Measurements of a Mid-Atlantic Low-Level Jet Offshore Using a Pulsed Doppler LIDAR from a Moving Platform

Investments in renewable energy are increasing due to climate change and opportunities for economic growth. Wind energy in particular, has become a leader of renewable energy owing to an abundant amount of wind resource, and on- and offshore research through numerical modeling. Most of the numerical studies however, interpret winds with coarse resolution, and thus neglect the variability of winds at the scale of a turbine. As a result, little is understood about how local changes in wind impact wind farm power performance and turbine degradation. To overcome this obstacle, long-term measurements of wind and turbulence profiles are required to determine locations best suited for wind farm installations. A well-researched solution to determine highly resolved measurements of wind is through an application of a Doppler LIDAR (LIght Detection and Ranging). The majority of studies employing Doppler LIDARs have demonstrated the instrument's ability to accurately measure wind and turbulence throughout the scale of a turbine. As a result, Doppler LIDARs have become a prevalent measurement tool for wind energy purposes. This research explores the versatility of a Doppler LIDAR by investigating its measurement performance on offshore platforms. A case study is presented showing results collected while underway on a research vessel in Maryland's Wind Energy Area (MDWEA) during July 19th, 2013. A motion compensation algorithm was constructed to remove rotational and translational motions of the research vessel from the wind data. Corrections to wind and turbulence during July 19th reveal a Low-level jet (LLJ) with strong shear and intermittent “turbulence bursts”. The majority of the turbulence generated occurred during the jet's collapse around 03:00 EST. Confirmation of the jet's intensity and dissipation are corroborated with WRF (Weather Research and Forecasting) models and an onshore profiler at Cambridge, Maryland.