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  • Mars Thermospheric Responses to a Global Dust Storm (PEDE-2018): Mars Global Ionosphere-Thermosphere Model (M-GITM) Simulated Helium Distributions for Comparison to MAVEN Spacecraft Measurements

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    Creator:
    Bougher, Stephen W. and Roeten, Kali J.
    Description:
    The NASA MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft, which is currently in orbit around Mars, has been taking daily (systematic) measurements of the densities and temperatures in the upper atmosphere of Mars between about 140 to 240 km above the surface. Wind measurement campaigns are also conducted once per month for 5-10 orbits. These densities, temperatures and winds change with time (e.g. season, local time) and location, and sometimes fluctuate quickly. Global dust storm events are also known to significantly impact these density, temperature and wind fields in the Mars thermosphere. Such global dust storm period measurements can be compared to simulations from a computer model of the Mars atmosphere called M-GITM (Mars Global Ionosphere-Thermosphere Model), developed at U. of Michigan. This is an ongoing detailed comparison between direct global dust storm period measurements in the upper atmosphere of Mars and simulated MGITM fields and is important because it can help to inform us what physical processes are acting on the upper atmosphere during such large dust events. Since the global circulation plays a role in the structure, variability, and evolution of the atmosphere, understanding the processes that drive the winds in the upper atmosphere of Mars also provides key context for understanding how the atmosphere behaves as a whole system. A basic version of the M-GITM code can be found on Github as follows: https:/github.com/dpawlows/MGITM [less] About 4 months of Neutral Gas and Ion Mass Spectrometer (NGIMS) measurements of densities and winds have been made by the MAVEN team during the summer of 2018 (Elrod et al., 2019; Roeten et al 2022). For this specialized archive (Elrod et al. 2023), one reference measurement interval during this 2018 global dust storm (30-31 August 2018) is selected for detailed study of helium distributions (Elrod et al. 2023). The Mars conditions for this last of nine intervals have been used to launch corresponding M-GITM code simulations, yielding 3-D neutral density, temperature and wind fields for comparison to these NGIMS measurements. This last interval is used to provide M-GITM datacubes to explicitly extract the helium density (plus corresponding temperatures and neutral winds) along the trajectory of each orbit path between 140 and 240 km . A general README file is also provided for this Deep Blue Data archive detailing the contents of each file, while also summarizing the inputs and outputs of the M-GITM code simulations for this study.
    Keyword:
    Mars , NASA MAVEN spacecraft, Mars Thermosphere, Global Dust Strom of 2018, and Helium distribution
    Citation to related publication:
    Elrod, M. K., S. W. Bougher, K. Roeten, R. Sharrar, J. Murphy, Structural and Compositional Changes in the Upper Atmosphere related to the PEDE-2018 Dust Event on Mars as Observed by MAVEN NGIMS, Geophys. Res. Lett., (2019). doi: 10.1029/2019GL084378. and Elrod, M. K., S. W. Bougher, K. Roeten and K. Arnold, Surprising Decrease in the Martian He Bulge during PEDE-2018 and Changes in Upper Atmospheric Circulation, J. Geophysical Research, (2023), doi:XXX
    Discipline:
    Science