A distributed surface energy-balance model for complex topography and its application to Storglaciären, Sweden

A grid-based surface energy-balance mass-balance model has been developed to simulate snow- and ice melt in mountainous regions with an hourly resolution. The model is applied to Storglaciären, a valley glacier in Sweden, using a 30 m resolution digital elevation model. Emphasis is directed towards computing the radiation components. These are modelled individually, considering the effects of slope angle, aspect and effective horizon. A new parameterization for snow albedo is suggested, modifying the albedo of the preceding hour as a function of time after snowfall, air temperature and cloudiness. The model is used to provide the meltwater input for discharge modelling and to assess the influence of the individual components on melt. Results are validated by means of observed melt rates, patterns of snow-line retreat and proglacial discharge. In general, simulations are in good agreement with observations. In particular, the diurnal and seasonal fluctuations of discharge are simulated remarkably well.