New parameterization of wave-current interaction used in a two-way coupled model under typhoon conditions

Abstract

The two important upper ocean physical processes, i.e., radiation stress and wave-induced mixing effects, have not been simultaneously taken into consideration in the wave-current coupled parallel run models. Under the current formulations, neither the effect of stratification nor the error during computation is fully suggested. A new simplified parameterization scheme combining wave radiation stress with wave-induced mixing is introduced into a coupled model which consists of wave (WAVEWATCH Ⅲ) and current (POM) model, and typhoon KAEMI (2006) is taken as the example to carry out four sets of experiments. The numerical experiments show that the turbulence enhanced by the wave-induced mixing in mixing layer transfers momentum and heat into down water layers, but in general, does not regularly change surface currents. The wave radiation stress transfers momentum horizontally, and thus it changes horizontal currents regularly. When both physical processes are included in this coupled model, two effects are superposed in the simulation. As an important dynamic factor, the current affects the significant wave height and its distribution, which transfers horizontal momentum and makes significant wave height much higher in the present study. Furthermore, the current vector rotates clockwise at the time of the 48th hour due to the inertial oscillation probably being the signal of wave-current interaction amplified by the typhoon approaching.