Effect of Kuroshio Intrusion and Eddy Variability on the Luzon Strait

Water mass exchange induced by Kuroshio and eddies in the Luzon Strait are investigated using temperature–salinity data from available profiling float and hydrographic measurements. To qualitative analysis, trajectories of mesoscale eddies around the Luzon Strait region are investigated by using sea surface height anomaly by satellite altimeters. To quantitative analysis, Area, relative vorticity, nonlinearity parameter, amplitude, central velocity, lifetime, propagation pathway and kinetic energy of eddies are determined by the integration filtering algorithm. The spatial and temporal characteristics of eddies are also revealed by the automatic eddy tracking method. Both the cyclonic and anticyclonic eddies propagate westward to close Luzon Strait and interactive with the Kuroshio. It is found that in the Luzon Strait region, most of eddies decay and are carried northward along the Kuroshio path, and some of the eddies could pass through the gap between the North Pacific and the South China Sea. Although eddies could not be kept tracking while passing through the Luzon Strait, eddies located at two sides of the Luzon Strait are highly correlated. It seems that the drift of eddies is crucially affected by nonlinear first-mode baroclinic Rossby waves. While loop current events, some of eddies coalesce with the Kuroshio loop. It is also suggested that coalescence may trigger the variation of the Kuroshio in the Luzon Strait region.