MODELING ABLATION AND MASS-BALANCE SENSITIVITY TO CLIMATE-CHANGE OF STORSTROMMEN, NORTHEAST GREENLAND

Ablation measurements have been performed along a stakeline on Storstrommen glacier during two seasons of glaciological fieldwork in 1989 and 1990 and followed up by a short visit in 1992. As part of the investigation basic climate stations were operated during the 1989 and 1990 field seasons. Ablation and temperature data have served as input for a degree-day model covering the lowermost 1400 m of the glacier basin. By means of the model the mass-balance has been reconstructed back to 1949 using climatological time series from the coastal station Danmarkshavn. The results show no trend in mass-balance over the period from 1949 to 1991, although both mean annual temperature and precipitation had increased during the last 30 years. In the Northeast Greenland region, the GCM's predict an enhanced winter warming of 8-14-degrees-K as compared to a summer warming of only 2-4-degrees-K if atmospheric CO2 is doubled. Sensitivity tests are performed in which the required snow precipitation increase that matches the increased ablation from rise of summer temperatures are found. Another test shows the increase of ablation with different degrees of summer heating dTS based on GCM scenarios of greenhouse-induced warming. Under these conditions the change of the mass-balance of the ablation zone of Storstrommen is much different from previous estimates using equal summer and winter heating.