Simulation and Observation of Lunar Tide Effect on High-Latitude, Mesospheric and Lower Thermospheric Winds During the 2013 Sudden Stratospheric Warming Event

We investigate the high-latitude mesospheric and lower thermospheric winds during the 2013 sudden stratospheric warming event using ground-based optical Doppler remote sensing observations of the OH and O (557.7 nm) emission from Eureka (80°N, 86°W) and Thermosphere Ionosphere Mesosphere Electrodynamics-General Circulation Model (TIME-GCM) simulations. Simulations with and without lunar tidal forcing of the TIME-GCM were performed. It has been found that the additional lunar tidal forcing only impacts slightly the semidiurnal tidal amplitude and phase at Eureka. The TIME-GCM simulations still have noticeable discrepancies in the mean winds and the semidiurnal tidal amplitude and phase compared to the observations. The semidiurnal tidal phase shift during the stratospheric warming event may be associated with the sudden stratospheric warming related zonal mean wind reversal, which is similar to the seasonal change in the zonal mean wind from winter to summer. Accordingly, during the reversal, more modes of the semidiurnal tide propagate to the mesosphere, changing the phase of the semidiurnal tide.