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Towards improved turbulence estimation with Doppler wind lidar velocity-azimuth display (VAD) scans

Wildmann, Norman and Päschke, Eileen and Roiger, Anke and Mallaun, Christian (2020) Towards improved turbulence estimation with Doppler wind lidar velocity-azimuth display (VAD) scans. Atmospheric Measurement Techniques, 13 (8), pp. 4141-4158. Copernicus Publications. doi: 10.5194/amt-13-4141-2020. ISSN 1867-1381.

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Official URL: http://dx.doi.org/10.5194/amt-13-4141-2020

Abstract

The retrieval of turbulence parameters with profiling Doppler wind lidars (DWLs) is of high interest for boundary layer meteorology and its applications. DWLs provide wind measurements above the level of meteorological masts while being easier and less expensive to deploy. Velocity-azimuth display (VAD) scans can be used to retrieve the turbulence kinetic energy (TKE) dissipation rate through a fit of measured azimuth structure functions to a theoretical model. At the elevation angle of 35.3° it is also possible to derive TKE. Modifications to existing retrieval methods are introduced in this study to reduce errors due to advection and enable retrievals with a low number of scans. Data from two experiments are utilized for validation: first, measurements at the Meteorological Observatory Lindenberg–Richard-Aßmann Observatory (MOL-RAO) are used for the validation of the DWL retrieval with sonic anemometers on a meteorological mast. Second, distributed measurements of three DWLs during the CoMet campaign with two different elevation angles are analyzed. For the first time, the ground-based DWL VAD retrievals of TKE and its dissipation rate are compared to in situ measurements of a research aircraft (here: DLR Cessna Grand Caravan 208B), which allows for measurements of turbulence above the altitudes that are in range for sonic anemometers. From the validation against the sonic anemometers we confirm that lidar measurements can be significantly improved by the introduction of the volume-averaging effect into the retrieval. We introduce a correction for advection in the retrieval that only shows minor reductions in the TKE error for 35.3° VAD scans. A significant bias reduction can be achieved with this advection correction for the TKE dissipation rate retrieval from 75° VAD scans at the lowest measurement heights. Successive scans at 35.3 and 75° from the CoMet campaign are shown to provide TKE dissipation rates with a good correlation of R>0.8 if all corrections are applied. The validation against the research aircraft encourages more targeted validation experiments to better understand and quantify the underestimation of lidar measurements in low-turbulence regimes and altitudes above tower heights.

Item URL in elib:https://elib.dlr.de/135709/
Document Type:Article
Title:Towards improved turbulence estimation with Doppler wind lidar velocity-azimuth display (VAD) scans
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Wildmann, NormanDLR, IPAhttps://orcid.org/0000-0001-9475-4206
Päschke, EileenDWD, MOL-RAOUNSPECIFIED
Roiger, AnkeDLR, IPAUNSPECIFIED
Mallaun, ChristianDLR, FXUNSPECIFIED
Date:4 August 2020
Journal or Publication Title:Atmospheric Measurement Techniques
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:13
DOI :10.5194/amt-13-4141-2020
Page Range:pp. 4141-4158
Publisher:Copernicus Publications
ISSN:1867-1381
Status:Published
Keywords:Lidar, wind profiling, turbulence
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Wind Energy
DLR - Research area:Energy
DLR - Program:E SW - Solar and Wind Energy
DLR - Research theme (Project):E - Wind Energy (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Transport Meteorology
Institute of Atmospheric Physics > Atmospheric Trace Species
Flight Experiments > Oberpfaffenhofen
Deposited By: Wildmann, Norman
Deposited On:05 Aug 2020 10:14
Last Modified:05 Aug 2020 10:14

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