Seasonal and interannual variations in material transport in the Korea Strait originating from the Taiwan Strait

The Tsushima Warm Current (TSWC), which flows through the Korea Strait (KS), is crucial in transporting nutrient-rich, warm, and saline water to the East/Japan Sea. Understanding the origins and variability of the TSWC is essential because of its significance in Northwestern marginal seas. Although previous studies have suggested that the Taiwan Strait (TS) partially originates from the TSWC, the seasonal and interannual variability in the material connectivity between the TS and KS remains poorly understood. In this study, we investigated this variability using a Lagrangian particle-tracking system and a three-dimensional numerical model. The model results showed that particles originating from TS passed through KS most frequently in August. Furthermore, particles traveling from the TS to KS exhibited distinct interannual variability. Composite analysis indicated that southerly winds increased sea surface height (SSH) in the southwestern East China Sea (ECS) shelf region via surface Ekman transport, weakening cross-shelf offshore currents and preventing particles from being transported offshore. Empirical Orthogonal Function (EOF) analysis indicated that the interannual variability of southerly winds over the ECS was associated with variations in SSH in the southwestern shelf region, thereby influencing material transport from the TS to the KS.