||In order to understand the influence of topography and geometry to the flow and hydrological environments at Southeast coast of Taiwan, this study analyze data collected by tow-ADCPs in multiple cruises. The results are verified by Argos drifters.|
Field operations of tow-ADCP were carried out on April and September 2009 in the vicinity of Fugang harbor, Taitung. Drifters data were download from the web for the domain 15°N-25°N, 110°E-125°E during January 1st 1986 to July 31st 2010, with a total of 706 drift trajectories.
The results show that: (1) There is a strong northward current near the coast of Taitung with maximum speed of 180 cm/s. The averaged flow velocity is 56 cm/s. The core of the current is centered at 10 km offshore in 200 m water depth. (2) The flow velocity decreases with depth. The average velocity is 97 cm/s in the upper 200 m, 42 cm/s in the middle layer 200m~400 m, and drop to 30 cm/s below 400 m. (3) The flow near the coast is deflected by the bottom topography, with upper layer flow to the northeast along the coastal line. The lower layer flows turn to west and southwest directions. (4) The transport estimated 3.3~7.2 Sv between Taiwan and LuDao (green island). (5) The flows are deflected by the ridge between LuDao and Cheng-Gong. The turns of flow can be explain by the conservation of vorticities, estimated 0.8*10-4s-1~1.2*10-4s-1. (6) The tidal current of is about a half of a knot, shoreward during flood with push Kuroshio northward. The tidal current is offshore during ebb. (7) The drifters data suggest there are eddies in this region. The surface current has seasonality, 80 cm/s in Spring , 100 cm/s in summer, 90 cm/s in fall, and 70 cm/s in winter.