Extra Ionization Causing the Anomalous Auroral Sporadic E Layer (Esa) Over the Equatorial Brazilian Region During the Recovery Phase of the Magnetic Storm on 10 May 2024

Abstract The center of the South American Magnetic Anomaly (SAMA), located in southern Brazil, is characterized by enhanced energetic particle precipitation (EPP) at low energies (<40 keV), which can significantly impact the ionosphere during intense geomagnetic storms. Typically confined to high latitudes, sporadic auroral E layers (Esa) have been observed near the SAMA center, particularly during storm recovery phases. However, during the intense geomagnetic storm on 10 May 2024, the Esa layer was detected for the first time over the equatorial Brazilian station Belém (BLM, 1.45°S, 48.49°W, dip = −2.5°). Simultaneously, blanketing Es layers were also observed during the storm's recovery phase, indicating that wind shear mechanisms were also occurring. Satellite data revealed that EPP‐induced ionization extended equatorward beyond the central region of the SAMA, reaching latitudes not previously associated with such effects. Concurrently, disturbed electric fields led to a weakening of the equatorial electrojet (EEJ), inhibiting the development of typical equatorial plasma irregularities. Numerical simulations using the E Region Ionospheric Model confirmed that low‐energy electron precipitation with energy (E) < 2 keV contributed to the observed enhancement in Es layer electron density. These findings provide the first evidence that the occurrence of the Esa layers at equatorial latitudes results from a combination of physical processes, including EPP, wind shear dynamics, and electrodynamic disturbances.