Investigating Low-latitude Ionospheric Variations During the 2024 "Mother's Day Storm": Combined Swarm and Ground-Based Observations

Geomagnetic storms significantly impact the morphology and dynamics of the Equatorial Ionization Anomaly (EIA). The geomagnetic storm of May 10, 2024, also known as the “Mother’s Day Storm”, was the most intense geomagnetic storm in the last two solar cycles. Given its severity, understanding the storm's impact on the ionosphere is crucial. This study investigates the variations of the low-latitude ionosphere during the Mother's Day Storm, utilizing observations from ESA’s Swarm satellites, as well as total electron density (TEC) estimates from the ground.

Data from the Langmuir Probes, the Electric Field Instrument (EFI), and TEC derived from GPS receivers onboard The Swarm satellites were used to analyze the F-region ionosphere. Additionally, ground-based TEC maps from the Madrigal database were employed to examine the altitudinal evolution of the EIA structure.

Results demonstrate a significant enhancement of the double-peak electron density structure of the EIA during the main phase of the storm (starting around 17 UT on May 10), with evidence of the super fountain effect. The EIA crests reached altitudes above the Swarm B satellite orbit (510 km), extending to approximately 40 degrees north and south of the equator. In contrast, the generation of the EIA was suppressed during the storm's recovery phase. These behaviors are interpreted in the context of storm-induced electric fields.