Response of the Ionospheric Electron Temperature Over Sanya to the Super Geomagnetic Storm of May 2024

This study investigated the response of the ionospheric electron temperature (T_e) over Sanya to the super geomagnetic storm of May 2024. The observations, conducted with the Sanya Incoherent Scatter Radar (SYISR; 18.3°N, 109.6°E, dip latitude: 12.8°N) using a zenith-directed uncoded long pulse, provided the T_e from May 10 to 12, 2024. On May 11, the daytime (nighttime) T_e at 400 km increased ∼40% (∼30%) relative to the quiet-time reference, and a wave-like variation of T_e was also observed. On May 12, a unique T_e increase occurred above ∼270 km, with the T_e at 400 km increasing ∼90% relative to the quiet-time reference and remaining increased for ∼7 hr. Further Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations reproduced the observed T_e relatively well under realistic geophysical conditions. The TIEGCM simulations indicated that the decrease in the ionospheric electron density, which was associated with the unique T_e increase, was dominated by chemistry at ∼270–380 km, while E × B drifts and neutral winds contributed most successively at higher altitudes. The simulations also revealed that the relative contribution of the electron-neutral cooling was comparable with that of the electron-ion cooling at 400 km and 09:00 LT on May 12, when the unique T_e increase mainly occurred.