An interpretation of Martian thermospheric waves based on analysis of a general circulation model

Planetary-scale longitudinal variations in density observed by the Mars Glo bal Surveyor accelerometer in the 125 km region can be qualitatively reprod uced by the NASA Ames Mars general circulation model in the 80 km altitude region, but only when locations having specific local times are used in the analysis. If the model results are averaged over all local times, the high -altitude longitudinal variations nearly disappear, leaving only a small st ationary wave 1 pattern, consistent with theory and previous modeling studi es. This analysis suggests that the observed wavelike structures are a resu lt of sampling tidal modes at a limited range of local times, rather than b y topographically forced Rossby waves as previously suggested.