SPATIAL EVOLUTION OF THE FREQUENCY DISTRIBUTION OF DISSIPATION AND IMPLICATIONS ON FREQUENCY DOMAIN MODELING

The evolution of the frequency dependence of dissipation coefficient alpha(n) of shoaling and breaking waves is investigated. Prior studies have established the observation of and physical reasoning behind, alpha(n) similar to f(2), or that the dissipation should be weighted as the square of the wave frequency in the spectrum. A recent study, however, showed that this weighting evolves over the shoaling and breaking zone, with alpha(n) similar to f(2) acting as an inner surf zone asymptote. Parameterization of the evolution of the weighting as a function of depth brings forward several questions, the most important being whether the sum of individual breaking events is equivalent to the total dissipation as described by lumped parameterizations. Overall generality of the parameterizations will require more data to establish.