Comparison of energy balance and degree–day models of summer ablation on the Langjökull ice cap, SW-Iceland

Abstract

Physical and empirical degree-day models are presented which simulate melting of the Langjokull ice cap in {SW}-Iceland, during the ablation seasons 2001 to 2005. The models were derived and evaluated using micro-meteorological observations on the glacier and tested with mass balance observations. The observed daily melt rates were successfully simulated by energy balance calculations based on meteorological observations on the glacier. Air temperatures in the low-albedo surroundings of the glacier represent daily variations in the incoming radiation flux better than the damped boundary layer temperature above the melting glacier Comparison of the empirical degree-day and physical energy balance models indicates that for a regional temperature change less than 3 degrees C, the empirical degree-day model may provide realistic predictions of changes in glacier ablation.