Simulated variability of the high‐latitude thermosphere induced by small‐scale gravity waves during a sudden stratospheric warming

Abstract

We present the results of the first investigation of the influence of small‐scale gravity waves (GWs) originating in the lower atmosphere on the variability of the high‐latitude thermosphere during a sudden stratospheric warming (SSW). We use a general circulation model that incorporates the spectral GW parameterization of Yiğit et al. (2008). During the warming, the GW penetration into the thermosphere and resulting momentum deposition rates increase by up to a factor of 3–6 in the high‐latitude thermosphere. The associated temporal variability of GW dynamical effects at ~250 km are enhanced by up to a factor of ~10, exhibiting complex geographical variations. The peak magnitude of the GW drag temporal variability locally exceeds the mean GW drag by more than a factor of 2. The small‐scale thermospheric wind variability is larger when GW propagation into the thermosphere is allowed compared to the case when thermospheric GW effects are absent. These results suggest that GW‐induced variations during SSWs constitute a significant source of high‐latitude thermospheric variability.