MAVEN/NGIMS Thermospheric Neutral Wind Observations: Interpretation Using the M-GITM General Circulation Model
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Date
2019-12-12
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Citation of Original Publication
Roeten, Kali J.; Bougher, Stephen W.; Benna, Mehdi; Mahaffy, Paul R.; Lee, Yuni; Pawlowski, Dave; González‐Galindo, Francisco; López‐Valverde, Miguel Ángel; MAVEN/NGIMS Thermospheric Neutral WindObservations: Interpretation Using theM-GITM General Circulation Model; JGR Planets 124,12 ; 3283-3303 (2019); https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE005957
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Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Subjects
Abstract
Using a new observational technique, the NGIMS (Neutral Gas and Ion Mass Spectrometer) instrument on the MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft has the unique capability to measure horizontal thermospheric winds. Measured along the orbit track from periapsis (∼150 km) to ∼200 km, these are the first in situ observations of thermospheric winds at Mars. Significantly, this also means that simulated winds from a global circulation model can be compared to in situ observations from this part of the Martian atmosphere for the first time. In this study, observations from five NGIMS neutral wind campaigns have been compared to simulations from the Mars Global Ionosphere‐Thermosphere Model (M‐GITM), a ground to exosphere 3‐D general circulation model. By comparing NGIMS neutral wind observations to model simulations, the processes driving the winds and their variations in the upper atmosphere are examined. These comparisons show that for certain observational periods, the M‐GITM simulated winds can generally replicate the magnitude and/or direction of the NGIMS wind observations, while in others, significant differences occur. In general, wind observations from NGIMS campaigns with large orbit‐to‐orbit variability are not well replicated by M‐GITM, while campaigns with higher observed wind speeds are better captured by the model. Additionally, using these data‐model comparisons, the relative role of normal solar forcing and corresponding differential heating in driving thermospheric winds at Mars is found to be variable, likely acting as the primary driver under some conditions and secondary to other physical processes under others.