On the shelf break in northeast of Taiwan, a buoy-mounted, upward looking Acoustic Doppler Current Profiler (ADCP) was modered at 270 m to record the current velocity above it. The obtained data was used to study the vertical structure of the semi-diurnal tidal current and its temporal variations. The deployment duration was from September 28 to November 27, 1991 for 59 days. Both barotropic and first baroclinic semi-diurnal tides were found to be important in this area. The nodal point of the first baroclinic tide was located at 110m -130m. The Kuroshio intrusion, which occurred in mid-October, had a relatively small impact on the barotropic tide but a large one on the baroclinic tide. The speed of the barotropic and baroclinic tides were comparable before the intrusion, but subsequent to the intruded, the baroclinic tide accelerated, and its tidal ellipses showed considerable change in its orientation and exxentricity. In contrast, the difference in barotropic tidal ellipses before and after the intrusion were small.

Changes in local water stratification and background low-frequency current induced by the intrusion of the Kuroshio ma)1 have been responsible for the observed variations in the vertical structure of the semi-diurnal tide.