Operational since 2004, the National Centre for Wind Turbines at Høvsøre, Denmark has become a reference research site for wind-power meteorology. In this study, we review the site, its instrumentation, observations, and main research programs. The programs comprise activities on, inter alia, remote sensing, where measurements from lidars have been compared extensively with those from traditional instrumentation on masts. In addition, with regard to wind-power meteorology, wind-resource methodologies for wind climate extrapolation have been evaluated and improved. Further, special attention has been given to research on boundary-layer flow, where parametrizations of the length scale and wind profile have been developed and evaluated. Atmospheric turbulence studies are continuously conducted at Høvsøre, where spectral tensor models have been evaluated and extended to account for atmospheric stability, and experiments using microscale and mesoscale numerical modelling.

[1] On the basis of an extensive data set from the air-sea interaction station Ö stergarnsholm in the Baltic Sea, the dependence of drag on the ocean of wave state parameters has been studied for near-neutral conditions. For developing sea, the drag depends on wave age, u * /c p (u * friction velocity and c p the phase speed of the dominant waves), in agreement with recent findings over the World Ocean, strongly supporting that the Ö stergarnsholm station can be relied upon to give results representative of open ocean conditions. For such conditions, it is demonstrated that the logarithmic wind law is indeed valid. For mixed sea/swell the logarithmic wind law is not valid and the drag coefficient, C D depends on two parameters representing the wave state: u * /c p and E 1 /E 2 , where E 1 is the energy of the relatively long waves (having a phase velocity larger than the wind speed at 10 m) and E 2 , the short wave energy. Thus, plotting C D as a function of u * /c p gives a clear ordering of the data in parallel, sloping bands according to the value of E 1 /E 2 . Thus, whereas very young and slow waves affect the atmospheric flow similar to rigid roughness elements, with the occurrence of longer waves, an entirely different mechanism gains successively more importance and dynamical coupling with the atmospheric turbulence occurs. It may be speculated that the often observed kink in the wind profile represents the upper bound of a wave-boundary-layer, which is thus an order of magnitude deeper than predicted and observed during growing sea conditions.

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Extreme winds derived from simulations using mesoscale models are underestimated because of the effective spatial and temporal resolutions. This is reflected in the spectral domain as an energy deficit in the mesoscale range. The energy deficit implies smaller spectral moments and thus underestimation in the extreme winds. The authors have developed two approaches for correcting the smoothing effect resulting from the mesoscale model resolution that impacts the extreme wind estimation by taking into account the difference between the modeled and measured spectra in the high-frequency range. Both approaches give estimates of the smoothing effect that are in good agreement with measurements from several sites in Denmark and Germany.

Standard meteorological measurements from a number of masts around two Danish offshore wind farms have been used to study the spectral structure of the mesoscale winds, including the power spectrum, the co-and quadrature spectrum and the coherence. When average conditions are considered, the power spectra show universal characteristics, in agreement with the findings in literature, including the energy amplitude and the −5/3 spectral slope in the mesoscale range transitioning to a slope of −3 for synoptic and planetary scales. The integral time-scale of the local weather is found to be useful to describe the spectral slope transition as well as the limit for application of the Taylor