Swell and sea characteristics along the south-west coast of India during the monsoon

Swell and wind–seas generally co-exist in the open ocean, and are often difficult to segregate. Swell and wind–sea characteristics of observed wave spectra at off-Kochi, located along India's south-west coast in the Arabian Sea during the south-west monsoon are presented. This paper attempts to split the observed wave spectra into individual wave partitions, thereby enabling the computation of integral wave parameters of each partition. The spectra with five partitions is found occur more frequently in the considered season. To extract wind–sea and swell information from the observed directional spectrum, a consistent overshooting phenomenon (OP), Modified Overshooting phenomenon (MOP) and Wave age (WA) method are employed in each partition. The results show a prevalence of mixed sea states. An analysis from WA method shows the absence of young wind seas. The derived wind–wave parameters of the spectral partitioning algorithm agree well with Toba's 3/2 law with a good correlation. The effectiveness of interaction between the derived swell and sea components is discussed through nonlinear interactions that are occurring between the set of four waves.