Characterization of offshore vertical wind shear conditions in Southern New England

摘要

Vertical wind shears could have a significant effect on the energy produced by a wind turbine and on its loads. Although the development of several wind farms has been planned on the East Coast of the United States, there are no studies that characterize the vertical wind shear over this area. This study focuses on characterizing wind shears in the marine boundary layer in Southern New England and along the East Coast of the United States. The analysis looks at the statistical distribution of vertical wind shear values and at their associated meteorological conditions. The analysis relies on remote-sensing wind measurements and other meteorological data recorded at the Woods Hole Oceanographic Institution Air-Sea Interaction Tower located 3 km to the South of Martha's Vineyard, together with buoy measurements and ERA5 reanalysis data. This work shows that large vertical wind shear values (0.05 m/s/m) calculated using wind measurements at 60 and 53 m were often observed (approximate to 25.3% of all the valid wind profiles analyzed) for South-Westerly winds within a range of positive bulk Richardson numbers 0-0.1. These large-shear values are the result of the presence of a strong high-pressure system (Bermuda-Azores High) over the North Atlantic basin and low pressures over land, which result in warm Southerly winds flowing over the cold waters of the Labrador current. The power density computed considering the vertical wind shear by means of the rotor equivalent wind speed is 5.5% smaller than that considering wind speed measurements at 110 m only.