Effect of wave-dependent mechanisms on storm surge and current simulation during three extreme weather systems

The wave effect is crucial to coastal ocean dynamics, but the roles of the associated wave-dependent mechanisms, such as the wave-enhanced surface stress, wave-enhanced bottom stress, and three-dimensional wave force, are not yet fully understood. In addition, the parameterizations of each mechanism vary and need to be assessed. In this study, a coupled wave–current model based on the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) model system was established to identify the effect of the wave-dependent mechanism on storm surges and currents during three typical extreme weather systems, i.e., cold wave, extratropical cyclone, and typhoon systems, in a semienclosed sea. The effects of the three coupled mechanisms on the surface or bottom stress, in terms of both magnitude and direction, were investigated and quantified separately based on numerical sensitivity analysis. A total of seven parameterizations is used to evaluate these mechanisms, resulting in significant variations in the storm surge and current vectors. The similarities and differences of the wave-induced surge and wave-induced current among the various mechanisms were summarized. The change in the surface stress and bottom stress and the excessive momentum flux due to waves were found to mainly occur in shallow nearshore regions. Optimal choice of the combination of parameterization schemes was obtained through comparison with measured data. The wave-induced current in the open waters with a deep-water depth and complex terrain could generate cyclonic or anticyclonic current vorticities, the number and intensity of which always increased with the enhanced strength and rotation of the wind field increased. Significance Statement Waves induced by extreme weather systems can significantly modulate the storm surge and current field. Previous studies have developed different parameterizations for each physical mechanism. In this study, we aimed to separate and quantify the contribution of the wave-dependent mechanisms with typical parameterizations for storm surges and currents during three types of weather systems. The prediction of wave-induced surges in nearshore regions is critical especially during extreme weather systems and has diverse practical applications in ocean engineering. Through comparison with measured data, the best combination of parameterizations was identified, which could be helpful for regional disaster warning and management.