Wind speed profile dataset associated wit the LOLland offshore Lidar EXperiment (LOLLEX)

This repository contains NetCDF time-series data from the LOLland offshore Lidar EXperiment (LOLLEX), conducted from September 2022 to August 2023 in and around the Rødsand II offshore wind farm, south of Lolland, Denmark. The campaign used a crew transfer vessel as a mobile offshore measurement platform to collect Doppler wind lidar observations inside, near, and around the wind farm. The dataset supports the study “The LOLland offshore Lidar EXperiment (LOLLEX): A novel observational approach for the study of wind farm flow and entrainment” by Malekmohammadi et al. The campaign was designed to investigate atmospheric boundary-layer processes relevant to offshore wind-farm wake recovery, with particular focus on vertical momentum entrainment, turbulence, internal atmospheric waves, Kelvin–Helmholtz billows, and turbine-wake observations. The repository is organised into three folders. WindCube100S DBS NetCDF files Daily NetCDF files containing time series from the WindCube 100S scanning Doppler wind lidar operated in Doppler beam swinging (DBS) mode. Only the DBS scans from the WindCube 100S are included in this repository. Vertical zenith line-of-sight scans are provided in a separate repository. The files are provided in NetCDF-4 classic format and follow CF-1.8 metadata conventions. Each file contains one day of data on a one-dimensional time coordinate, expressed as seconds since 1970-01-01 00:00:00 UTC. The vertical coordinate z gives the measurement heights in metres, with 259 height levels in the daily DBS files. The posUnique coordinate identifies the unique scan positions used by the lidar, where 999 denotes vertical or other non-standard positions. The DBS zenith angle is stored as zen and is also provided as a global attribute, zenith_angle_deg. The WindCube 100S DBS files include uncorrected wind components u_uncorr, v_uncorr, and w_uncorr, together with the corresponding uncorrected wind direction dir_uncorr. Motion-corrected wind components are provided as u_corr, v_corr, and w_corr, with corrected wind direction stored as dir_corrected. The files also include carrier-to-noise ratio CNR, radial velocity vr as a function of height, scan position, and time, and the scan position recorded at each time step. These data provide high-vertical-resolution DBS wind-profile observations from the vessel-mounted WindCube 100S system. They are intended for analyses of offshore wind profiles, wind direction, signal quality, motion-correction effects, atmospheric boundary-layer structure, wind-farm wake behaviour, and entrainment-related processes. Users interested in the vertical zenith line-of-sight measurements should use the separate repository containing those scans. WindCubeV2 NetCDF files Daily NetCDF files containing time series from the WindCube V2 Doppler lidar wind profiler. The files are provided in NetCDF-4 classic format and contain one day of data on a one-dimensional time coordinate, expressed as seconds since 1970-01-01 00:00:00 UTC. The vertical coordinate z gives the measurement heights in metres, with 12 height levels available in the daily files. The posUnique coordinate identifies the unique scan positions used by the instrument, where 999 denotes vertical or other non-standard positions. The WindCube V2 data include uncorrected wind components u_uncorr, v_uncorr, and w_uncorr, together with the corresponding uncorrected wind direction dir_uncorr. Motion-corrected wind components are provided as u_corr, v_corr, and w_corr, with corrected wind direction stored as dir_corrected. The files also include carrier-to-noise ratio CNR, radial velocity vr as a function of height, scan position, and time, system temperature Temp, and the scan position variable position recorded at each time step. These data provide vertical profiles of wind speed, wind direction, radial velocity, signal quality, and temperature from the vessel-mounted WindCube V2 system. They are intended to characterise the flow conditions encountered during the campaign, support comparison with the scanning WindCube 100S measurements, and provide wind-profile information needed for analyses of offshore wind-farm wakes, atmospheric boundary-layer structure, and motion-corrected lidar observations from a moving vessel. Vessel position and motion NetCDF files Daily NetCDF files containing time series of vessel position, velocity, heading, and attitude data from the vessel IMU/GNSS system. The files are provided in NetCDF-4 classic format and follow CF-1.8 metadata conventions. Each file uses a one-dimensional time coordinate, expressed as seconds since 1970-01-01 00:00:00 UTC, with variables stored along the time dimension. The vessel position is given by longitude lon in degrees_east and latitude lat in degrees_north. Vessel translational motion is described by the SBG velocity components SBGVx, SBGVy, and SBGVz, provided in m s-1. Vessel attitude is described by roll, pitch, and yaw, provided in degrees. The files also include GPS_heading, provided in degrees. These data document the trajectory, heading, velocity, and orientation of the crew transfer vessel during the lidar measurements. They are used to identify periods when the vessel was in harbour, in transit, or operating inside or near the wind farm, and they provide the motion and position information needed to interpret the mobile lidar observations and to apply or assess motion-correction procedures. All files are provided as daily NetCDF files to facilitate time-based access, reproducible analysis, and integration with common atmospheric and wind-energy data-processing workflows. The data include periods when the vessel was located in harbour, in transit, and inside or near the Rødsand II wind farm. Data availability varies between instruments and dates because of campaign logistics, vessel operations, instrument status, and quality-control filtering. The dataset is intended for research on offshore wind-farm wakes, atmospheric boundary-layer dynamics, Doppler wind lidar measurements from moving platforms, motion correction, turbulence characterisation, and vertical momentum entrainment. Users should consult the associated paper for details on the campaign setup, instrument configuration, data processing, quality-control procedures, limitations, and example applications. When using this dataset, please cite both this Zenodo repository and the associated paper.