Wind across land-water transitions: Application of an analytical model to numerical model output

To determine the wind speed over small inland water bodies, the wind measured at land stations has to be transformed to an open-water wind. The current transformation method used by Rijkswaterstaat employs the blending-height concept, which is a simplification of the Wieringa-Rijkoort Two-Layer Model. We here assess the validity of this approach by applying it to output form the high-resolution weather model HARMONIE. It turns out that the modelled winds in HARMONIE at land points and adjacent water points are not related according to the blending-height concept or the full Wieringa-Rijkoort model. Rather than using these models to infer the open-water wind, a well-calibrated and evaluated numerical atmosphere model should be used.