A new method for determining near-surface shear current profiles from wave measurements

We present a new inversion method for finding the near-surface shear current profile from measurements of the wave spectrum. The method extracts wavelength-dependent Doppler shift velocities of the wave celerity due to the subsurface current, and assigns effective depths to the shifts using an iterative technique. The method gives an improvement over existing state-of-the-art techniques for most current profiles, and is less sensitive to experimental noise. We apply the method to laboratory experimental results of waves generated atop vertically-sheared currents of various depth-dependence, where particle image velocimetry (PIV) is used as ‘truth’ data. We also investigate the use of the method in cases where the current profile is known for deeper depths, which greatly reduces the error in the inferred current profiles.