Steepness of High Ocean Waves in Quasi-Determinism Theory

This paper investigates the steepness of large ocean waves. Different steepness and asymmetry parameters of the highest wave in a time series recorded in severe storms as well as nonlinearity of the records were investigated in Guedes Soares et al (2003, 2004). Here the steepness of high waves will be investigated by considering the ocean wave groups, both to the first and to the second order in a Stokes expansion, and some conclusions are obtained with wave data generated in an offshore basin. In particular, some parameters of wave steepness defined in Guedes Soares et al. (2004) are obtained with an analytical approach, by starting from the Boccotti’s linear Quasi- Determinism theory, including the second-order component derived by Arena (2005) for wave groups in undisturbed wave field. Furthermore, the wave field is analyzed in the space domain, to determine the actual steepness of the highest waves. These results, achieved starting from either the time or the space domain, will be analyzed for different wave spectra.