Impact of a coupled ocean wave–tide–circulation system on coastal modeling

The impact of a coupled ocean wave–tide–circulation system on coastal modeling for wind waves, oceanic circulation, and water-mass simulation is investigated by coupling of two well-tested models: the third-generation wave model (WAVEWATCH-II) and the Princeton ocean model (POM). In this study, several numerical experiments in the Yellow and East China Sea (YECS) are performed for the ideal winter case and the typhoon Winnie case. In the coupled system, wind waves are influenced by both currents and sea level elevation induced by tides, storm surges, and oceanic circulation. Tides were the most influential factor in modulating mean wave characteristics in the YECS. The magnitude of the modulation of mean wave parameters at neap tides is found to be half that at spring tides. In the YECS the tides affect not only wind waves, but also seasonal circulation and water-mass distributions. Tides increase the bottom friction of the YECS significantly and this contributes to a change of winter current direction up to 60 °C in the YECS and a decrease of surface temperatures along the trough of the Yellow Sea up to 4 °C in winter. Tides in summer produce the strong vertical mixing in shallow regions. This leads to the formation of tidal fronts in a boundary between well-mixed and stratified regions and causes sea surface temperatures (SST) along the west coast of Korea decrease as much as 3 °C. Effects of ocean waves on coastal circulation and SST simulations are investigated considering wave-dependent stress, wave breaking parameterization, and Langmuir circulation under typhoon Winnie conditions. The results show that the wave-dependent stress, which is strongly dependent on wave age and relative position from storm center, as well as the wave breaking have the most significant impact on the SST distribution.