Turbulence characterization in near-coastal environment using triple short-range lidars and mast anemometry

Abstract

Single- and two-point turbulence spectra derived from wind velocity measurements at a near-coastal site in northern Germany are analysed across a wide range of atmospheric-stability conditions. Spectral estimates are obtained from sonic and cup anemometer data, as well as from velocity time series reconstructed using a system of three synchronized short-range scanning lidars. A high level of agreement is observed at low and intermediate frequencies, with all measurement systems capturing key spectral features, including a plateau under convective conditions and a spectral gap in stable stratification. At higher frequencies, discrepancies arise due to spatial and temporal averaging effects inherent in the lidar and cup anemometer measurements. Spatial coherence estimates are comparatively less affected by these limitations and show high agreement, with exceptions. The synchronized lidar system is found to be highly suitable for coherence analysis, offering flexibility in terms of separation direction, distance, and height. Empirical models are fitted to the auto-spectra and coherence estimates to derive the model parameters as functions of atmospheric stability.