THE UPWARD SHIFT OF THE DRY SNOW LINE ON THE NORTHERN ANTARCTIC PENINSULA

• Main Author: Frank Rau
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Antarctic Peninsula; The Antarctic; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.495.8674; http://las.physik.uni-oldenburg.de/eProceedings/vol02_1/02_1_rau1.pdf

The central and northern parts of the Antarctic Peninsula are regions of Antarctica, where substantial climate warming has been documented over the past decades. However, as most information is restricted to the coastal areas, detailed information on the impact of the actual warming on the higher parts of the central mountain chain of the Peninsula is still lacking. Due to the absence of direct measurements in these areas, mapping the dry snow line by means of SAR-imagery provides an effective tool for monitoring purposes. Hereby, the dry snow line is regarded as the uppermost limit of frequent or occasional surface melt. It separates the dry snow zone covering the highest parts of polar glaciers and ice sheets from the percolation zone of the lower areas. In SAR-imagery, the corresponding dry snow radar zone is characterised by an extraordinary spatial and temporal radiometric stability of the backscatter values. It is not affected by any seasonal variations. The only mechanism that is believed to be able to cause a significant upward shift of the dry snow line is a change of the snow cover properties under melting conditions. Conversely, a downward shift of this boundary line is a consequence of continuous accumulation of dry and fine-grained snow and the absence of any melt event at the corresponding altitude range during several years. The present study based on multi-year ERS-1/2 data (1992 – 2000) investigates the dry snow line position on the eastern Antarctic Peninsula between 65.0 ° and 68.0 ° South. While there is no evident signal from the northern part detectable, a significant upward shift of the dry snow line was detected in the south of 65.7°S in the investigated area. This is interpreted as a direct response to the increasing number of high temperature events during the 1991-2000 decade.