Dynamical downscaling of precipitation in Iceland 1961-2006

Atmospheric flow over Iceland has been simulated for the period January 1961 to July 2006, using the mesoscale MM5 model driven by initial and boundary data from the European Centre for Medium Range Weather Forecasts (ECMWF). Firstly, the simulated precipitation is compared to estimates derived from mass balance measurements on the Icelandic ice caps. It is found that the simulated precipitation compares favourably with the observed winter balance, in particular for Hofsjokull, where corrections to take liquid precipitation and/or winter ablation into account have been made, and for the outlet glaciers Dyngjujokull and Bruarjokull. Secondly, the model output is used as input to the WaSiM hydrological model to calculate and compare the runoff with observed runoff from six watersheds in Iceland. It is found that model results compare favourably with observations. Overall, the MM5 V3-7 is somewhat better than the MM5 V3-5. The V3-7 is drier than V3-5 on upstream slopes.