Effects of the deep-water wave breaking dissipation on the wind-wave modelling in the Irish Sea

A numerical study of the effect of the deep-water wave breaking on the simulation of wind-waves in the Irish Sea region during some North Hemisphere winter months (January-February 2003) was carried out. A new formulation that takes into account the nonlinear effect of wave groups on the onset of wave breaking [Alves, J.H.G.M., Banner, M.L., 2003. Performance of a saturated-based dissipation-rate source term in modeling the fetch-limited evolution of wind waves. J. Phys. Oceanogr. 33, 1274-1298.] has been implemented and tested in a third-generation wave model. Its effect is assessed against the standard WAM Cycle 4 formulation and observations in the Irish Sea. The integrated spectral parameters computed by the new implementation of wave breaking tend to be larger (between 10% and 15% for significant wave height and mean period) than those computed by the standard formulation of WAM, especially on the eastern coast of the Irish Sea. It is found that, in the Liverpool Bay area, the only possibility for the waves to resuspend sediment is the occurrence of northwesterly wind conditions. In these situations fetch-limited growth is observed and both standard and new implementations provide similar results. In the southern Irish Sea, stronger mixed sea-swell conditions are predicted by the new formulation, which may have an impact in the description of the areas susceptible to sediment resuspension.