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 Hofsjo¨ kull, where corrections to take liquid precipitation and/or
winter ablation into account have been made, and for the outlet glaciers Dyngjujo¨ kull
and Bru´ arjo¨ kull. 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.
Key words | dynamical downscaling, glaciological data, hydrological data, MM5,
precipitation, WaSiM