On the Differences in Ablation Seasons of Arctic and Antarctic Sea Ice

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  • 1 U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH 03755
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Abstract

Arctic sea ice is freckled with melt ponds during the ablation season; Antarctic sea ice has few, if any. On the basis of a simple surface beat budget, we investigate the meteorological conditions necessary for the onset of surface melting in an attempt to explain these observations. The low relative humidity associated with the relatively dry winds off the continent and an effective radiation parameter smaller than that characteristic of the Arctic are primarily responsible for the absence of melt features in the Antarctic. Together these require a surface-layer air temperature above 0°C before Antarctic sea ice can melt. A ratio of the bulk transfer coefficients CH/CE less than 1 also contributes to the dissimilarity in Arctic and Antarctic ablation seasons. The effects of wind speed and of the sea-ice roughness on the absolute values of CH and CE seem to moderate regional differences, but final assessment of this hypothesis awaits better data, especially from the Antarctic.

Abstract

Arctic sea ice is freckled with melt ponds during the ablation season; Antarctic sea ice has few, if any. On the basis of a simple surface beat budget, we investigate the meteorological conditions necessary for the onset of surface melting in an attempt to explain these observations. The low relative humidity associated with the relatively dry winds off the continent and an effective radiation parameter smaller than that characteristic of the Arctic are primarily responsible for the absence of melt features in the Antarctic. Together these require a surface-layer air temperature above 0°C before Antarctic sea ice can melt. A ratio of the bulk transfer coefficients CH/CE less than 1 also contributes to the dissimilarity in Arctic and Antarctic ablation seasons. The effects of wind speed and of the sea-ice roughness on the absolute values of CH and CE seem to moderate regional differences, but final assessment of this hypothesis awaits better data, especially from the Antarctic.

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