P080-0006
Modeling the impact of gravity waves on the thermosphere of Mars with a whole atmosphere gravity wave parameterization in the Mars Global Ionosphere-Thermosphere Model

Wednesday, 16 December 2020
Poster
Kali Roeten1, Stephen W Bougher2, Erdal Yiğit3, Alexander S Medvedev4, Mehdi Benna5 and Yuni Lee5, (1)University of Michigan Ann Arbor, Climate and Space Sciences and Engineering Department, Ann Arbor, MI, United States, (2)Climate and Space Sciences and Engineering Department, Ann Arbor, MI, United States, (3)George Mason University Fairfax, Department of Physics and Astronomy, Fairfax, VA, United States, (4)Max Planck Inst Solar System R, Gottingen, Germany, (5)NASA Goddard Space Flight Center, Greenbelt, MD, United States
Abstract:
Gravity waves play an important role in producing the observed general circulation and temperatures in the middle and upper atmosphere of Mars. The effects of gravity waves (GWs) in the upper atmosphere of Mars have been observed by the MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft even up to 250 km, where they are associated with fluctuations in densities and temperatures (e.g. Yiğit et al., 2015; England et al., 2017).

In order to study the influence of GWs in the Martian thermosphere, the spectral nonlinear whole atmosphere GW scheme of Yiğit et al. (2008) has been incorporated into the Mars Global Ionosphere-Thermosphere Model (M-GITM) for the first time. M-GITM is a 3D general circulation model (GCM) that extends from the surface through the thermosphere, with a resolution of 5° x 5° latitude-longitude spacing and 2.5 km in the vertical, and contains physics specifically appropriate for the upper atmosphere (Bougher et al., 2015). The whole atmosphere GW scheme was originally designed for and used in Earth GCMs (Yiğit et al., 2009), but has been modified for use in Mars GCMs (e.g. Medvedev et al., 2013; Yiğit et al., 2009). The wave-specific parameters used by the scheme are taken from observations, where available. This scheme accounts for both momentum deposition and thermal effects induced by propagating GWs from the lower atmosphere to the upper atmosphere.

Comparisons are done between M-GITM simulations which include the GW parameterization scheme and baseline simulations without GWs included. With the parameterized gravity wave effects included, the simulated mean flow in the upper atmosphere has been notably modified. In general, it is found that mean wind speeds decrease considerably at these altitudes with the addition of gravity wave effects.

These new M-GITM simulations using the GW parameterization scheme are also compared to thermospheric neutral wind observations from the NGIMS (Neutral Gas and Ion Mass Spectrometer) instrument on the MAVEN spacecraft. In addition to helping validate model results, these data-model comparisons will help determine the relative importance of gravity wave effects during different NGIMS wind observational campaigns.

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