Impact of Ocean Currents on Surface Waves Generated by Tropical Cyclone

Abstract

Accurate surface wave predictions under tropical cyclones require a coupled ocean–wave model, as the wave field can be strongly influenced by surface currents. In this study, the WAVEWATCH III wave model, coupled with the Modular Ocean Model 6, is used to examine the impacts of surface currents on deep-water waves forced by idealized tropical cyclones of varying size, intensity, and translation speed. The ocean model uses a mixing scheme that explicitly includes wave-induced Langmuir turbulence enhancement, resulting in reduced surface Eulerian currents that are more consistent with observations. The surface current introduced in the wave model is the sum of the surface Eulerian current and the enhancement of the dominant wave group velocity due to the nonlinear interaction with coexisting waves. Results across all cases show that maximum significant wave height is substantially overestimated, by up to ~9%, when the current effect is omitted. Wave simulations are also sensitive to how the surface current is specified, underscoring the importance of using an accurate upper-ocean mixing scheme and incorporating group velocity enhancement by coexisting waves into the wave model. Analysis further reveals that the wave height reduction arises primarily because dominant wave packets propagate faster and spend less time under strong wind. These findings demonstrate that proper representation of surface currents is critical for improving the accuracy of wave forecasts in tropical cyclone conditions.