Branlard, Emmanuel5; Pedersen, Anders Tegtmeier6; Mann, Jakob1; Angelou, Nikolas1; Fischer, Andreas1; Mikkelsen, Torben1; Harris, M.7; Slinger, C.7; Montes, B. F.8
1 Department of Wind Energy, Technical University of Denmark2 Aeroelastic Design, Department of Wind Energy, Technical University of Denmark3 Test and Measurements, Department of Wind Energy, Technical University of Denmark4 Meteorology, Department of Wind Energy, Technical University of Denmark5 Risø National Laboratory for Sustainable Energy, Technical University of Denmark6 Department of Photonics Engineering, Technical University of Denmark7 ZephIR Ltd.8 LM Wind Power
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.
Atmospheric Measurement Techniques, 2013, Vol 6, p. 1673-1683