Geometry and thermal regime of the King George Island ice cap, Antarctica, from GPR and GPS

• Published in: Annals of glaciology Vol. 51; no. 55; pp. 103 - 109
• Main Authors: Blindow, Norbert, Suckro, Sonja K., Rückamp, Martin, Braun, Matthias, Schindler, Marion, Breuer, Birgit, Saurer, Helmut, Simões, Jefferson C., Lange, Manfred A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2010; International Glaciological Society
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Snow. Ice. Glaciers; South Shetland Islands; Scotia Sea; Antarctic Ocean; polar regions; West Antarctica; Antarctica; Scotia Sea Islands; King George Island; Antarctica, Antarctic Peninsula; Antarctica, South Shetland Is; Antarctica, South Shetland Is., King George I; Temperature distribution; water body; thickness; topography; Atmosphere cryosphere interaction; Ice flow; Measurement campaign; Subpolar zone; ground-penetrating radar; Global Positioning System; meltwater; bedrock; piezometric surface; ice fields; Radar observation; ice caps; Observation data; climate change; geophysical surveys
• DOI: 10.3189/172756410791392691
• ISSN: 0260-3055

King George Island is the largest of the South Shetland Islands, close to the tip of the Antarctic Peninsula. The annual mean temperature on the island has increased by 1°C during the past three decades, and the ice cap that covers the majority of the island is sensitive to climatic change. We present data from two field campaigns (1997 and 2007): 700 km of global positioning system (GPS) and ground-penetrating radar (GPR) profiles were collected on Arctowski Icefield and on the adjacent central part. The data were analysed to determine the surface and bed topography and the thermal regime of the ice. Average ice thickness is 250 m and maximum thickness is 420 m. The GPR profiles show isochrones throughout the ice cap which depict the uparching of Raymond bumps beneath or close to the ice divides. A water table from percolation of meltwater in the snowpack shows the firn-ice boundary at ∼ 3 5 m depth. The firn layer may be temperate due to the release of latent heat. In the area below 400ma.s.l., backscatter by water inclusions is abundant for ice depths below the water table. We interpret this as evidence for temperate ice. Scatter decreases significantly above 400 m. Ice temperatures below the water table in this part of the ice cap are subject to further field and modelling investigations.