Modelling Slope Microclimates In The Mars Planetary Climate Model

By Keith Cowing
Status Report
June 28, 2023
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Modelling Slope Microclimates In The Mars Planetary Climate Model
Schema of the sub-grid scale slope parameterization. Each mesh of the Mars PCM is decomposed into sub-grid slopes (defined by characteristic slopes µi) or flat terrain. These subgrid terrains have their microclimate and the interactions between the atmosphere and surface are made through averaged values over the mesh. — astro-ph.EP

A large number of surface phenomena (e.g., frost and ice deposits, gullies, slope streaks, recurring slope lineae) are observed on Martian slopes.

Their formation is associated with specific microclimates on these slopes that have been mostly studied with one-dimensional radiative balance models to date. We demonstrate here that any Martian slope can be thermally represented by a poleward or equatorward slope, i.e., the daily average, minimum, and maximum surface temperatures depend on the North-South component of the slope.

Based on this observation, we propose here a subgrid-scale parameterization to represent slope microclimates in coarse-resolution global climate models. We implement this parameterization in the Mars Planetary Climate Model and validate it through comparisons with surface temperature measurements and frost detections on sloped terrains. With this new model, we show that these slope microclimates do not have a significant impact on the seasonal CO2 and H2O cycle.

Our model also simulates for the first time the heating of the atmosphere by warm plains surrounding slopes. Active gullies are mostly found where our model predicts CO2 frost, suggesting that the formation of gullies is mostly related to processes involving CO2 ice. However, the low thicknesses predicted there rule out mechanisms involving large amounts of ice. This model opens the way to new studies on surface-atmosphere interactions in present and past climates.

L.Lange, F.Forget, E.Dupont, R.Vandemeulebrouck, A.Spiga, E.Millour, M.Vincendon, A.Bierjon

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2306.12449 [astro-ph.EP] (or arXiv:2306.12449v1 [astro-ph.EP] for this version)
Submission history
From: Lucas Lange
[v1] Tue, 20 Jun 2023 19:46:47 UTC (5,984 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻