Impacts of Gravity Waves in the Martian Thermosphere: The Mars Global Ionosphere-Thermosphere Model Coupled With a Whole Atmosphere Gravity Wave Scheme

Abstract

Gravity waves are a key mechanism that facilitates coupling between the lower and upper atmosphere of Mars. In order to better understand the mean, large-scale impacts of gravity waves on the thermosphere, a modern whole atmosphere, nonlinear, non-orographic gravity wave parameterization scheme has been incorporated into a three-dimensional ground-to-exosphere Mars general circulation model, the Mars Global Ionosphere-Thermosphere Model (M-GITM). M-GITM simulations utilizing the gravity wave parameterization indicate that significant gravity wave momentum is deposited in the thermosphere, especially within the altitude range of 90–170 km. This impacts the winds in the thermosphere; in particular, M-GITM simulations show a decrease in speed of the wind maximum in the summer hemisphere by over a factor of two. Gravity wave effects also impact the temperatures above 120 km in the model, producing a cooler simulated thermosphere at most latitudes. M-GITM results were also compared to upper atmospheric temperature and wind data sets from the MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft. Some aspects of wind data-model comparisons improved once the gravity wave scheme was added to M-GITM; furthermore, a cooler temperature profile produced by these new M-GITM simulations for the MAVEN Deep Dip 2 observational campaign resulted in a closer data-model comparison, particularly above 180 km. Overall, these modeling results show that gravity waves play an important role for the energy and momentum budget of the Martian thermosphere