Dynamics of Proton Flux in the South Atlantic Anomaly During the Super Geomagnetic Storm in May 2024

Abstract

This study presents the short-term dynamic changes in proton flux within the South Atlantic Anomaly (SAA), during a super geomagnetic storm in May 2024. By integrating proton observation data (≥35, ≥70, ≥140 MeV) from multiple National Oceanic and Atmospheric Administration and Meteorological Operational satellite programme satellites with a short-time-scale running average (3-day), we improve spatial resolution and reduce the smoothing effects associated with long-time-scale averaging (∼1 month). The results reveal a rapid (∼20%) decline in proton flux within the SAA region during the main phase of the geomagnetic storm. After reaching its minimum, the proton flux in the SAA rapidly recovered during the recovery phase. Additionally, under the influence of solar proton events, a significant increase in high-energy proton flux was observed during the recovery phase of the storm. Notably, we found a previously unidentified characteristic: a time delay of ∼2.5 days between the minimum proton flux in the SAA and the minimum Dst index (−412 nT).