Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry

Abstract Recent observations from the ExoMars Trace Gas Orbiter (TGO) have revealed the presence of hydrogen chloride (HCl) in the martian atmosphere. HCl shows strong seasonality, primarily appearing during Mars' perihelion period before decreasing faster than projected from photolysis and gas...

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Main Authors: Paul M. Streeter, Kylash Rajendran, Stephen R. Lewis, Kevin S. Olsen, Alexander Trokhimovskiy, Oleg Korablev, Manish R. Patel
Format: Article
Language:English
Published: Wiley 2025-03-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2024GL111059
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author Paul M. Streeter
Kylash Rajendran
Stephen R. Lewis
Kevin S. Olsen
Alexander Trokhimovskiy
Oleg Korablev
Manish R. Patel
author_facet Paul M. Streeter
Kylash Rajendran
Stephen R. Lewis
Kevin S. Olsen
Alexander Trokhimovskiy
Oleg Korablev
Manish R. Patel
author_sort Paul M. Streeter
collection DOAJ
description Abstract Recent observations from the ExoMars Trace Gas Orbiter (TGO) have revealed the presence of hydrogen chloride (HCl) in the martian atmosphere. HCl shows strong seasonality, primarily appearing during Mars' perihelion period before decreasing faster than projected from photolysis and gas‐phase chemistry. HCl profiles also display local anti‐correlation with water ice aerosol. One candidate explanation is heterogeneous chemistry. We present the first results from a heterogeneous chlorine chemistry scheme incorporated into a Mars global climate model (GCM), with atmospheric dust/water ice parameterized as an HCl source/sink respectively. Results were compared against a Mars GCM with gas‐phase only chlorine chemistry and observations from TGO's Atmospheric Chemistry Suite. We found that the heterogeneous scheme significantly improved the modeled HCl seasonal, latitudinal, and vertical distribution, supporting a crucial role for heterogeneous chemistry in Mars' chlorine cycle. Remaining discrepancies show that further work is needed to characterize the exact aerosol reactions involved.
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series Geophysical Research Letters
spelling doaj-art-eec973f5c75a4fe9a44a3c6f4bc5ece72025-08-20T01:48:15ZengWileyGeophysical Research Letters0094-82761944-80072025-03-01526n/an/a10.1029/2024GL111059Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous ChemistryPaul M. Streeter0Kylash Rajendran1Stephen R. Lewis2Kevin S. Olsen3Alexander Trokhimovskiy4Oleg Korablev5Manish R. Patel6School of Physical Sciences The Open University Milton Keynes UKSchool of Physical Sciences The Open University Milton Keynes UKSchool of Physical Sciences The Open University Milton Keynes UKDepartment of Physics University of Oxford Oxford UKSpace Research Institute (IKI) Moscow RussiaSpace Research Institute (IKI) Moscow RussiaSchool of Physical Sciences The Open University Milton Keynes UKAbstract Recent observations from the ExoMars Trace Gas Orbiter (TGO) have revealed the presence of hydrogen chloride (HCl) in the martian atmosphere. HCl shows strong seasonality, primarily appearing during Mars' perihelion period before decreasing faster than projected from photolysis and gas‐phase chemistry. HCl profiles also display local anti‐correlation with water ice aerosol. One candidate explanation is heterogeneous chemistry. We present the first results from a heterogeneous chlorine chemistry scheme incorporated into a Mars global climate model (GCM), with atmospheric dust/water ice parameterized as an HCl source/sink respectively. Results were compared against a Mars GCM with gas‐phase only chlorine chemistry and observations from TGO's Atmospheric Chemistry Suite. We found that the heterogeneous scheme significantly improved the modeled HCl seasonal, latitudinal, and vertical distribution, supporting a crucial role for heterogeneous chemistry in Mars' chlorine cycle. Remaining discrepancies show that further work is needed to characterize the exact aerosol reactions involved.https://doi.org/10.1029/2024GL111059Mars atmospherechlorineheterogeneous chemistryGCMaerosols
spellingShingle Paul M. Streeter
Kylash Rajendran
Stephen R. Lewis
Kevin S. Olsen
Alexander Trokhimovskiy
Oleg Korablev
Manish R. Patel
Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
Geophysical Research Letters
Mars atmosphere
chlorine
heterogeneous chemistry
GCM
aerosols
title Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
title_full Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
title_fullStr Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
title_full_unstemmed Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
title_short Global Distribution and Seasonality of Martian Atmospheric HCl Explained Through Heterogeneous Chemistry
title_sort global distribution and seasonality of martian atmospheric hcl explained through heterogeneous chemistry
topic Mars atmosphere
chlorine
heterogeneous chemistry
GCM
aerosols
url https://doi.org/10.1029/2024GL111059
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