Retrieving wind statistics from average spectrum of continuous-wave lidar
- 1DTU Wind Energy, Risø Campus, Technical University of Denmark, Roskilde, Denmark
- 2ZephIR Ltd., The Old Barns, Fairoaks Farm, Hollybush, Ledbury, HR8 1EU, UK
- 3LM Wind Power, Lunderskov, Denmark
Abstract. The aim of this study is to experimentally demonstrate that the time-average Doppler spectrum of a continuous-wave (cw) lidar is proportional to the probability density function of the line-of-sight velocities. This would open the possibility of using cw lidars for the determination of the second-order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems.