Two bottom-mounted ADCPs were deployed in the coastal waters off the National Museum of Marine Biology and Aquarium at southwestern Taiwan coast from June 5, 2004 to December 20, 2005. The long-term observational dataset of wind, currents, water level and drifters were analyzed here to investigate the mechanism and seasonal variations of tidal and subtidal flows.
Diurnal tidal constituent of K dominates the tidal energy in this area. The calculated form ratio is 1.53, indicating that the tide is of the diurnal type. Tidal current direction is consistent with the local coastal line, with the principal axis in the NNE-SSW orientation. The tidal waves of two major constituents¡]K an M ¡^are found to exist in the form of propagating waves in this region, rather than the form of standing waves as was found in the east coast of central Taiwan Strait.
The subtidal currents flow toward the south with a speed of about 20-50 cm/s during the winter northeastern monsoon. On the other hand, subtidal flow speed is smaller but still toward the south during the summer southwestern monsoon. Current speed in the surface layer is larger than that in the mid and bottom layers. The persistent southward flow in this region is also found to correlate with the wind stress curl. When the wind stress curl reaches a maximum negative value in winter, an anticyclonic eddy develops and the flow in the study area is toward the south. Analysis of Argos drifter data reveal the existence of anticyclone off the southwestern Taiwan coast.
Surface drifters were also deployed in this area, and the trajectories indicate that general flow patterns are toward the south. This finding is consistent with the progressive vector diagram from the moored ADCP current data.
To summarize, a persistent southward flow exists in the study region all year round. However, the flow intensifies in winter and decays in summer. The southward flow is also associated with the anticyclonic eddy driven by the negative wind stress curl in winter. The intrusion of Kuroshio water from the Luzon Strait into the northern South China Sea is the possible source of water mass for this phenomenon.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0913106-101752 |
| Date | 13 September 2006 |
| Creators | Yang, Wan-hua |
| Contributors | Ruo-Shan Tseng, Yu-Huai Wang, Li-Guang Leu, Shiou-Wen Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0913106-101752 |
| Rights | campus_withheld, Copyright information available at source archive |
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