Journal article
Observed seasonal changes in Martian hydrogen chloride explained by heterogeneous chemistry
- Abstract:
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Aims. The aim of this work is to show that the seasonal changes and vertical distribution profiles of hydrogen chloride (HCl) on Mars, as observed by the ExoMars Trace Gas Orbiter, are consistent with the production of gas-phase chlorine atoms from airborne dust and a subsequent rapid uptake of HCl onto water ice particles.
Methods. A 1D photochemistry model was equipped with a chlorine reaction network and driven by dust, water ice, and water vapour profiles measured by the ExoMars Trace Gas Orbiter instrumentation in Mars year 34. The release of Cl and O atoms from airborne dust via the hydration and photolysis of perchlorate within dust grains was parameterised using prior laboratory studies, and the heterogeneous uptake of chlorine species onto dust and water ice was included for processes known to occur in Eartha's atmosphere.
Results. Observed seasonal variations in Martian HCl are reproduced by the model, which yielded low HCl abundances (<1 ppbv) prior to the dust season that rise to 26 ppbv in southern latitudes during the dust season. Structured atmospheric layers that coincide with locations where water ice is absent are also produced. As a consequence of the Cl atoms released via our proposed mechanism, the atmospheric lifetime of methane is shortened by two orders of magnitude. This suggests that the production of Cl induced by the breakdown of hydrated perchlorate via UV radiation (or another electromagnetic radiation) in airborne Martian dust, consistent with observed profiles of HCl, could help reconcile reported variations in methane with photochemical models.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 14.0MB, Terms of use)
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- Publisher copy:
- 10.1051/0004-6361/202449546
Authors
- Funder identifier:
- https://ror.org/057g20z61
- Publisher:
- EDP Sciences
- Journal:
- Astronomy and Astrophysics More from this journal
- Volume:
- 687
- Article number:
- A191
- Publication date:
- 2024-07-12
- Acceptance date:
- 2024-05-03
- DOI:
- EISSN:
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1432-0746
- ISSN:
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0004-6361
- Language:
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English
- Keywords:
- Pubs id:
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2017683
- Local pid:
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pubs:2017683
- Deposit date:
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2024-08-06
Terms of use
- Copyright holder:
- Taysum et al
- Copyright date:
- 2024
- Rights statement:
- © The Authors 2024. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
- Licence:
- CC Attribution (CC BY)
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