectors within the 40°S–40°N latitude band, and the VIC patterns exhibit a clear “equatorward propagation” feature, which agrees well with previously observed Es layer intensification patterns. By comparing the contributions of zonal and meridional winds to the VIC enhancement, the result shows that the VIC enhancement is primarily driven by the strengthening of westward winds in this event. These studies suggest that the impacts of super geomagnetic storms on the solar-terrestrial environment can extend to the mesosphere and lower thermosphere and affect the behaviors of irregularities in the ionospheric E region.