Simulations of precipitation in the complex terrain of Iceland and comparison with glaciological observations

Precipitation in the complex terrain of Iceland has been simulated with a numerical model (MM5) for a period of 12 years. The simulations are made with a horizontal resolution of 8 km and they are forced with boundaries from the ECMWF. Validation of precipitation simulations is particularly difficult where precipitation falls largely as snow in strong winds, because of significant underestimation of true ground precipitation by conventional observations. In view of this, precipitation has been estimated from observations of snow accumulation on major glaciers in central and eastern Iceland. This glaciological dataset is compared to the simulated precipitation. The numerical simulations reproduce with quite good accuracy the amount of precipitation and the observed interannual variability. The results are promising for the use of glaciological data for precipitation mapping and for validation of numerical simulations. The usefulness of high-resolution numerical simulations for mapping precipitation in data-sparse regions is confirmed. This is important for downscaling results from general circulation models simulating future climate and for predicting changes in regional precipitation.