The Ionospheric Plasma Density Hole on the 10 May 2024 Mother's Day Great Magnetic Storm

Abstract The ion density and velocity measured by the advanced ionospheric probe (AIP) onboard FORMOSAT‐5 (F5) and ion velocity meter (IVM) onboard FORMOSAT‐7/COSMIC‐2 (F7C2), and the electron density assimilated by the global ionospheric specification (GIS) are employed to study the ionospheric plasma structure and dynamics during the 10 May 2024 Mother's Day storm (Dst −412 nT). The F5/AIP and F7C2/IVM display a large‐scale hole over the magnetic equator in the Atlantic Ocean area (−10° to 25°N, −60° to 20°E) during the local midnight period, with the minimum ion density of 1.7 × 10 4 #/cm 3 and 1.6 × 10 3 #/cm 3 , respectively. In the hole area, F5/AIP and F7C2/IVM reveal upward ion velocities at 720 km altitude and downward ones at 550 km altitude, respectively, while GIS profiles show that the electron density yields the lower peak at ∼440 km and upper peak at ∼760 km altitude. This suggests that the downward and upward ion velocities result in the double‐peak feature.