Global-scale wave model estimates of nonmigrating tidal effects

Abstract

The global-scale wave model (GSWM) is used to investigate the effects of mean winds and realistic dissipation on upward propagating nonmigrating diurnal tidal components. We explore the signatures of two plausible tropospheric sources of these waves, namely, latent heat release associated with deep convective activity and the absorption of solar infrared radiation which varies zonally with longitudinal variations in tropospheric water vapor. Our calculations suggest that while nonmigrating components are up to a factor of 3 times smaller than the migrating diurnal tide, they modulate the latter and introduce measurable (∼10 m/s) longitudinal variability in the mesosphere and lower thermosphere. These effects are most pronounced in the GSWM for the latent heat source and during northern hemisphere winter.