Numerical investigations of extreme winds over Switzerland during 1990–2010 winter storms with the Canadian Regional Climate Model

Abstract

This study reports on the ability of the Canadian Regional Climate Model to simulate the surface wind gusts of 24 severe mid-latitude storms in Switzerland during the period 1990–2010. A multiple self-nesting approach is used, reaching a final 2-km grid which is centred over Switzerland, a country characterised by complex topography. A physically-based wind gust parameterization scheme is applied to simulate local surface gusts. Model performance is evaluated by comparing simulated wind speeds to time series at weather stations. While a number of simulated variables are reproduced in a realistic manner, the surface wind gusts show differences when compared to observed values. Results indicate that the performance of this parameterization scheme not only depends on the accuracy of the simulated planetary boundary layer, the vertical temperature, wind speed and atmospheric humidity profiles, but also on the accuracy of the reproduction of the surface fields such as temperature and moisture.