INSIGHT INTO WESTERN PACIFIC CIRCULATION FROM SOUTH CHINA SEA CORAL SKELETAL RADIOCARBON

The trajectory of the Kuroshio, the western boundary current in the north Pacific, influences regional climate. It intrudes into the South China Sea (SCS) through the Luzon Strait, resulting in the exchange of water, nutrients, heat, and salt between the Pacific and SCS. It has been reported that the trajectory of the Kuroshio has varied with decadal climate changes. However, there has been no report of an observation-based estimate of the variation in the Luzon Strait transport. Here, a 50-year, high-resolution coral skeletal radiocarbon (Delta C-14) dataset from 1946 to 1994 is reported from Currimao, northwest of Luzon Island. Delta C-14 has been used as a sensitive tracer of seawater, and our data indicates a significant increase in Delta C-14 from 1946 to 1994 related to atmospheric nuclear bomb testing, with more rapid increase in the SCS than in the Pacific. The unusual, rapid Delta C-14 increase in the 1950s found in our SCS corals together with seasonal variation in Delta C-14 will helps constrain physical oceanographic models for the western Pacific, including the SCS.