Extreme values of wind speeds in Denmark

This report contains extreme statistics for a full 9-year record of 10-min averages of wind speed obtained at Sprogø in the Great Belt. Verification of the extreme data is provided through a comparison with extreme data from three other sites: Risø, Nibe, and the Dan/Gorm field. The methodology includes terrain descriptions of the sites involved.

Both the Sprogø and Risø data are corrected for terrain, wake, and tower shadow effects, on applying the double-vertical extrapolation procedure of the European Wind Atlas. Extreme statistics are applied for both raw and corrected data using the Peakover-Threshold method. Good resemblance is found between the extreme statistics based on corrected data from Sprogø and Risø.

A four-year and nine-mounth record of maximum 3-sec averages of turbulent wind fluctuations within a 10-min record is available from the Sprogø mast. Based on this record an extreme statistics analysis for gust speeds in stationary conditions is attempted, assuming independence between the mean wind speed and the relative gust amplitude.

In addition, extreme gust speeds are presented from storm periods with prevailing short-term instationarity. Finally, a short note is given on long-term fluctuations of the wind climate in Denmark. (author). 38 tabs., 50 ills., 34 refs..