Wind Atlas Methodology

The central point in the wind transformation model of WAsP – the so-called Wind Atlas Methodology – is the concept of a Regional or Generalized Wind Climate, or Wind Atlas. This Generalized Wind Climate is the hypothetical wind climate for an ideal, featureless and completely flat terrain with a uniform surface roughness, assuming the same overall atmospheric conditions as those of the measuring position.

The basic "machine" of WAsP is a flow model, representing the effect of different terrain features:

terrain height variations
terrain roughness
sheltering obstacles

To deduce the Generalized Wind Climate from measured wind in actual terrain the WAsP flow model is used reversely, to remove the local terrain effects

To deduce the wind climate at a location of interest from the Generalized Wind Climate, the WAsP flow model is used to introduce the effect of terrain features

The concept of the Regional Wind Climate links the wind data from a measuring mast to the predicted wind climate and wind resources at locations of interest, typically a candidate site for a wind turbine or a wind farm.

The wind atlas methodology makes it possible to transfer detailed information about the wind climate from one location (the predictor site) to another (the predicted site). For an observational wind atlas, the predictor site is a real-world wind measurement. For a numerical wind atlas, the predictor site is a grid point in a mesoscale modelling domain. In the latter case, one may think of the model grid point as a virtual met. station. The predicted site often corresponds to the location and height of a specific wind turbine generator. Many wind atlases are modelling-based and validated using measurements and observations.