High-Resolution Numerical Simulations of Windstorms in the Complex Terrain of Iceland

Two severe windstorms hitting the complex terrain of East Iceland and Northwest Iceland have been simulated with horizontal resolutions of 9, 3 and 1 km. The overall simulated wind field agrees well with observations and shows limited sensitivity to the parameterization of the effect of surface friction. Local effects such as downslope windstorms and lee-side sheltering are in general well reproduced. At a few locations, there is however significant difference between observed and simulated wind. This can be attributed to small scale non-resolved terrain features. Wind-gusts are predicted using output from the numerical simulations and the turbulence-based method of Brasseur. For locations where the mean wind speed is well simulated, the predicted wind gusts are in general in acceptable agreement with observations. The simulations presented here are a part of preparations for operational high-resolution NWP for Iceland.