The influences of the Kuroshio on wave characteristics and wave energy distribution in the East China Sea

In the present study, current effects on waves (CEW) in a strong western boundary current area is investigated. An analytical formula is first derived to address how the kinematic parameters of currents affect wave variations: strain rate, divergence and deformation rate. The formula is applied to numerical wave solutions in the East China Sea (ECS), where the Kuroshio flows through. It is found that modeled wave heights and wave periods with and without the CEW are of significant differences in the Kuroshio area and also carry strong seasonality. In January, when the wave direction is against the Kuroshio, wave heights and periods with the CEW are significantly higher and longer than those without the CEW, while the opposite is noted in July when the wave direction is in the same as the current. The wave energy is also greatly enhanced (lessened) along the Kuroshio axis in January (July), due to the CEW. The analysis of the model results also shows that different terms in the CEW dominate in different seasons. In January, the wave variation caused by the CEW is due to the deformation rate of the current velocity, while in July, it is caused by the strain rate of current velocity. The influence of the CEW on the waves in the Kuroshio region is about 10–20%.