Extreme winds from the NCEP/NCAR reanalysis data

In this study, we test a method to estimate the extreme winds by using the NCEP/NCAR reanalysis data. From the reanalysis pressure or geopotential height records, the geostrophic wind is first calculated, and then extrapolated to 10 m height over a homogeneous surface with roughness length of 0.05 m, i.e. the so‐called standard wind. The software Wind Analysis and Application Program will then use this standard wind in a flow model, with the roughness, orography and obstacles around the turbine site to obtain the site‐specific wind. The ‘annual maximum method’ is used to calculate the 50 year wind. We examined extreme winds in different places where the strongest wind events are weather phenomena of different scales, including the mid‐latitude lows in Denmark, channelling winds in the Gulf of Suez, typhoons in the western North Pacific, cyclones in the Caribbean Sea, local strong winds: the Mistral in the Gulf of Lions and the Bora in the north Adriatic Sea. It was found that the method introduced here can be applied to places where the extreme wind events are synoptic weather phenomena like in north‐western Europe, but a more complicated downscaling, e.g. based on a mesoscale model, is needed for places where the extreme wind events are of mesoscale origin. Copyright © 2009 John Wiley & Sons, Ltd.