Observations of the Response of Sea Waves to Veering Winds

Abstract

A data-adaptive technique, the iterative maximum likelihood method, is used to estimate directional wave spectra from data collected by three pitch-and-roll buoys, during two turning wind events of the CASP 86 experiment. A relaxation coefficient is estimated for the response of both the mean wave direction for each frequency band and the main wave direction of the wind sea spectrum to a change in wind direction. The values of the coefficients are found to be consistent with each other, and within the scatter of previous estimates. Also, a definite correlation is established between the wave rms angular spread and the rate of change of wind direction. Finally, the shapes of the estimated directional distributions are tested for symmetry and unimodality. A significant proportion of the estimated distributions are found to be neither unimodal nor symmetric.