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>Solar-forced roughening of Antarctic glaciers and the Martian icecaps: How surficial debris and roughness affect glacial melting in Taylor Valley, Antarctica and how this can be applied to the Martian icecaps.
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Solar-forced roughening of Antarctic glaciers and the Martian icecaps: How surficial debris and roughness affect glacial melting in Taylor Valley, Antarctica and how this can be applied to the Martian icecaps.
Glaciers in the McMurdo Dry Valleys of Antarctica exhibit significant variations in surface roughness from smooth surfaces to large basins and canyon up to 15 meters deep and 100 meters across. The walls defining these basins and canyons show a consistent asymmetry, with near-vertical slopes facing the direction of maximum irradiance (north) and slopes of 30 to 40 degrees otherwise. Energy balance and modeling studies presented here show that these features generate their own microclimate. The radiation and turbulent terms of the energy balance within the basins differ significantly from those on adjacent horizontal surfaces. Radiation absorption within the basins is also strongly affected by basin geometry, with increased radiation on the north facing walls and reduced radiation on the south facing slopes relative to adjacent horizontal surfaces. Averaged over an entire basin, these variations in radiation receipt result in increased melt from the basins as compared with adjacent horizontal surfaces.; The basins and canyons appear to evolve from patches of surficial debris. To support this hypothesis, results from dust plot experiments and modeling of cryoconite hole growth are presented. Experiment results highlight the effects of debris on surface energy balance. The modeling indicates that evolution of cryoconite holes is slow as long as the holes are ice-covered. Holes of a meter or more in diameter with no ice cover can rapidly deepen, developing a geometry similar to that of the large basins.; The dry valleys environment may serve as a terrestrial analogue for the Martian icecaps. The Martian icecaps exhibit two types of roughness features: large troughs of up to 100 km in length, 10 km wide and a kilometer deep that incise both the north and south polar residual caps, and “swiss-cheese” terrain, fields of circular basins 10 m deep and 100 m across found on the south polar residual cap near 87°S. Comparison of the Martian trough and basin features with similar features in the dry valleys suggests that flow closure of the north polar grooves is required to explain groove geometry. Further comparison may tell us much about Martian ice composition and ice flow rates.
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