This study investigates the variations of flow field and water mass due to the influence of topographic effect in the Kaoping Submarine Canyon. The data used in this study are collected from five cruises of field observations using research vessel OR3. Instruments deployed include ship-board ADCP¡BCTD¡Btow-ADCP, moored ADCP and vertical arrays of temperature loggers. The collected data are analyzed through a variety of time series analysis technique, such as harmonic analysis¡Blow-pass filter¡BFFT and EOF analysis. The results show that (1) the flow in the Kao-ping Canyon was dominated by semi-diurnal tide. Harmonic analysis shows that both bottom layer and the shelf region are dominated by the M2 tide. The amplitude increases with canyon depth, and the major axis of tidal current align with canyon orientation. (2) Water mass are moving around by the oscillation tidal current along the canyon. During flood, surface water flow to southeast, while bottom flow is up canyon. During ebb, surface water goes to northwest, while bottom flow is down canyon. (3) The low-pass flows indicate a counter-clockwise rotation from surface down, which is explained due to bottom frictional effect. (4) EOF analysis of CTD profiles suggested that the first mode (semi-diurnal tide) can explain 88% of the variations.

In order to better understand the flow dynamics of the Kaoping Submarine Canyon (KSC), this study conducted a series of field experiments to monitor the current, temperature, salinity and tide near the KSC by using shipboard ADCP, CTD and moorings of RCM-8 and workhorse ADCP. Three cruises of Sb-ADCP and CTD have been carried out in September and December of 1999 and May 2000, each lasting two days, while mooring experiment was conducted in June and July, 2000. Least-square fit was applied to the time series Sb-ADCP data of each grid to derive the amplitude and phase of M2 tidal current and the residual flow in the KSC. Our results revealed that a string baroclinic flow field was present in the KSC. Tidal ellipse of the bottom current is dominated by M2 component, with higher M2 percentage in deeper layers. The major axis of the tidal ellipse is parallel to the direction of the canyon axis. In floods, the bottom layer flows down-canyon and the surface layer flows southeastward along the coastline. In ebbs, the situation is reversed. Variations of the temperature and salinity in the bottom layer also exhibit periodic oscillation of the M2 frequency. Daily temperature fluctuation in summer can reach 8 oC, indicating the existence of internal tide in the KSC. The surface residual current flows toward the south east in September and May, with a maximum speed of approximately 30 and 50 cm/s, respectively; the result is probably due to the bifurcation of the summer monsoon flows by the southwestern coastline of Taiwan. In December the surface residual current is northwestward, the maximum speed can reach 80 cm/s. Such a northward mean flow is probably originated from branching of the Kuroshio through Bashi Channel in the winter monsoon season. To summarize, mechanisms for the upwelling event in the KSC consist of surface flow direction, tidal range, and the stratification. The upwelling event occurs more often in the KSC between May and September with the surface mean current flows southeastward or left-bounded. In December when the surface mean current flows northwestward or right-bounded, the upwelling event is rare. An eddy structure of 7 ~ 9 km length scale was observed north of Liu-Chiu Yu, a result possibly produced by Karman vortex street for strong geophysical flows behind an island.

In order to better understand the flow dynamics of the Kaoping Submarine Canyon (KSC), this study conducted a series of field experiments to monitor the current, temperature, salinity and tide near the KSC by using shipboard ADCP, CTD and moorings of RCM-8 and workhorse ADCP. Three cruises of Sb-ADCP and CTD have been carried out in September and December of 1999 and May 2000, each lasting two days, while mooring experiment was conducted in June and July, 2000. Least-square fit was applied to the time series Sb-ADCP data of each grid to derive the amplitude and phase of M2 tidal current and the residual flow in the KSC. Our results revealed that a string baroclinic flow field was present in the KSC. Tidal ellipse of the bottom current is dominated by M2 component, with higher M2 percentage in deeper layers. The major axis of the tidal ellipse is parallel to the direction of the canyon axis. In floods, the bottom layer flows down-canyon and the surface layer flows southeastward along the coastline. In ebbs, the situation is reversed. Variations of the temperature and salinity in the bottom layer also exhibit periodic oscillation of the M2 frequency. Daily temperature fluctuation in summer can reach 8 oC, indicating the existence of internal tide in the KSC. The surface residual current flows toward the south east in September and May, with a maximum speed of approximately 30 and 50 cm/s, respectively; the result is probably due to the bifurcation of the summer monsoon flows by the southwestern coastline of Taiwan. In December the surface residual current is northwestward, the maximum speed can reach 80 cm/s. Such a northward mean flow is probably originated from branching of the Kuroshio through Bashi Channel in the winter monsoon season. To summarize, mechanisms for the upwelling event in the KSC consist of surface flow direction, tidal range, and the stratification. The upwelling event occurs more often in the KSC between May and September with the surface mean current flows southeastward or left-bounded. In December when the surface mean current flows northwestward or right-bounded, the upwelling event is rare. An eddy structure of 7 ~ 9 km length scale was observed north of Liu-Chiu Yu, a result possibly produced by Karman vortex street for strong geophysical flows behind an island.