Role of JEBAR in Modulating the Pathways of Kuroshio Intrusion Into the South China Sea

Abstract The Kuroshio intrusion into the South China Sea (SCS) through the Luzon Strait (LS) exhibits three different paths—looping, leaping, and leaking. In this study, a high‐resolution Oceanic Regional Circulation and Tide Model is employed to investigate these pathways by calculating the Kuroshio SCS Index (KSI), coupled with a comprehensive diagnostic analysis of the vorticity balance to explore the controlling dynamic mechanisms. The results reveal that the KSI exhibits seasonal variations, with the leaping path predominantly occurring in summer, the looping path primarily prevailing in winter, and the leaking path mainly emerging in spring and autumn. The spatial distribution of the advection of geostrophic potential vorticity (APV) transport reveals two key regions within the LS that are critical to the Kuroshio intrusion into the SCS. The Joint Effect of Baroclinicity and Relief (JEBAR), serving as the dominating forcing term, balancing the APV term; its intensity is significantly affected by upstream Kuroshio transport (KT) via modulating the local horizontal density gradient: stronger KT homogenizes the water mass, weakening JEBAR and favoring the formation of the leaping path, while weaker KT enhances density–topography coupling, strengthens JEBAR, and promotes the formation of the looping path; intermediate conditions give rise to the leaking path. This study provides a general dynamic framework for understanding the multiple pathways of Kuroshio intrusion, offering insights into the circulation in the SCS.