Current distributions in the southern East China Sea in summer

Abstract

Current measurements using a shipboard acoustic Doppler current profiler (ADCP) and two satellite‐tracked buoys, together with conductivity‐temperature‐depth (CTD) casts, were carried out over the continental shelf in the southern East China Sea in July 1995. Two transects for ADCP measurements were defined and divided into segments of ∼56 km. In order to remove diurnal and semidiurnal tidal flows from observed flows, four round‐trip ADCP surveys were conducted along each segment over diurnal tidal periods of ∼24 hours and 50 min. The outflow through the Taiwan Strait, i.e., the Taiwan Current, with velocities of 35–40 cm s−1, was clearly observed to flow northeastward along the coast of China. The volume transport was estimated as at least 1 Sv. The Taiwan Current probably increased width and decreased velocity in the central East China Sea. Bifurcation into two branches of the Taiwan Current shown by previous studies was not observed. Another current entering onto the continental shelf northeast of Taiwan, i.e., the Kuroshio Branch, was found with velocities >15 cm s−1 in the surface, and it helped to make an anticyclonic eddy. The main portion of the Kuroshio Branch flowed northeastward along the 100 m isobath, with a volume transport of ∼0.3 Sv. The Taiwan Current was clearly separated from the Kuroshio Branch by the area of very weak or southward (reverse) flows.