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/N 2 increasing ∼20%. WACCM‐X reproduced overall trends but overestimated the ΣO/N 2 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.