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Sub-diurnal methane variations on Mars driven by barometric pumping and planetary boundary layer evolution
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  • John P Ortiz,
  • Harihar Rajaram,
  • Philip H. Stauffer,
  • Kevin W. Lewis,
  • Roger C. Wiens,
  • Dylan Robert Harp
John P Ortiz
Los Alamos National Laboratory (DOE)

Corresponding Author:[email protected]

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Harihar Rajaram
Johns Hopkins University
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Philip H. Stauffer
Los Alamos National Laboratory (DOE)
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Kevin W. Lewis
Johns Hopkins University
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Roger C. Wiens
Purdue University
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Dylan Robert Harp
The Freshwater Trust
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Abstract

In recent years, the Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory (MSL) Curiosity rover has detected methane variations in the atmosphere at Gale crater. Methane concentrations appear to fluctuate seasonally as well as sub-diurnally, which is difficult to reconcile with an as-yet-unknown transport mechanism delivering the gas from underground to the atmosphere. To potentially explain the fluctuations, we consider barometrically-induced transport of methane from an underground source to the surface, modulated by temperature-dependent adsorption. The subsurface fractured-rock seepage model is coupled to a simplified atmospheric mixing model to provide insights on the pattern of atmospheric methane concentrations in response to transient surface methane emissions, as well as to predict sub-diurnal variation in methane abundance for the northern summer period, which is a candidate time frame for Curiosity’s potentially final sampling campaign. The best-performing scenarios indicate a significant, short-lived methane pulse just prior to sunrise, the detection of which by SAM-TLS would be a potential indicator of the contribution of barometric pumping to Mars’ atmospheric methane variations.
09 Aug 2023Submitted to ESS Open Archive
09 Aug 2023Published in ESS Open Archive