A pioneer mass balance estimate for a Patagonian glacier: Glaciar De los Tres, Argentina

Up to now, the database of World Glacier Monitoring Service does not contain mass balance for Patagonian glaciers. The first mass balance data from this region are now presented. In 1995/1996, an investigation including glaciological, meteorological and hydrological monitoring was carried out on Glaciar de los Tres in Mt. FitzRoy Region, Santa Cruz, Argentina. Mass balance calculations were based on direct estimates of its components — winter and summer balances, using the stratigraphic reporting system. Comparison of the glacier meteorology with those in the foothills reveals peculiarities in vertical temperature and precipitation gradients. Correlations with lowland meteorological records were used for correcting raw field data and for final calculation of mass balance parameters. Mass balance was slightly positive (+70 mm w.e.), with accumulation of 2320 mm and ablation of 2250 mm w.e. Three corresponding maps of these parameters are drawn. In spite of a positive 1995/1996 balance, the glacier front retreated 3 m, indicating the past glacier regime. Glacier retreat is the prevalent pattern of the Andes, but the contemporary state of alpine glaciers in the Argentine sector of Patagonia seems to be relatively more favourable.