Modelling the spectral shape of continuous-wave lidar measurements in a turbulent wind tunnel

Abstract. This paper describes the development of a theoretical model for turbulence spectrum measured by short-range, continuous-wave lidar (light detection and ranging). The performance was assessed measurements conducted with two WindScanners in an open-jet wind tunnel equipped active grid, range different turbulent conditions. A hot-wire anemometer is used as reference to assess lidar's statistics, time series spectra. In addition evaluating correlation between root-mean-square error (RMSE) on speed, compared modelled spectrum. spectral applied frequency domain, using Lorentzian filter combination Taylor's frozen hypothesis probe length averaging effect added white noise term, evaluated qualitatively matching measurement High goodness-of-fit coefficients low RMSE values hot wire WindScanner were observed series. showed inverse relationship prevalent intensity flow cases comparable power shape. Larger structures can be captured more accurately lidar, whereas small-scale are partly filtered out result volume effect. It demonstrated that accurate way define cut-off at which starts deviate from coherence drops below 0.5. coherence-based increases linearly mean speed generally order magnitude lower than equivalent frequency, estimated according simple based full width half maximum (FWHM) laser beam along line sight assuming hypothesis. convincing match found various cases, confirmed deviation higher analytically explained Lorentzian-shaped function measurement. Although models developed basis measurements, they should applicable atmospheric boundary layer field well.