A one-year long turbulence simulation using a WRF-LES based modeling system at Østerild

Here we show an intercomparison between turbulence simulations and measurements performed at a 250-m tall meteorological mast located at the wind turbine test center of Østerild in northern Denmark. The Weather Research and Forecasting model is used to perform the simulations. We use the model’s nesting capability to downscale the forcing reanalysis down to sub-kilometer domains, which are run in a large-eddy simulation fashion, thus being able to partly resolve turbulence. We find that the simulations are able to reproduce accurately the wind climatology of the site when compared to the observations at the mast. The wind power densities derived from the time series of 10-min mean wind speeds from simulations and observations differ by less than 2%. The observed turbulence conditions, in the form of histograms of the wind speed standard deviation, seem fairly well reproduced by the simulations, although there seems to be a tendency of lower simulated turbulence levels. This is also partly reflected when studying the behavior of the turbulence intensity with increasing mean wind speeds. Spectral analysis on the mean wind speed time series reveals that the simulations are able to reproduce the energy content of the observations rather well, but we find a slight larger variability of simulated winds at frequencies larger than 1 h.