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Estimating Atmospheric Boundary Layer Turbulence in the Marine Environment Using Lidar Systems with Applications for Offshore Wind Energy

Praneeth Gurumurthy, S.M., 2021
Anthony Kirincich, Advisor

Estimating turbulence in the marine-atmospheric boundary layer is critical to many industrial, commercial and scientific fields, but of particular importance to the wind energy industry. Turbulence in the atmospheric boundary layer is estimated within the wind energy industry as Turbulence Intensity (TI) and Turbulent Kinetic Energy (TKE). Traditional in-situ methods to measure turbulence are extremely difficult to deploy in the marine environment, resulting in dependence on Doppler lidars. Lidars have shown to reliably estimate the wind speed and atmospheric turbulence while being cost effective and easily deployable.

In this thesis, the ability of lidars to measure turbulence up to a height of 200 m above mean sea level in the marine-atmospheric boundary layer was tested. Lidar-based TI and TKE were estimated by three methods using observations from a highly validated lidar system. Convective periods were found to have higher turbulence at all the heights compared to stable conditions, while mean wind speed and shear were higher during stable conditions. During highly turbulent events, TKE increased more strongly with height. All the three lidar-based TKE methods tested corresponded closely to independent estimates, and differences between the methods were small relative to the temporal variability of TKE observed at the offshore site.