Author(s): Donald K. Perovich

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Abstract: The summer melt cycle of Arctic sea ice is in large part governed by the partitioning of solar radiation between reflection to the atmosphere, absorption in the ice, and transmission to the ocean. Observations from the year-long SHEBA field experiment are combined with a radiative transfer model to compute aggregate-scale estimates of this partitioning. Prior to the onset of melt at SHEBA, the surface consisted primarily of large, snow-covered ice floes with only a few percent covered by open water. The calculations indicated that approximately 80% of the incident solar radiation was reflected, approximately 17% was absorbed in the snow, and less than 3% was transmitted to the ocean. As summer melt progressed, the surface evolved into a variegated mixture of bare ice, melt ponds, and leads. By August 7 there was approximately 60% bare ice, 20% ponds, and 20% leads. These changes in the composition of the ice cover had a profound impact on the partitioning of the incident solar radiation. Under these conditions, only 45% of the incident solar radiation was reflected, while 33% was absorbed in the ice and contributed to surface and internal melting. The remaining 22% was transmitted to the ocean, where it was available for melting on the bottom and lateral edges of the ice.

DOI:

Year: 2002