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Constraining the evolution and origin of methane plumes on Mars

Holmes, James; Patel, Manish and Lewis, Stephen (2018). Constraining the evolution and origin of methane plumes on Mars. In: AGU Fall Meeting, 11-15 Dec 2017, New Orleans, USA.

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Abstract

Future trace gas observations by the Nadir and Occultation for Mars Discovery (NOMAD) and Atmospheric Chemistry Suite (ACS) instruments on the ExoMars Trace Gas Orbiter (TGO) spacecraft will be the first instruments able to provide vertical profiles of multiple trace gas species, including methane. For interpretation and understanding of the retrieved methane vertical profiles, modelling studies are required to scrutinise between the different proposed mechanisms of methane release into the atmosphere, with global circulations models (GCMs) providing an invaluable tool to investigate the evolution of trace gas plumes and provide constraints on where the original source could be located, and potentially clues to its origin.

This study investigates the vertical evolution of methane from multiple different source emission scenarios, using the state-of-the-art LMD-UK Mars GCM coupled to the Analysis Correction assimilation scheme. For the methane emission scenarios in this study, temperature retrievals from the Thermal Emission Spectrometer are assimilated. With the assimilation scheme ensuring the wind fields are consistent with the thermal data input to the model, the assimilation process ensures the optimal dynamical state of the atmosphere and subsequently the best constraint on the transport of tracers in the martian atmosphere.

We show that at methane release rates constrained by previous observations and modelling studies, discriminating whether the methane source is a sustained or instantaneous surface emission requires at least ten sols of tracking the emission. A methane source must also be observed within five to ten sols of the initial emission to distinguish whether the emission occurs directly at the surface or within the atmosphere via destabilisation of metastable clathrates. The added constraint on global winds by the assimilation of thermal data is critical when attempting to backtrack the methane to its original source location.

Item Type: Conference or Workshop Item
Copyright Holders: 2018 The Authors
Project Funding Details:
Funded Project NameProject IDFunding Body
Case for Support for Modelling and Data Assimilation Science Co-I on the ExoMars Trace Gas Orbiter. (SP-10-073-SL)ST/I003096/1STFC (Science & Technology Facilities Council)
Astronomy and Planetary Sciences at the Open UniversityST/L000776/1STFC (Science & Technology Facilities Council)
Support for Science Co-I's on the ExoMars Trace Gas Orbiter Instruments. (SM-10-074-MP)ST/I003061/1STFC (Science & Technology Facilities Council)
Modelling and retrieval of martian dust, ice and ozone from ExoMars NOMAD dataST/P001262/1UKSA UK Space Agency
UPWARDSUPWARDS-633127European Union Horizon 2020
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 53617
Depositing User: James Holmes
Date Deposited: 05 Mar 2018 10:40
Last Modified: 02 May 2019 15:31
URI: http://oro.open.ac.uk/id/eprint/53617
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