Posters

Abstract

Measuring high-quality wind in the hostile environment that is offshore presents many challenges that Floating Lidar Systems (FLS) are helping to overcome. One of the difficulties left to solve is the Turbulence Intensity (TI), which measurement by a lidar shows discrepancies compared to met mast-mounted anemometry. A key component of this discrepancy is the Horizontal Wind Speed (HWS) noise created by the buoy motion. Compensating for the buoy movements would thus help reduce the TI error and produce measurements equivalent to that of a fixed lidar. As lidars are commonly set to measure at several heights to obtain a detailed wind profile, the data quantity at each height can be another limitation for continuous wave (CW) lidars, as the amount of measured data points is inversely proportional to the number of heights set on the instrument. A lower number of points implies a higher vulnerability to motion, and therefore a more biased TI.   The goal of this analysis is twofold:  -    assess the impact of different Motion Compensation (MC) strategies applied to a buoy-mounted lidar compared to a reference met-mast data,  -    compare the MC data obtained from a multi-height and single-height configured lidar. Several new approaches to MC have been presented over the past few years, each with their own advantages and disadvantages. The model presented in this work is based on the 1 Hz wind data compensation using Euler angles obtained from an Inertial Measurement Unit (IMU). It ensures full traceability of the correction and is not environment dependant.  Green Rebel deployed a FLS at the National Offshore Anemometry Hub (NOAH) for a duration of 5 months (August to December 2025). The FLS had the following instruments: -    a CW lidar configured to measure at a single height (100 m AMSL), -    a CW lidar configured to measure at 12 different heights, -    one IMU, and -    a directional wave sensor. The NOAH mast is equipped with Class 1 cup anemometers mounted at 52 m, 69 m, 86 m, and 103 m above mean sea level (AMSL), as well as a CW lidar. For each HWS, at 100 m height, the uncorrected FLS TI values and those corrected by the MC for each lidar were compared against the mast-mounted anemometer TI. Additional comparisons of the HWS-MC between the single and multiple height buoy-mounted lidar are provided as well.