Characteristics of Offshore Positive Wind Shear Coefficients Under Different Atmospheric Stability Conditions: A Case Study of the Zhuanghe Offshore Area, China

Abstract

Wind shear coefficients (WSCs) are fundamental parameters for wind resource assessment, wind turbine design, and offshore wind farm operation. This work focuses on positive wind shear coefficients (WSCs); hereafter, WSC refers exclusively to positive-value wind shear coefficients derived from positive shear profiles. However, the characteristics of positive WSCs in the offshore waters of Zhuanghe have not yet been systematically investigated. In this study, two years of in situ observational data (2015–2017) were analyzed to characterize the temporal variability of positive WSCs under different atmospheric stability conditions. The results indicate that the atmospheric boundary layer in the study area exhibits pronounced seasonal and diurnal variations in stability, with stable and unstable conditions showing a distinct annual cycle. Increasing wind speed promotes neutral conditions as mechanically generated turbulence becomes dominant over buoyancy effects. The WSC ranges from 0.01 to 0.32 and exhibits pronounced seasonal and monthly variability. Under neutral and unstable atmospheric conditions, the diurnal variation in WSC is relatively consistent among different measurement heights, whereas stable conditions produce appreciable vertical differences in WSC throughout most of the year. These findings improve our understanding of offshore wind shear characteristics across various atmospheric stability regimes. Furthermore, they offer valuable guidance for offshore wind resource assessment, wind profile modeling, and the overall design and operation of wind farms in the Zhuanghe region.

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