Zusammenfassung: | |
Dual-Doppler lidar has become a useful tool to investigate the wind-field structure in two-dimensional planes. However, lidar pulse width and scan duration entail significant and complex averaging in the resulting retrieved wind-field components. The effects of these processes on the wind-field structure remain difficult to investigate with in situ measurements. Based on high resolution large-eddy simulation (LES) data for the surface layer, we performed virtual dual-Doppler lidar measurements and two-dimensional data retrievals. Applying common techniques (integral length scale computation, wavelet analysis, two-dimensional clustering of low-speed streaks) to detect and quantify the length scales of the occurring coherent structures in both the LES and the virtual lidar wind fields, we found that, (i) dual-Doppler lidar measurements overestimate the correlation length due to inherent averaging processes, (ii) the wavelet analysis of lidar data produces reliable results, provided the length scales exceed a lower threshold as a function of the lidar resolution, and (iii) the low-speed streak clusters are too small to be detected directly by the dual-Doppler lidar. Furthermore, we developed and tested a method to correct the integral scale overestimation that, in addition to the dual-Doppler lidar, only requires high-resolution wind-speed variance measurements, e.g. at a tower or energy balance station.
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Lizenzbestimmungen: | CC BY 4.0 Unported - https://creativecommons.org/licenses/by/4.0/ |
Publikationstyp: | Article |
Publikationsstatus: | publishedVersion |
Erstveröffentlichung: | 2015 |
Schlagwörter (englisch): | Coherent structures, Dual Doppler, Large-eddy simulation, Lidar, Doppler effect, Large eddy simulation, Wavelet analysis, Wind, Coherent structure, Correlation lengths, Dual-Doppler-lidar, In-situ measurement, Reliable results, Two dimensional plane, Virtual measurements, Optical radar, boundary layer, Doppler lidar, surface layer, wind velocity |
Fachliche Zuordnung (DDC): | 530 | Physik |
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