Preprints
https://doi.org/10.5194/wes-2021-75
https://doi.org/10.5194/wes-2021-75

  23 Aug 2021

23 Aug 2021

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

Turbulence in a coastal environment: the case of Vindeby

Rieska Mawarni Putri1, Etienne Cheynet2, Charlotte Obhrai1, and Jasna Bogunovic Jakobsen1 Rieska Mawarni Putri et al.
  • 1Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger, Norway
  • 2Bergen Offshore Wind Centre (BOW) and Geophysical Institute, University of Bergen, 5007 Bergen, Norway

Abstract. Turbulence spectral characteristics for various atmospheric stratifications are studied using the observations from an offshore mast at Vindeby wind farm. Measurement data at 6 m, 18 m and 45 m above the mean sea level are considered. At the lowest height, the normalized power spectral densities of the velocity components show deviations from Monin-Obukhov similarity theory (MOST). A significant co-coherence at the wave spectral peak frequency between the vertical velocity component and the velocity of the sea surface is observed, but only when the significant wave heights exceed 0.9 m. The turbulence spectra at 18 m generally follow MOST and are consistent with the empirical spectra established on the FINO1 offshore platform from an earlier study. The data at 45 m is associated with a high-frequency measurement noise which limits its analysis to strong wind conditions only. The estimated co-coherence of the along-wind component under near-neutral atmosphere matches remarkably well with those at FINO1. The turbulence characteristics estimated from the present dataset are valuable to better understand the structure of turbulence in the marine atmospheric boundary layer and are relevant for load estimations of offshore wind turbines. Yet, a direct application of the results to other offshore or coastal sites should be exercised with caution, since the dataset is collected in shallow waters and at heights lower than the hub height of the current and the future state-of-the-art offshore wind turbines.

Rieska Mawarni Putri et al.

Status: open (until 04 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wes-2021-75', Anonymous Referee #1, 21 Sep 2021 reply

Rieska Mawarni Putri et al.

Rieska Mawarni Putri et al.

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Short summary
Over the past years, offshore wind energy is considered as a reliable option for renewable energy and has caught the attention of many. The development and the deployment of wind turbines with a rotor size of twice the length of a football field on the ocean, motivate the thorough studies of wind characteristics in the ocean. Getting robust knowledge of wind behaviours over the ocean might improve the overall wind turbine's reliability and thus reduces its maintenance cost during its operation.