Assessment and validation of the offshore wind resource using WRF-derived and CCMP L3.0 ocean winds: south coast of South Africa

As the costs of erecting high-quality observation masts on the coasts are inhibitive, the assessment of offshore wind resource relies on the mesoscale modelling or/and satellite ocean winds. Hence, the offshore wind resource maps at 10 m off the south coast were assessed from a regional climate model (RCM) based on 3 km mesoscale wind simulations of 6-hourly resolution for the period of October 2006 to December 2011. To assess the ability of the WRF model in simulating the near-surface ocean winds as a basis for high-resolution wind resource assessment, the CCMP L3.0 ocean winds derived from combination of cross calibrated satellite observations at 10 m amsl were utilised. The mean deviations of the WRF-derived wind speed and power density range between −0.29 and 0.35 m/s; −33 and 60 W/m2, respectively when compared against the CCMP winds, representing significant improvement after downscaling. The existence of large-scale wind resource at 10 m height was recorded off the south coast with an estimated mean wind power density ranging between 340 and 505 W/m2. Furthermore, it is presented that the WRF modelling based on knowledge of the spatial and temporal scales of the atmospheric phenomena at a proposed site can be fully utilised for assessing the energy potentials at coastal region and over the land.