Small-scale variability of the wind field over a typical Scandinavian lake

Lake flow and transport models are largely dependent on the accuracy of the input data like wind forcing. In the current study the WAsP (Wind Atlas Analysis and Application Program) model was used for the calculation of wind conditions on a typical north European lake, lake Längelmävesi-Roine. Lake is relatively small and landscape fragmented. The main objective was to estimate how well the measurement made at one location represented conditions in different parts of the lake. It was found that, due to the influence of orography and surface roughness, the mean wind speed values could at certain locations be about 30% weaker than those at the measurement site. The variation in mean wind direction was small. The results of the study demonstrate that models like WAsP can provide valuable and substantial information and thus the use of wind models can improve the quality of lake model calculations.