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Recent Ice Ages on Mars: The role of radiatively active clouds and cloud microphysics
Author(s) -
Madeleine J.B.,
Head J. W.,
Forget F.,
Navarro T.,
Millour E.,
Spiga A.,
Colaïtis A.,
Määttänen A.,
Montmessin F.,
Dickson J. L.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl059861
Subject(s) - mars exploration program , ice age , atmospheric sciences , geology , glacial period , climatology , environmental science , northern hemisphere , water cycle , astrobiology , physics , geomorphology , ecology , biology
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.