Nonlinear Parameters of Wave Distribution to Characterize Freak Waves

Abstract

This study is carried out to investigate the nonlinear characteristics of field observed wave data acquired in the southwestern sea of Korean peninsula for 3 years. It is aimed to identify the correlation between nonlinear parameters and freak wave occurrence, which may eventually lead to freak wave forecasting based on wave spectra in real sea. The nonlinear parameters of ocean waves of skewness, atiltness, kurtosis and spectrum band width et al. are analyzed, and their relevance with component wave characteristics of significant wave height, maximum wave height and so on is examined. It is evident that with an exception of kurtosis, the parameters describing nonlinear characteristics of observed wave spectrum are feebly related to occurrence of abnormal maximum wave height, namely freak event. The kurtosis, which is a degree of peakness of mode of surface elevation distribution, shows strong relevance with freak event and we suggest a logarithmic formulation describing their correlation based on field wave data.