Preprints
https://doi.org/10.5194/amt-2020-511
https://doi.org/10.5194/amt-2020-511

  18 Mar 2021

18 Mar 2021

Review status: this preprint is currently under review for the journal AMT.

The COTUR project: Remote sensing of offshore turbulence for wind energy application

Etienne Cheynet1,3, Martin Flügge2, Joachim Reuder1, Jasna B. Jakobsen3, Yngve Heggelund2, Benny Svardal2, Pablo Saavedra Garfias1, Charlotte Obhrai3, Nicolò Daniotti3, Jarle Berge3, Christiane Duscha1, Norman Wildmann5, Ingrid Husøy Onarheim4, and Marte Godvik4 Etienne Cheynet et al.
  • 1Geophysical Institute and Bergen Offshore Wind Centre, University of Bergen, Allegaten 70, N-5007 Bergen, Norway
  • 2NORCE Norwegian Research Centre AS, P.O. box 22 Nygårdsgaten 112, 5838 Bergen, Norway
  • 3Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger, Norway
  • 4Equinor ASA, Postboks 7200, 5020 Bergen, Norway
  • 5Institute of Atmospheric Physics, German Aerospace Center (DLR), Oberpfaffenhofen, 82234 Wessling, Germany

Abstract. The paper presents the measurement strategy and dataset collected during the COTUR (COherence of TURbulence with lidars) campaign. This field experiment took place from February 2019 to April 2020 on the southwestern coast of Norway. The coherence quantifies the spatial correlation of eddies and is little known in the marine atmospheric boundary layer. The study was motivated by the need to better characterize the lateral coherence, which partly governs the dynamic wind load on multi-megawatt offshore wind turbines. During the COTUR campaign, the coherence was studied using land-based remote sensing technology. The instrument setup consisted of three long-range scanning Doppler wind lidars, one Doppler wind lidar profiler and one passive microwave radiometer. Both the WindScanner software and Lidar Planner software were used jointly to simultaneously orient the three scanner heads into the mean wind direction, which was provided by the lidar wind profiler. The radiometer instrument complemented these measurements by providing temperature and humidity profiles in the atmospheric boundary layer. The preliminary results show an undocumented variation of the lateral coherence with the distance from the coast. The scanning beams were pointed slightly upwards to record turbulence characteristics both within and above the surface layer, providing further insight on the applicability of surface-layer scaling to model the turbulent wind load on offshore wind turbines.

Etienne Cheynet et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2020-511', Anonymous Referee #3, 15 Apr 2021
  • RC2: 'Comment on amt-2020-511', Jakob Mann, 06 Jun 2021

Etienne Cheynet et al.

Etienne Cheynet et al.

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Short summary
The COTUR campaign explored the structure of wind turbulence above the ocean to improve the design of future multi-megawatt offshore wind turbines. Deploying scientific instrument offshore is both a financial and technological challenge. Therefore, lidar technology was used to remotely measure the wind above the ocean from instruments located on the seaside. The experimental setup is tailored to the study of the spatial correlation of wind gusts, which governs the wind loading on structures.