COMPLEX ENVELOPE OF SURFACE GRAVITY-WAVES

The complex envelope function is presented as the natural analysis technique for wave records where the identification of wave groups is a dominant interest. Algorithms have been developed and confirmed for separation of the complex envelope function, estimation of the dominant frequency, and unwrapping of the phase function. Cross-correlograms and coherence spectra reveal a link between the envelope amplitude and phase traces that appears to be an intrinsic signature of wave groups. Nevertheless, the majority of the information in typical wave records can be categorized as linear and random, confirming the relative success of the Gaussian random wave model.