Mars

High And Dry: Billion-year Trends In The Aridity Of River-forming Climates On Mars

By Keith Cowing
Press Release
astro-ph.EP
November 25, 2022
Filed under , ,
High And Dry: Billion-year Trends In The Aridity Of River-forming Climates On Mars
Additional example of flat crater-bottom deposits interpreted as playa/lake deposits (18°S 323°E, Luba crater). (a) Image is 4.9 km across; colors highlight elevation range from -650m (red) to -750m (white) (ESP_072479_1615/ESP_072545_1615 stereopair). Note the alluvial fan deposit extending down from the bottom right. The white lines trace layers whose elevation and orientation were measured (Fig. S8). (b) Close-up of the area corresponding to the right cluster of white lines in panel (a). Image is 1.85 km across. Colors highlight elevation range between -705 m and -751 m. (c) Close-up of the area corresponding to the left cluster of white lines in panel (a). Image is 1.5 km across. Colors highlight elevation range between -707 m (red) to -779 m (white). — astro-ph.EP

Mars’ wet-to-dry transition is a major environmental catastrophe, yet the spatial pattern, tempo, and cause of drying are poorly constrained.

We built a globally-distributed database of constraints on Mars late-stage paleolake size relative to catchment area (aridity index), and found evidence for climate zonation as Mars was drying out. Aridity increased over time in southern midlatitude highlands, where lakes became proportionally as small as in modern Nevada. Meanwhile, intermittently wetter climates persisted in equatorial and northern-midlatitude lowlands.

This is consistent with a change in Mars’ greenhouse effect that left highlands too cold for liquid water except during a brief melt season, or alternatively with a fall in Mars’ groundwater table. The data are consistent with a switch of unknown cause in the dependence of aridity index on elevation, from high-and-wet early on, to high-and-dry later. These results sharpen our view of Mars’ climate as surface conditions became increasingly stressing for life.

Edwin S. Kite, Axel Noblet

Comments: Accepted by Geophysical Research Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Cite as: arXiv:2211.10552 [astro-ph.EP] (or arXiv:2211.10552v1 [astro-ph.EP] for this version)
Submission history
From: Edwin Kite
[v1] Sat, 19 Nov 2022 01:03:58 UTC (40,815 KB)
https://arxiv.org/abs/2211.10552
Astrobiology

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