Observations and Simulation of Thermospheric Composition Changes During the 14 October 2023 Solar Eclipse

This study presents a full-period imaging of the thermospheric composition response to the 14 October 2023 annular solar eclipse, combining GOLD (Global-scale Observations of the Limb and Disk) far-ultraviolet observations with solar-irradiance-driven WACCM-X (Whole Atmosphere Community Climate Model with thermosphere–ionosphere extension) modeling. GOLD detected up to 80K cooling and >30% airglow reductions in the umbra, with ΣO/N₂ increasing ∼20%. WACCM-X reproduced overall trends but overestimated the ΣO/N₂ increase by ∼5%, underestimated the cooling by ∼60K, and showed slower recovery. The discrepancies between the WACCM-X simulations and the GOLD observations are further corroborated by supplementary TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) observations. The model-data comparison reveals that eclipse-induced thermospheric changes arise from coupled photochemical, dynamical, and radiative processes, providing new insight into the atmospheric response to abrupt solar forcing and refining theoretical models.