A DISTRIBUTED SURFACE ENERGY-BALANCE MODEL FOR A SMALL VALLEY GLACIER.1. DEVELOPMENT AND TESTING FOR HAUT-GLACIER-DAROLLA, VALAIS SWITZERLAND

This paper describes the development and testing of a distributed surf ace energy-balance model used to calculate rates of surface melting at Haut Glacier d'Arolla, Valais, Switzerland. The model uses a digital elevation model (DEM) of the glacier surface and surrounding topograph y together with meteorological data collected at a site in front of th e glacier to determine hourly or daily totals of the energy-balance co mponents and hence of melting over the entre surface of the glacier wi th a spatial resolution of 20 m. The model can also be used to determi ne temporal and spatial variations in snow depth, snow-line position a nd glacier surface albedo. Calculations from the model are compared wi th observations made along the glacier centre line in 1990, and in gen eral the model performs very well. The correlation coefficient between calculated and measured snow-line elevation, albedo and ablation are 0.99, 0.85 and 0.81, respectively. The main source of error between mo delled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model.