Validation of KNW atlas with publicly available mast observations (Phase 3 of KNW project)

A. Stepek ...(etc.), Ministry of Infrastructure and the Environment, Royal Netherlands Meteorological Institute (KNMI)
De Bilt : KNMI

The KNW (KNMI North Sea Wind) atlas is based on the ERA-Interim reanalyses dataset which captures 35 years (1997-2013) of meteorological measurements and generates 3D wind fields consistent with these measurements and the laws of physics. This dataset is “downscaled” using the state-of-the-art weather forecasting model, HARMONIE with a horizontal grid of 2.5 km. The result is a high resolution dataset of 35 years: the KNW dataset. In this report the KNW dataset is validated against publicly available wind measurements from three tall offshore wind masts: OWEZ, FINO1 and MMIJ (Meteorological Mast Ijmuiden). The difference between the measured wind speeds (averaged over periods when the mast measurements were undisturbed by nearby wind parks) and the KNW values is less than 0.2 m/s for all masts and all measurement heights. The ERA-HARMONIE wind speeds were tuned to match the measurements made at KNMI’s 200 m tall meteorological mast at Cabauw and the same wind shear correction factor was applied uniformly throughout the whole KNW atlas area. The validation results imply that the accuracy of the long term average wind speeds of the KNW atlas is comparable to that of the measurements (cup and sonic anemometer and LIDAR). The same can be said of the estimates of the once in 10 year extreme wind speeds for heights around wind turbine hub height.

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(Technical report = Technisch rapport ; TR-352)