The regional distribution of the dry-snow zone on the Antarctic Peninsula north of 70˚ S

Abstract In order to estimate the contribution of the Antarctic Peninsula to global sea-level rise as a result of the observed warming in this region, the spatial extent of snow-melt-producing areas needs to be quantified. By using the dry-snow line derived from synthetic aperture radar (SAR) imagery as the uppermost limit of frequent or occasional surface melt, an estimation of the spatial extent of areas with non-zero ablation rates is facilitated. Three calibrated RADARSAT ScanSAR mosaics covering the northern Antarctic Peninsula were analyzed applying a threshold of –14 dB to identify the dry-snow line. The area of the dry-snow radar zone was determined to be 23300±2000 km2.Areas affected frequently or occasionally by snowmelt cover 85 000±9000 km2. In addition, the dry-snow line as derived from multi-temporal ERS-1/-2 imagery serves as an indicator of climate variability in the uppermost areas of polar glaciers and ice sheets. The upward shift of the dry-snow line between 1992 and 1998 on the eastern side of the Antarctic Peninsula at 68˚ S is interpreted as a direct response to the increasing number of high-temperature events during the 1991–2000 decade.

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