Impacts of gravity wave activity on the Martian thermosphere: Simulations using a spectral nonlinear GW parameterization in M-GITM global simulations
Abstract
Gravity waves propagating from the lower atmosphere have been found to have impacts on the middle and upper atmosphere of Mars. Variations observed in densities and temperatures in the Martian thermosphere on scales associated with gravity waves have been observed up to at least $\sim$220 km (e.g. Yi\u{g}it et al, 2015; England et al., 2017). Modeling studies have also suggested that gravity waves can have significant impacts on the mean circulation throughout the mesosphere and thermosphere of Mars through momentum and energy deposition from dissipating gravity waves (e.g., Medvedev et al., 2011; Medvedev and Yi\u{g}it, 2012). In this analysis, the impacts of gravity waves on the Martian upper atmosphere, and in particular, on the thermospheric winds, will be discussed based on simulations from a Mars global circulation model, M-GITM (Mars Global Ionosphere-Thermosphere Model), which simulates the Martian atmosphere from the ground to $\sim$250 km. A nonlinear whole atmosphere gravity wave parameterization scheme (Yi\u{g}it et al., 2008) has been incorporated into M-GITM. This allows us to examine the modeled impacts of gravity waves on the thermospheric winds as well as to determine the relative importance of gravity wave impacts compared to other physical processes. The addition of this gravity wave scheme has been found to decelerate the mean thermospheric winds in M-GITM and has resulted in a cooler upper thermosphere relative to the simulations of M-GITM that did not include a gravity wave parameterization. Output from these simulations is also compared to observations of thermospheric winds obtained from the NGIMS (Neutral Gas and Ion Mass Spectrometer) instrument onboard the MAVEN (Mars Atmosphere and Volatile Evolution) orbiter. These observations of the Martian thermospheric winds were taken in-situ along MAVEN's trajectory from $\sim$150 -- 220 km in monthly campaigns (Benna et al., 2019; Roeten et al., 2019). Data-model comparisons help to identify gravity wave impacts on the mean circulation of the thermosphere as well as determine the relative role of gravity wave effects during specific NGIMS wind observational campaigns.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.779R