Open AccessForecasting offshore wind speeds above the North Sea
Author(s) -
Tambke Jens,
Lange Matthias,
Focken Ulrich,
Wolff JörgOlaf,
Bye John A. T.
Publication year - 2004
Publication title -
wind energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 92
eISSN - 1099-1824
pISSN - 1095-4244
DOI - 10.1002/we.140
Subject(s) - wind stress , wind shear , meteorology , wind speed , offshore wind power , environmental science , submarine pipeline , planetary boundary layer , wind gradient , thermal wind , boundary layer , geology , turbine , geodesy , atmospheric sciences , mechanics , physics , oceanography , turbulence , thermodynamics
We investigate the expected performance of short‐term wind power prediction systems for offshore sites in the German Bight and at Horns Rev. Despite the special meteorological situation over the North Sea, it is found that the accuracy of wind speed predictions provided by the numerical prediction model of the German weather service is comparable to that of onshore predictions. However, although relative forecast errors look promising, the absolute errors are fairly large, with a root mean square error up to 3 m s −1 for the 48 h forecast. Moreover, vertical wind profiles which are typically needed to calculate the wind speed at hub height are considered at Horns Rev. In all thermal conditions the measured profiles show significant deviations from the expected shapes. The reason for this has to be clarified. Assuming that the deviations are due to the physical processes in the marine boundary layer, we present an alternative approach to derive wind profiles over the ocean which involves the inertial coupling of the Ekman layers of atmosphere and sea via a wave boundary layer with constant shear stress. Profiles calculated by this method are compared with measured profiles, showing rather good agreement. Copyright © 2004 John Wiley & Sons, Ltd.