Significant Midlatitude Plasma Density Peaks and Dual-Hemisphere SED During the 10–11 May 2024 Super Geomagnetic Storm

This study investigates midlatitude ionospheric variations during the super geomagnetic storm on 10–11 May 2024, utilizing multi-instrument data from ground-based sources (Global Navigation Satellite Systems receivers and a Fabry–Perot Interferometer) and space-based measurements (Swarm and DMSP). We observed several distinct density gradient structures in the midlatitude ionosphere, with the main findings summarized as follows: (a) Significant zonal plasma density enhancements developed continuously in local dusk across the American-Pacific-Asian longitude sectors around $\pm 40°$ geomagnetic latitude. These midlatitude peaks exhibited a wide longitudinal extension exceeding 150$°$ and a prolonged duration of 12–15 hr during the late main phase and early recovery phase of the storm. (b) Strong storm-enhanced density (SED) was observed in both hemispheres yet with different longitudinal and universal time preferences. In the Northern Hemisphere, significant SED occurred over the American longitude sector during 20:30–22:30 UT on May 10. In the Southern Hemisphere, pronounced SED was observed not only in the American longitudes during 20:30–22:30 UT on May 10 but also in the Australian longitude sector during 02:00–04:00 UT on May 11.