On the Characteristics of Bottom Tidal Currents in Northeast Taiwan

Abstract

A self-recording current metering subsurface mooring was deployed on the slope where the water depth is 270m, about 14 nautical miles SSE from the Peng-Chia-Yu islet northeast of Taiwan. Data shows that bottom tidal motions are very strong, and their periodicities are diurnal, semidiurnal and fourth diurnal. Semidiurnal tidal motions have the most energy, and act as the major component in the observed current field. Tidal current progressive vector diagram shows that the principal axis of current ellipse points NW-SE. Due to interaction with the sea floor, onshore tidal motions impinging on a sloping continental shelf will acquire a vertical motion which may contribute to the local upwelling.

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