To investigate water exchange between the shallow shelf area and the deep offshore region, we deployed multiple bottom-mounted Acoustic Doppler Current Profilers (ADCPs) from May 2023 to April 2025 along the 150-meter isobath at the shelf break west of Kyushu in the East China Sea. The ADCP data reveal a persistent northward current along the shelf break, exhibiting significant seasonal variation and a pronounced baroclinic structure. During summer, the current intensifies near the surface, while in autumn, a strong current is observed in the subsurface layer. In addition to seasonal fluctuations, the ADCP data indicate oscillations with periods of 10–20 days and 20–40 days, likely corresponding to the passage of frontal eddies. On timescales shorter than two days, the data demonstrate the presence of barotropic and internal tides.
 

the East China Sea shelf