Wind Energy Mapping Using Synthetic Aperture Radar

Wind energy off-shore is gaining much interest due to the high wind power potentials. The need is to map wind climatology and regional wind patterns in coastal regions. In the WEMSAR (Wind Energy Mapping using Synthetic Aperture Radar) project three European sites will be covered near Norway, Denmark and Italy. Data to be used are from the ERS-2 C-band scatterometer with a 50 km resolution, from ERS-2 Ku-band and Topex Poseidon Ku-Band altimeter with a 7 km resolution and from SAR. The SAR data will be block averaged into 400 m resolution from ERS-2 C_VV, Radarsat C_HH and Envisat ASAR C_VV and C_HH beginning year 2000. For SAR data, the algorithm CMOD IFRE2 (Institute Francaise de Recherche pour L’Exploitation de la Mer) is used based on 3433 collocated pairs of buoys of NOAA and ECMWF (European Centre for Medium Range Weather Forecasts) with the accuracy of ∀2 m/s for a single retrieval. In the validation part of the WEMSAR project for wind energy retrieval, the ESA SAR (SAR.PRI (precision image format)) will be used because of the need for absolute calibration. Validation data are from long-term off-shore and coastal meteorological masts at the sites. Some masts are dedicated to wind power measurements including the roughness of sea and wave height. Optimal validation is crucial as wind energy varies with the third power of the wind speed. Also, the 10 or 19.5 m wind speeds will have to be calculated into 50-100 m height, i.e. the hub height of modern 600-1500 kW wind turbines. This calculation includes stability correction of the wind profiles. Wind analysis at mesoscale (1 km grid) with the non-hydrostatic KAMM (Karlsruhe Atmospheric Mesoscale Model) and WAsP (the Risoe Wind Atlas Analysis and Application Program) for micro-siting will be used. The aim is to link from meteorological mast data to spatial mapping of the wind energy potential based on satellite SAR data in coastal areas.