Work Description

Title: Mars Thermospheric Neutral Winds: Mars Global Ionosphere-Thermosphere Model (M-GITM) Simulated Datasets for Comparison to MAVEN Spacecraft Measurements Open Access Deposited

http://creativecommons.org/licenses/by-nc/4.0/
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Methodology
  • Simulated zonal and meridional neutral winds of the Mars thermosphere are calculated by the 3-D numerical model called M-GITM (Mars Global Ionosphere-Thermosphere Model), developed at the U. of Michigan. This is a climate model whose domain extends from the surface to ~250 km (Bougher et al., 2015). Neutral plus ion densities, neutral temperatures and winds are calculated on a 3-D grid (latitude, longitude, altitude) for NASA MAVEN spacecraft conditions corresponding to specific instrument measurements made. These 3-D model calculations are time-marching, making use of a finite-difference code which solves the Navier-Stokes equations for temperatures, composition, and winds. Large datacubes are created of M-GITM outputs fields for deposit on this archive.
Description
  • The NASA MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft, which is currently in orbit around Mars, has been taking monthly measurements of the speed and direction of the winds in the upper atmosphere of Mars between about 140 to 240 km above the surface. The observed wind speeds and directions change with time and location, and sometimes fluctuate quickly. These measurements are 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 the first comparison between direct measurements of the winds in the upper atmosphere of Mars and simulated winds and is important because it can help to inform us what physical processes are acting on the observed winds. Some wind measurements have similar wind speeds or directions to those predicted by the M-GITM model, but sometimes, there are large differences between the simulated and measured winds. The disagreements between wind observations and model simulations suggest that processes other than normal solar forcing may become relatively more important during these observations and alter the expected circulation pattern. 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 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

  • About 30 Neutral Gas and Ion Mass Spectrometer (NGIMS) wind campaigns (of 5 to 10 orbits each) have been conducted by the MAVEN team (Benna et al., 2019). Five of these campaigns are selected for detailed study (Roeten et al. 2019). The Mars conditions for these five campaigns have been used to launch corresponding M-GITM code simulations, yielding 3-D neutral wind fields for comparison to these NGIMS wind observations. The M-GITM datacubes used to extract the zonal and meridional neutral winds, along the trajectory of each orbit path between 140 and 240 km, are provided in this Deep Blue Data archive. README files are provided for each datacube, detailing the contents of each file. A general README file is also provided that summarizes the inputs and outputs of the M-GITM code simulations for this study.
Creator
Depositor
  • bougher@umich.edu
Contact information
Discipline
Funding agency
  • National Aeronautics and Space Administration (NASA)
ORSP grant number
  • PGN: F031116
Keyword
Citations to related material
  • Roeten, K. J., S. W. Bougher, M. Benna, P. R. Mahaffy, Y. Lee, D. Pawlowski, F. Gonzalez-Galindo, M. Lopez-Valverde, MAVEN/NGIMS thermospheric neutral wind observations: Interpretation using the M-GITM general circulation Model, J. Geophysical Research, submitted (2019)
Resource type
Last modified
  • 05/22/2019
Language
DOI
  • doi:10.7302/85qt-e980
CC License

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