Abstract
Simple models to calculate melt and refreezing are reviewed. Both degree-day and energy-balance models can give distributed melt inputs to ice-dynamics models but have only been tested extensively in West Greenland, and more data are needed from the remoter parts of Greenland. The energy-balance model is more realistic but needs input data that are not generally available over the whole ice sheet. On the other hand, degree-day factors vary from situation to situation although a value of about 8 kg m−2d−1deg−1for ice ablation is a reasonable first approximation as assumed in recent ice-dynamics models. Meltwater refreezing in the accumulation area can be modelled very simply but more detailed physical models are needed to describe the shifts in accumulation zones under different climates.