The South China Sea Throughflow (SCSTF) serves as a critical oceanic conveyor belt for heat and freshwater, mediating water exchanges between the South China Sea (SCS) and the Pacific and Indian oceans while regulating key processes such as heat and salt budgets, eddy activities, and marine biogeochemical cycles. It also plays a pivotal role in modulating the Indonesian Throughflow (ITF) and shaping climate variability across the Indo-Pacific. However, long-term direct observational data of the...