| Abstract |
We report a new set of stellar occultation measurements for nightside temperature profiles made by the Mars Atmosphere and Volatile EvolutioN/Imaging Ultraviolet Spectrograph that provide evidence for a recurring layer of warm air between 70 and 90 km altitudes in the nightside mesosphere of Mars during Ls = 0-180 in Martian Year 33-34. The nightside profiles reveal a recurring peak of atmospheric temperature around 80 km over the equator to the middle latitudes in the northern hemisphere. The predictions of the Mars Climate Database have a warm layer with much smaller amplitudes. The observed peak amplitudes are larger than those predicted by the model by up to 90 K. Wavenumber-3 structures are seen in the warm layer that are potentially signatures of thermal tides or stationary planetary waves, with amplitudes two times larger than predicted. Our result suggests that the circulation pattern of Mars' mesosphere is reminiscent of the nightside warm layer detected on Venus and interpreted by Bertaux et al. (2007) and of the Mesospheric Inversion layer on Earth (e.g., Meriwether and Gardner, 2000). |
