Presentations

Abstract

Dual scanning lidar (DSL), combining two long-range scanning lidar devices with their beams intersecting at a measurement point of interest, is a promising measurement approach in particular for offshore wind resource and site assessment. Although this approach can in principle be applied to any location that is within the range of the scanning lidars, i.e. currently up to 10-15 km, the measurement accuracy of such a setup has not been verified under representative offshore conditions at long range yet. A suitable verification typically requires an offshore met mast at the target location that can provide traceable reference measurements not just for mean wind speed and direction but also turbulence intensity (TI), gusts and extreme winds, to cover the entire range of site conditions that should be covered in the test.  With the Centre for the Testing of Environmental Sciences Technology (C-Test) utilizing the National Offshore Anemometry Hub (NOAH) close to Newcastle, UK, we have found a suitable site. This site was used for a DSL performance verification test from April to August 2025 involving three scanning lidars of type Vaisala 400s, the results of which are presented and discussed in this contribution. The devices were set up in a triangle with about 6-7 km between each scanning lidar and the NOAH meteorological mast to the East and about the same distance between the North and South test pad, respectively, with both locations being onshore situated directly at the coast. At the North pad, we had installed two scanning lidar devices of the same type but different generations, which when combined with a 400S located on the south pad forms a dual scanning lidar pair.  The results of the test correspond to the first of its kind for this distance, being publicly presented and published. They confirm that DSL are indeed capable of providing accurate and precise wind resource data at this distance. The same applies to TI data which requires a more careful consideration of the system setup and configuration. DSL performance is further discussed in comparison to that of floating lidar systems, which are considered as de-facto standard measurement tool for offshore wind resource assessment in the wind industry but with limited capability/trust with regard to TI.  As a last aspect, we have analyse the measurement performance under storm conditions, focusing on storm Floris that was captured early August 2025. For the analysis, we not only have wind speed measurements at our disposal, but also detailed additional atmospheric and oceanographic measurement from a ceilometer, a microwave radiometer, and a wave buoy, that are part of C-Test or NOAH, respectively.