Synthetic aperture radar for offshore wind resource assessment and wind farm development in the UK

The UK has an abundant offshore wind resource with offshore wind set to grow rapidly over the coming years. Optimisation of energy production is of the utmost importance given the high installation and maintenance costs of offshore turbines; accurate estimates of wind speed characteristics are critical during the planning process. While operational assessment methods which rely upon in-situ observations or flow models do little to explore the spatial variability of the wind resource, synthetic aperture radar (SAR) data from platforms such as ERS 1/ 2 and ENVISAT can provide wind field speed estimates at a spatial resolution of a few km² accurate to within ±2 m/s. This paper will present the results of the first phase of a project examining the use of SAR for wind resource assessment around the coast of the UK Two algorithms are explored that combine SAR imagery with NWP output; DWSA which estimates wind speed based upon NWP directions alone and SWRA where wind vector inversion is achieved using a statistical approach to combine NWP wind directions and speeds with backscatter information. Results show SWRA to produce superior wind speed estimates, generally within ∼2 m/s of in situ observations. Additionally expected improved wind speed estimation of CMOD-5 over CMOD-4 at high wind speeds is demonstrated.