Modelling albedo and distributed snowmelt across a low hill in Svalbard

A land-surface model is used to simulate the albedo and mass of patchy snowcovers during radiation-driven melt for three years at a site in Svalbard. Performing single energy and mass balance calculations for the combined snow-covered and snow-free parts of the surface gives a faster decrease in albedo than observed because too much of the solar radiation absorbed by the composite surface is used to melt snow. Representing the snowcover separately allows the model to be calibrated to give a good match to the observed albedo for each of the years studied. A single set of model parameters cannot, however, give a good simulation for all of the years. The average snow mass and snowcover fraction measured on a grid of points can be simulated using either a distributed version of the model or a more efficient tiled version supplied with the observed relationship between snow mass and fractional coverage. Parameters obtained by optimising the snow mass simulations are more consistent from year to year than from the albedo simulations.