Thermal effects of internal gravity waves in the Martian upper atmosphere

Abstract

For the first time, gravity wave‐induced heating and cooling effects were fully and interactively incorporated into a Martian general circulation model (GCM). Simulations with a comprehensive GCM with an implemented spectral nonlinear gravity wave (GW) parameterization revealed significant thermal effects of GWs in the mesosphere and lower thermosphere (MLT) between 100 and 150 km. Wave‐induced heating and cooling rates are comparable with those due to near‐IR CO2 heating and IR CO2cooling, correspondingly. Accounting for thermal effects of GWs results in a colder simulated MLT, with the most of cooling taking place in middle‐ and high‐latitudes. In the winter hemisphere, the temperature decrease can exceed 45 K. The colder simulated MLT is in a good agreement with the SPICAM stellar occultation measurements and Mars Odyssey aerobraking temperature retrievals. Our experiments suggest that thermal effects of GWs are probably a key physical mechanism in the MLT missing in contemporary Martian GCMs.