Stability of Mid - latitude snowpacks on Mars
نویسنده
چکیده
Synopsis: Mid-latitude snowpacks on Mars have been postulated to exist by Christensen [1], who also suggests that runoff from melting snowpacks on slopes might be responsible for carving gullies, and suggests that such snowpacks may currently exist on the walls of Dao Valles (approx. -33.0 lat.). The snowpacks were presumably formed during the last obliquity cycle, about 74,500 years ago. In this paper we investigate the rate at which a snowpack located at -33.0 latitude on a poleward-facing slope of 21 degree inclination sublimes on Mars. Our model includes the energy and mass balance of the snowpack, and diurnal variations in insolation. Our model results indicate that a dirty snowpack would very quickly sublime under current Martian climate conditions; a 10m thick snowpack of moderate density (550 Kg/m3) and albedo (0.21) would sublime in less than 5 years. A cleaner snowpack would sublime in less than 20 years. These results suggest that the snowpack in question almost certainly could not have survived for 74,500 years. The possibility of preservation of the snowpack by immediate burial is raised, but the burial would have to be at approx. 1m deep and would have had to occur within ~5 years. In addition, snowpack temperatures never reach the melting point, raising serious questions regarding the availability of runoff for gully incision.
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A recent ice age on Mars: Evidence for climate oscillations from regional layering in mid-latitude mantling deposits
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