Influence of the Measurement Height on the Vertical Coherence of Natural Wind
Two years of sonic anemometer records, collected on the offshore platform FINO1 in the North Sea are used to study the vertical coherence of the along-wind and vertical wind components under near-neutral conditions. The goal is to assess the influence of the measurement height on the coherence estimates. For the data set considered, a 3-parameter coherence model, which depends explicitly on the measurement height and accounts for the limited dimensions of the eddies, is found to be more appropriate than the Davenport model or the uniform shear model to describe the vertical coherence. This is partly because the latter two models do not take into account the blockage effect by the sea surface. The computation of the joint acceptance function of a line-like vertical structure with the Davenport model and the 3-parameter coherence model suggests that the use of the latter model may substantially improve the design of high-rise wind-sensitive structures such as wind turbines.
KeywordsFull-scale Marine atmospheric boundary layer Coherence Turbulence Surface layer
The author would like to acknowledge the Federal Ministry for Economic Affairs and Industry and the Projektträger Jülich for funding the FINO project, and UL DEWI for providing the sonic data. Prof. Jasna Bogunović Jakobsen is gratefully acknowledged for her review of the manuscript. Thanks are also due to Prof. Joachim Reuder for his useful advice regarding the wind data analysis.
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