Statistical properties of surface gravity waves and freak wave occurrence in crossing sea states

Statistical properties of surface waves and freak wave shapes in crossing sea states are systematically studied, and particularly a new index is proposed to measure the occurrence probability of extreme waves. The proposed new index is proven to be a more accurate indicator of freak wave occurrences in crossing sea states than the Benjamin-Feir index that has been widely applied for seas with single-peak spectra. Our work can shed light on the generation mechanism and negative impact of freak waves, and advance the development of warning systems for marine disasters.