Separation of Wave Systems in Time Series of Combined Sea States

In some oceanographic applications it is necessary to separate the individual sea state components, or wave systems, that are present in complex wave conditions represented by multipeaked wave energy spectra. Later on, it may be required to realign the original sea states having only the calculated parameters of the splitted spectrum. As an example, this situation may arise when trying to make correlation between time evolution of the sea states with meteorological forcings. To solve this problem a method was developed to follow the time evolution of a given initial sea state using a mathematical tracking procedure. It is based in a “similarity index” between one point of the time series and three previous points. The criterion uses wave parameters Hs (significant wave height), Tp (spectral peak period) and Dir (spectral peak wave direction) to calculate the similarity index. The method selects points that have the highest similarity index as a part of the same type of spectral component, following the time sequence of waves.