Recent Ice Ages on Mars: The role of radiatively active clouds and cloud microphysics

Abstract : Global Climate Models (GCMs) have been successfully employed to explain the origin of many glacial deposits on Mars. However, the Latitude Dependent Mantle (LDM), a dust-ice mantling deposit that is thought to represent a recent "Ice Age", remains poorly explained by GCMs. We reexamine this question by considering the effect of radiatively active water-ice clouds (RACs) and cloud microphysics. We find that when obliquity is set to 35°, as often occurred in the past 2 million years, warming of the atmosphere and polar caps by clouds modifies the water cycle and leads to the formation of a several centimeter-thick ice mantle poleward of 30° in each hemisphere during winter. This mantle can be preserved over the summer if increased atmospheric dust content obscures the surface and provides dust nuclei to low-altitude clouds. We outline a scenario for its deposition and preservation that compares favorably with the characteristics of the LDM.
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Jean-Baptiste Madeleine, James W. Head, François Forget, Thomas Navarro, Ehouarn Millour, et al.. Recent Ice Ages on Mars: The role of radiatively active clouds and cloud microphysics. Geophysical Research Letters, American Geophysical Union, 2014, 41 (14), pp.4873-4879. 〈10.1002/2014GL059861〉. 〈hal-01023522〉

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