In order to better understand the flow dynamics in the Taiwan Strait (TS) and the adjacent seas, a series of field experiments were conducted to monitor the currents by deploying 30 SVP drifters, using shipboard ADCP measurements and analyzing historical drifter data in the TS. Examinations of historical drifter data reveal that the surface waters in the TS originate from the shelf of the South China Sea (SCS) in the summer. In wintertime, the mean surface current flows toward the south in the northern TS with a mean speed of approximately 0.3~0.4 m/s. The surface current in the eastern TS mainly flows northward, and it flows southward in the western TS in the fall. The surface waters of the Kuroshio do not intrude into the SCS in summer. Instead, a northeastward current of 0.5~0.7 m/s west of Luzon Island impinges on the Kuroshio across the Luzon Strait. Drifter tracks in the TS are classified according to the wind condition. The first type of drifter tracks is that the drifters move northward in the TS with an intensified flows in the Peng-hu Channel when the southwest monsoon prevails. The second and third types of drifter tracks are under the influence of strong northeast monsoon. The drifters are carried onto the shelf of East China Sea from the Kuroshio or the East China Sea, and then move southward along the TS. Some drifters are grounded at the west coast of Taiwan, and the others drift through the TS. The third type of drifter tracks show that drifters start from the Luzon Strait and move northward into the TS. However, they can only reach the neighboring area of Peng-Hu archipelagoes, then they change the direction of drifting to the south or southwest and toward the SCS. The fourth type is that drifters are carried northward from the SCS into the northern TS under the weak northeast wind, and then veer to the south when the northeast monsoon intensifies. The fifth type of drifter tracks demonstrates the flow pattern of the northern TS when the northeast monsoon diminishes. This flow pattern belongs to the Taiwan Warm Current (TWC) in wintertime. The surface speed of TWC is about 0.2~0.4 m/s northward. The second, fourth and fifth flow patterns in the TS have not been quite discovered in previous studies. In-situ marine observations right beneath typhoons are very scanty and valuable. In this study we have found several events with some drifters happened to get caught by typhoons. The maximum speed of drifters near the typhoon center is found to be about 2 m/s. The SST, which is observed by the drifter, reduces 2~4¢J after the typhoon passes. Our results indicate that for the case of the Typhoon Haitang the Matsu weather station measured a sudden increase of wind speed of about 3 m/s every hour, and the corresponding drifter speed increases 0.52 m/s. There were two events in summer of 2006 when the Typhoon Billis and Saomai passed the northern region of Taiwan, and some drifters located at the Kuroshio to the north of typhoon were carried rapidly onto the ECS shelf with a maximum speed of about 1.1 m/s. This result indicates that the Kuroshio waters can penetrate into the ECS shelf by means of the passage of typhoon in this region during summertime. Three cruises with the shipboard ADCP were performed by three research vessels concurrently along two transects during 2002-2004. Various phase averaging methods were employed to eliminate tidal effects. The calculated volume transport of the TS for the period of August 2002, September 2003 and March 2004 is 3.4, 3.6 and 2.8 Sv, respectively. These transport values are compatible with the output of EASCNFS model. The estimated uncertainty of the residual flow through the Peng-hu Channel derived from the 5-phase-averaging, 4-phase-averaging, 3-phase-averaging and 2-phase-averaging methods is 0.3, 0.3, 1.3 and 4.6 cm/s, respectively. Procedures for choosing a best phase average method to remove tidal currents in any particular region are also suggested.

Thesis (M.A.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 55-59).

Thesis (Ph. D.)--Claremont Graduate University, 2007. / Adviser: Jacek Kugler. Includes bibliographical references.

Abstract This study investigates the distributions and controls of transparent exopolymer particles (TEP) in marginal seas around Taiwan. In the euphotic zone of Kuroshio Water off southeast Taiwan, the concentration of TEP generally reached a maximum in the subsurface and then decreased with depth. The maximum concentration of TEP in every station in the Kuroshio Water coincides with the subsurface maximum of chlorophyll a (Chl. a). This implied that TEP in the euphotic zone was controlled by biological rather than physical processes. Furthermore, the ratios of TEP /POC and TEP/DOC increased with Chl. a indicating that the increase of primary production may enhance DOC transformation to POC through the formation of TEP. Concentrations of TEP in the Taiwan Strait and Gaoping coastal sea decreased generally with the increase of seaward distance, showing the same pattern of nutrient distribution. Apparently, the terrestrial input of nutrient may increase phytoplankton abundance and enhance the formation of TEP. Positive correlations were significant between TEP and Chl. a, suggesting that the distribution of TEP in the euphotic zone of Taiwan Strait and Gaoping coastal sea are also controlled by biological processes. During the study period, the concentrations of nutrient and Chl. a were elevated in the surface water around the Dongsha Island in the South China Sea (SCS), due to the influence of internal wave. According to the close relation between TEP and Chl. a, concentrations of TEP around Dongsha Island were also likely controlled by phytoplankton activity, but the different strength of internal wave may lead to the different conditions of TEP, Chl. a and POC distributions. The results of factor analysis support the fact that distributions of TEP are mainly controlled by biological processes, but various physical conditions could also influence distributions of TEP in the water column. Overall, concentrations of TEP are generally higher in the Taiwan Strait and Gaoping coastal sea than in the Donshia shelf sea and Kuroshio Water off southeast Taiwan. Nevertheless, distributions of TEP are all comparable with previous findings in other coastal and marginal seas.

In order to understand tidal circulation and oceanic current for the seas around Taiwan, this study use a baroclinic unstructured grid model to build a high resolution model. This model use semi-implicit method to solve the dynamic of ocean movement and larger time step can be used to calculate. Unstructured grid can be used to resolve complex coastline and variation of depth. TaiDBMv6 depth data were chosen to describe the depth distribution and grid mesh size were determined by local depth, minimum mesh size is about 0.75 minutes, and maximum 13 minutes. Tidal boundaries use 8 constituents derived from FES2004 and calibrated with 34 tide station records. Data of 2009 were used to evaluate the model results. The average of all station root mean square error was 10.1 cm. Station at east side of Taiwan have smaller errors, which almost lower than 5 cm. The maximum error can be found inside Taiwan Strait, about 25cm, mainly caused by lack of depth data near the coastal area. For oceanic current model, GFS and NFS-MC CWB wind forecast were used as meteorology input. Initial fields and boundary condition are derived from HYCOM results. Nudging of salinity and temperature also were used to stabilize the model. Transport of Kuroshio of 2009 is about 17.0¡Ó3.2Sv. Maximum value is about 28.6Sv, occurred in summer. Minimum value is about 8.3Sv, occurred in winter.

This study collected zooplankton and hydrographic data in the Taiwan Strait (TS) using the cruises of ¡§Fishery Research I¡¨ from January 2005 to October 2006, to investigate the seasonal and spatial distribution of planktonic pteropods associated with hydrographic conditions. In total, 29 species of pteropods belonging to 10 genera and 5 families were identified, with mean abundance of 97.14 ¡Ó 66.16 ind./100 m3. The abundances and species number of pteropods exhibited apparent seasonal changes, abundance was higher in summer and lower during winter, while species numbers was higher in fall and lower in winter. Pteropods showed higher diversity in oceanic waters than in shallower shelf waters, but the abundance showed no significant difference. The night-time abundance and species number were significantly higher than the day-time. The effect of typhoon on the abundance and species numbers of pteropods was not significant. The four predominant species found in this study area were Creseis clava, Creseis acicula, Limacina inflate and Limacina trochiformis, together they accounted for 95% of the total pteropod catch, among these, C. clava constitued 48% of the total catch. The pteropod communition was similar among seasons, but ranked differently. Different dominant species showed different seasonal distribution patterns. The distribution of pteropods showed no clear spatial difference in the TS, but higher species richness was usually observed in the southern TS. The pteropods found in this study mostly belonged to the widespread oceanic species, and the dominant species were similar to the previous studies in the South China Sea. The total abundance, species number, and species diversity index of pteropods showed significantly positive correlation with the seawater temperature, and the species number was negative correlated with salinity. Among the four predominant species, the abundance of C. clava, C. acicula, and L. trochiformis were positively correlation with seawater temperature, meanwhile, C. acicula and L. trochiformis showed significantly negative correlations with salinity. This study proposed that the abundance, species number, and species diversity of Pteropods were not obviously influenced by typhoon, instead seasonal succession of water masses and day/night change might be the important factor affecting the distribution patterns of pteropods.

The water masses in the Taiwan Strait (TS) contain the Kuroshio Branch Water (KBW), the South China Sea Surface Water (SCSSW), and the China Coastal Water (CCW). The seasonality of their temporal and spatial variations is modified by the East Asia monsoon and the bottom topography. Hydrographic data acquired during 1985-2003 were studied using a cluster analysis for the classification of the water masses. In addition to the three water masses identified previously, the cluster analysis further classified the Subsurface Water (SBW) under 100 m depth in the Penghu Channel (PHC) and the Coastal Water (CW) along the China coast in summer. Results derived from the cluster analysis together with the T-S diagram suggest that the KBW and SBW dominates in the PHC, whereas CCW occupies in the north TS from January to April. After May, the SCSSW replaces the KBW in the TS through PHC. Meanwhile, the CW distributes along the northwest bank of the TS. After the onset of northeast monsoon in October, the CCW intrudes southward to the northern TS, yet the KBW is confined in the PHC. A zonal oceanic front is clearly seen between the two water masses over the Chang-Yuen Rise in winter. As for the NTMW, it presents below 30 m depth during May and September, and would distribute in depths 0-100 m in other months. The monthly hydrographic databank established in this study has a horizontal grid resolution of 10'x10'. The vertical levels are set at depths 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, and 200 m. The study also concludes that there is hardly a northward flow in the TS in winter connecting the South China Sea Warm Current to the so-called Taiwan Warm Current.

Several cruises of current measurements along various cross-Taiwan Strait transects were conducted by using shipboard Acoustic Doppler Current Profiler (ADCP) during 2001-2003. The main purpose of these experiments is to obtain seasonal variations of flow structures and volume transport in the central and southern regions of the Taiwan Strait. In each cruise the semidiurnal tidal currents were eliminated from the ADCP currents by two different methods, i.e., the phase averaging method and the TSNOW calculation. The subtidal current in the Taiwan Strait generally flows in the parallel-strait direction. In summer when the southwest monsoon prevails, the water in the strait originates from the South China Sea (SCS) or the Kuroshio. This northward-flowing water is divided into two parts by the archipelago of Penghu; the majority keeps flowing northward along the Penghu Channel (PHC), the minority flows northwestward around the Penghu Island. The flows in the surface layer of the PHC reach a maximum speed of 60 cm/s or greater. In winter, strong NE winds push the fresh and cold China Coastal water southward, along the western part of the Taiwan Strait. The SCS or Kuroshio water still flows northward on the eastern part of the strait. The maximum northward current still occurs in the PHC and is around 20 cm/s or less in the winter. Our results from the phase averaging method of all six cruises indicate that the net transports along the Taiwan Strait are all flowing northward, with a maximum value of about 2.5 Sv in summer (August 2001) and a minimum value of about 0.5 Sv in winter (March 2003). The standard deviation of the volume transport is 0.3 Sv. Due to its greater depths and strong currents, the volume transport in the PHC amounts to approximately 75% of the total transport of the Taiwan Strait. Based on the phase averaging results, the transport is related to the along-strait wind by a simple regression: , the sign convention is positive for southwesterly wind and transport.

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Thesis (M.A.)--University of Toledo, 2009. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Arts Degree in Political Science." "A thesis entitled"--at head of title. Bibliography: leaves 76-85.