Unveiling Offshore Wind Resources during the WFIP-3 Field Campaign: Preliminary Results from One Ground-Based Scanning LiDAR

With 56.3 GW of expected wind capacity to be installed in 2024, offshore wind energy is rapidly becoming one of the most viable renewable energy sources leveraged to reach the goal of decarbonizing the U.S. electric grid by 2035. For this reason, in the last few decades, several numerical tools have been refined to better predict the offshore wind resources carried by turbulent motion of different sizes, from the largest meteorological scales (on the order of 1 km) down to the smallest energy-containing turbulent scales (~10 m). However, the real prediction capabilities of these complex numerical models must be assessed against field observations collected at sites of interest for the wind energy stakeholders. Thus, in 2024 the U.S. Department of Energy sponsored the third Wind Forecast Improvement Project (WFIP-3) aimed at assessing the wind resources along the U.S. Northeast coast. This multi-institutional campaign relies on field observations collected both onshore and offshore by several ground-based instruments over the course of two years to assess state-of-the-art numerical models and, at the same time, to shed a new light on the complex flow phenomena (e.g. low-level jets, gravity waves, wave roughness etc.) characterizing sea-to-land transition sites.

One of the most widely used sensing devices is the Doppler scanning wind LiDAR, which is a laser-based instrument able to resolve spatio-temporal turbulent coherent motions with high resolution (~20 m space resolution and ~1 Hz sampling rate, respectively). In this work, preliminary results from one scanning LiDAR (model Streamline XR+, manufactured by Lumibird), obtained at one onshore WFIP-3 site in Rhode Island, U.S.A., are presented. An overview of the chosen scanning strategy is provided, aimed at resolving targeted flow features with high statistical accuracy. Specifically, three-dimensional coherent motions (e.g. topography-induced high- and low-momentum regions close to the ground) are retrieved from LiDAR 3D volumetric scans, 2D spatial flow statistics during canonical and non-canonical (e.g. low-level jet) Atmospheric Boundary Layer (ABL) events are inferred from fast Range Height Indicator (RHI) scans, and finally, high-resolution turbulent motions are resolved from vertically pointing LiDAR scans. These measurements provide a direct estimate of the ABL height and the aerosol mixing properties over the sea-land transition under a wide range of thermal stability values.