ABSTRACT
Keywords Time-frequency analysis techniques, Hilbert spectral analysis, empirical mode decomposition, irregular water waves, perturbation expansion approach, rogue waves, wave breakdown and modulation, wave self-focusing
A significant number of reported damages to ships and offshore structures suggest the existence of rogue waves (or freak waves), which are characterized by single exceptional large wave heights [1]. Rogue waves are defined as transient waves, existing only in one specific location in one particular instant in time. The assumption that these waves occur is preliminary, based on superposition of an infinite number of linear (free) wave components that coincide in phase during storm events (see e.g.: [2], [3], or [4]). Other attempts to explain them focus on wave-current interaction processes as a possible mechanism to generate or to enlarge the possibility of those abnormal events [5].
