Boundary-Layer Wind and Turbulence Retrieval from Doppler Wind Lidar for UAM Applications

Doppler wind lidar has recently seen rapidly increasing utilization as an observational instrument capable of continuously retrieving high-resolution vertical profiles of wind. However, the accuracy of the retrieved wind vectors can vary depending on the scanning strategy and data processing configurations. In this study, algebraic algorithms for retrieving wind vectors from line-of-sight velocities observed by a vertically profiling lidar are presented. The performance of each algorithm is evaluated through comparisons with wind vectors derived from GPS-tracked radiosonde observations. In addition, the utility of wind lidar observations is verified by comparison with wind profiler measurements for cases characterized by pronounced local variability.

Differences in wind speed depending on the selected azimuth angles within a single scan cycle violate the assumption of a homogeneous wind field required for height-resolved wind vector retrieval. From another perspective, this suggests the presence of atmospheric turbulence that disrupts the homogeneity of the flow. Using u, v, and w wind components retrieved at approximately 2.3-s intervals, turbulence intensity, momentum flux, and turbulent kinetic energy are estimated and compared with results obtained from a 20-Hz three-dimensional ultrasonic anemometers installed on a 300-m meteorological tower using the eddy correlation method. The two sets of results show very good agreement.

These findings demonstrate that Doppler wind lidar can effectively capture the vertical structure of the atmospheric boundary layer and provide critical hazardous-weather information essential for urban air mobility (UAM) operations. Furthermore, the results highlight the need to reconsider quality control procedures for spectral data, as enforced symmetry checks and corrections may remove genuine turbulent components. Further systematic investigation is required to better understand the impacts of spectral quality control procedures on both the representation and retrieval of atmospheric turbulence.