Surface current field and seasonal variability in the Kuroshio and adjacent regions derived from satellite-tracked drifter data

The multiyear averaged surface current field and seasonal variability in the Kuroshio and adjacent regions are studied.The data used are trajectories and (1/4)° latitude by (1/4)° longitude mean currents derived from 323 Argos drifters deployed by Chinese institutions and world ocean circulation experiment from 1979 to 2003.The results show that the Kuroshio surface path adapts well to the western boundary topography and exhibits six great turnings.The branching occurs frequently near anticyclonic turnings rather than near cyclonic ones.In the Luzon Strait, the surface water intrusion into the South China Sea occurs only in fall and winter.The Kuroshio surface path east of Taiwan, China appears nearly as straight lines in summer, fall, and winter, when anticyclonic eddies coexist on its right side;while the path may cyclonically turning in spring when no eddy exists.The Kuroshio intrusion northeast of Taiwan often occurs in fall and winter, but not in summer.The running direction, width and velocity of the middle segment of the Kuroshio surface currents in the East China Sea vary seasonally.The northward intrusion of the Kuroshio surface water southwest of Kyushu occurs in spring and fall, but not in summer.The northmost position of the Kuroshio surface path southwest of Kyushu occurs in fall, but never goes beyond 31°N.The northward surface current east of the Ryukyu Islands exists only along Okinawa-Amami Islands from spring to fall.In particular, it appears as an arm of an anticyclonic eddy in fall.