Ablation on the ice cap of King George Island (Antarctica) : an approach from field measurements, modelling and remote sensing

• Main Author: Braun, Matthias H.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2001
• Subjects: Energiebilanz; Fernerkundung; Glaziologie; Klimaänderung; Antarktische Halbinsel; Online-Ressource; Antarctic; Antarctic Peninsula; King George Island; The Antarctic; Antarc*; Antarctica; Antarktis*; Ice cap
• Online Access: https://freidok.uni-freiburg.de/data/223; https://nbn-resolving.org/urn:nbn:de:bsz:25-opus-2231; https://freidok.uni-freiburg.de/dnb/download/223

On the background of various indications for on-going climatic and glacial changes on the Antarctic Peninsula, ablation on the King George Island ice cap was investigated during several summer seasons. Different methodological approaches were combined and the present glaciological and climatological knowledge of the ice cap compiled. The work focuses on surface energy balance modelling based on data from three summer field campaigns in the years 1995/96, 1997/98 and 1999/2000 at sites in different altitudes on the ice cap. Large-scale atmospheric weather patterns were derived from NOAA-IR composites and surface pressure charts. The ablation rates for the entire ice cap were estimated using a sensitivity analysis of a spatially distributed energy balance model. To obtain information on the snowmelt patterns during time periods without direct measurements, a multi-year data archive of ERS-1/2 data was evaluated. Generally, ablation was triggered by net radiation followed by sensible and latent heat fluxes. A distinct influence of the prevailing synoptic circulation on the energy exchange could be determined. Highest ablation rates were recorded during northerly to northwesterly advection of warm humid air masses. Snow cover in areas higher than 500 m asl was only wetted by very strong frontal advection events. This is in good agreement with the results from the evaluation of the SAR imagery and an comprehensive ground penetrating radar survey. The observed melt rates are one of the highest so far recorded in the Antarctic Peninsula region. A sensitivty analysis with the distributed model revealed a extraordinary high sensitivty of the ice cap towards further warming. Based on the data set from 1997/98 and the assumption of a 2 K air temperature increase, ablation on the King George Island ice cap would increase by about 60