The offshore wind resource and boundary layer structure

Coastal and offshore locales are favored regions for wind power utilization because of the generally high wind resource, proximity to major load centers, and existing transmission infrastructure. However, because of the dearth of long-term high quality observations available over the offshore waters, comparatively little is known about the three-dimensional structure of the lowest 200 m of the marine boundary layer, especially as it relates to the determination of the wind resource and turbulence effects within, above, and below the rotor plane. Recent field observations and modeling studies have shown the existence of low-level jets, or sheet-like structures, just offshore of the mid-Atlantic and northeastern U.S. coastal regions, prime areas for the development of wind power production facilities. These structures feature wind speed maxima between 70 and 120 m above the surface (Figure 1), well within the typical rotor plane of the larger wind turbines proposed for the offshore waters. Therefore, the purpose of this presentation is to show, through modeling studies and recent field observations, the spatial and temporal characteristics of the LLJs, their climatology, and their potential effect on wind resource assessment campaigns, turbine design, and load matching.