Characterization of Uniform Momentum Zones in Atmospheric Boundary Layer Using Lidar Measurements
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Wind velocity measurements have been performed with a scanning Doppler wind LiDAR in order to characterize the morphology of the turbulent velocity field within the atmospheric surface layer (ASL). This experiment has been carried out at the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility, located at the U.S. Army Dugway Proving Ground (DPG) center in the western salt flats of Utah. The data analysis is focused on a data-set collected under near-neutral ASL stratification, with low-variability of the mean wind direction and with a good statistical convergence. The wind LiDAR has provided data throughout the ASL height, vertical resolution of about 1 m and temporal resolution of 1 second, which represent great features to investigate ASL turbulence at very high Reynolds numbers (Reτ ≈ O(106)). This study focuses on the detection and characterization of the turbulent/non-turbulent interface (TNTI) of the boundary layer, with special attention on the inclination of the TNTI and its connection with the morphology of large-scale coherent structures. Analyzing the turbulent region of the boundary layer flow, we use the instantaneous peak-detection method to characterize uniform momentum zones (UMZs). The variability of the height of the TNTI is related with a different number of UMZs, thus to different turbulent dynamics.