Using downscaled NCEP/NCAR reanalysis data for wind resource mapping

Abstract

[EN] Two problems arise when estimating numerically wind energy resources, namely: The low resolution of global-scale atmospheric models and the scarcity of meteorological observations to be used as boundary conditions for smaller-scale models. Downscaling techniques were developed to overcome these issues. These methods consist of using global-scale model output as boundary conditions of smaller-scale models. In this research a downscaling tool to refine NCEP/NCAR Reanalysis data using WAsP is presented. The downscaling technique proposed consists of extrapolating the wind climate at a given point using meteorological observations from another point by means of the WAsP model. Then, using time-marching NCEP/NCAR Reanalysis wind velocity values, on-line refined profiles of wind velocity and direction can be obtained. In order to assess the accuracy of the described tool, data of two episodes of 48 hours are downscaled and compared to meteorological observations at two different climates. A sensitivity analysis is performed in order to assess the effect that atmospheric stability and terrain roughness, among others, exert on the results. Results are not as accurate as expected, probably due to atmospheric instability or other factors neglected by the model. However, the main trends are followed when validating the model output using field measurements