Mass balance of three Svalbard glaciers reconstructed back to 1948

Abstract

A simple model using upper-air meteorological variables in the NCEP-NCAR Reanalysis database is used to model seasonal components of mass balance of three glaciers in Svalbard. The model was originally developed for glaciers in North America, and has been applied to glaciers in Norway, Sweden and Iceland. Over the period for which mass balance data are available for the three Svalbard glaciers, the model fit yields r2 values ranging from 0.46 to 0.61 for winter balance Bw and from 0.56 to 0.59 for summer balance B­s . Sensitivity to + 1 ° C warming was about -0.36 m yr-1 water equivalent (w.eq.), caused mainly by increased ablation and secondarily by shift of precipitation from snow to rain. Sensitivity to a 10% increase in precipitation was about + 0.06 m yr-1 w.eq. The model, calibrated over the period of observations, was used to extend the mass balance series back to 1948. At annual resolution, observed mass balance of the three glaciers correlates poorly with both the North Atlantic Oscillation (NAO) and with glaciers in Norway. Over two multiyear periods, the strongly positive NAO period 1990–1996 and the period afterward, glaciers in both Svalbard and especially Norway showed a pronounced decline in Bw. However, Bs for Svalbard glaciers was not more strongly negative after 1996, in contrast to glaciers in Norway.