Midnight temperature maximum (MTM) in Whole Atmosphere Model (WAM) simulations

摘要: [1] Discovered almost four decades ago, the midnight temperature maximum (MTM) with typical magnitudes of 50–100 K has been regularly observed by satellite and ground-based instruments in tropical upper thermosphere. Although several mechanisms have suggested to explain phenomenon, previous attempts reproduce it comprehensive thermosphere-ionosphere models unsuccessful. First long-term simulations Whole Atmosphere Model (WAM) reveal presence a realistically prominent MTM salient features its daily, seasonal, latitudinal variability. Preliminary analysis indicates that feature may be traced down lower thermosphere, where is manifested primarily form an upward propagating terdiurnal tidal wave. Its spectrum expands higher-order zonal wavenumbers frequencies phase advances near higher up Possible generating this wave involve nonlinear interactions between other harmonics originating middle atmosphere. Our results thus suggest yet another phenomenon driven dynamical links atmosphere ionosphere.