Buoy-Based Observations of the Wind Profile and Associated Conditions off the U.S. East Coast over an Annual Cycle

Pacific Northwest National Laboratory (PNNL) operates two lidar buoys as part of the U.S. Department of Energy’s (DOE’s) effort to advance the development of offshore wind energy. The buoys provide wind profiles and supporting meteorological and oceanographic information, which previously have not jointly been available over multiple seasons in the U.S. The motion-compensated lidars provide wind profiles up to 200 m above the ocean surface, which is well above hub height for wind turbines currently planned for deployment. Complementary observations from the buoys include surface winds and temperature, sea surface temperature, the two-dimensional wave spectrum, and current profiles from an acoustic Doppler profiler.

The buoys have each completed a full deployment spanning more than an annual cycle. One was deployed 42 km east of Virginia Beach, Virginia from 12 December 2014 through 15 June 2016, and the other was deployed 5 km east of Atlantic City, New Jersey from 4 November 2015 through 3 February 2017. During their deployments, the buoys were exposed to a wide variety of atmospheric conditions, ranging from stable summertime stratification through tropical storms to wintertime cold air outbreaks. These conditions represent most of the spectrum of atmospheric conditions that will affect wind-turbine power production and structural loading in the U.S. The data set from these systems also allows investigation of the surface physical processes affecting the shape of the wind profile and provides a new, unique opportunity to validate numerical weather predictions models for hub-height winds offshore.

We have completed an initial analysis of the observations collected by the buoys. In this presentation, we will show observed annual means and seasonal variability of the offshore wind resource together with corresponding sea and surface meteorological conditions that affect the wind profile. We will also contrast near-shore (Atlantic City) conditions with those found farther offshore (Virginia) and discuss the degree to which these various conditions may cause departures from conventionally used power-law or log-law wind profile shapes.