Quantification of errors in profiling lidar-based turbulence measurement using a large-eddy simulation

Profiling lidars are considered as a cost-effective alternative to meteorological masts (met-masts) for wind resource assessment at prospective wind energy sites. Numerous field campaigns have demonstrated good agreement between mean wind speeds derived from lidar measurements and those obtained from cup or sonic anemometers mounted on met-masts. However, lidar-derived turbulence intensity (TI) often exhibits varying levels of discrepancy, influenced by both site characteristics and measurement height. Profiling lidars commonly utilize the Doppler Beam Swinging (DBS) technique to reconstruct three-dimensional wind velocity vectors from line-of-sight wind speed measurements. This method typically relies on four or five beams and assumes horizontal homogeneity—a key source of error known as interbeam error. In field conditions, it is challenging to isolate this error from other contributors, such as intrabeam error. To address this limitation, the present study employs large-eddy simulations (LES) of the atmospheric boundary layer to emulate a virtual profiling lidar and quantify the impact of interbeam error on turbulence intensity estimates. The analysis explores the influence of different elevation angles and varying numbers of beams per DBS cycle. Ultimately, the study aims to develop a correction framework based on turbulence modeling to enhance the accuracy of lidar-based turbulence measurements.