A new enhanced temperature-index melt model including net solar and infrared radiation

Abstract

We proposed a new enhanced T-index model including net longwave radiation to evaluate glacier ice melt. We applied the methods for simulating ice melt at the Automatic Weather Station (AWS) site on the Forni Glacier (Italian Alps). The AWS has been continuously running since September 2005. We tested several models with increasing complexity (i.e. from the simplest degree-day to enhanced models including shortwave and longwave fluxes) in order to assess the best approach to be applied depending on the temporal resolution and to verify if the goodness of the calculation could depend also on the model type. We applied all models using measured meteorological data. We benchmarked the performance of each model against melt values estimated by means of the energy balance model. The results display that i) T-index features a high performance if applied at the seasonal scale, but the worst at daily and weekly resolution; ii) taking into account solar radiation seems to improve the models at a higher time resolution; iii) including the longwave input within the enhanced T-index model can be considered a simplification of the energy balance model and provides more accurate calculation of ablation depending on the time resolution.