Source water of two-pronged northward flow in the southern Taiwan Strait in summer

Journal of Oceanography (Impact Factor: 1.27). 07/2011; 67(4):385-393. DOI: 10.1007/s10872-011-0036-1


It is generally accepted that the flow is northward in the Taiwan Strait during summer and that the strongest current is detected in the Penghu Channel between the Penghu Islands and the Taiwan Island. This current, the eastern prong flow, is made up of waters from the South China Sea (SCS) and the Kuroshio. North of the Penghu Islands, the current veers to the west before turning northward again because of the shallow Chang-Yuen Ridge, and extends westward off the coast of Taiwan. There is a second prong of northward flow existing between the Taiwan Bank and the China mainland coast. Here, we show with observational data as well as results from a numerical model that this water receives little influence from the Kuroshio and is distinctively cooler, fresher, less oxygenated and more acidic, and contains more dissolved inorganic carbon than waters at the same density level of the eastern prong. Evidence is provided to show that the source water of the western prong should be the subsurface water from the strong upslope advection flowing northward from the SCS to the southern Taiwan Strait and upwelling along the coast during the favorable southwesterly wind. Subsequently, the upwelled water flows over the saddle west of the Taiwan Bank and joins the main flow northwest of the Penghu Islands.

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Available from: Chen-Tung Arthur Chen,
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    • "This was perhaps the reason why the concentrations of some studied metals in the sediments from some inshore and/or estuarial sites were lower than those in the sediments from some offshore sites (Fig. 2). Site 5 had the lowest metal concentrations perhaps mainly because the waters there are from the Kuroshio branch (Chen and Wang 2006; Hong et al. 2011; Qiu et al. 2011), which is of "
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    ABSTRACT: The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd > Pb > Ni > Zn > Cu > Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd > Pb > Ni > Cu > Zn > Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.
    Environmental Science and Pollution Research 10/2015; DOI:10.1007/s11356-015-5669-y · 2.83 Impact Factor
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    • "There are four papers related to the current, upwelling, or water mass in the Taiwan Strait and in the Beibu Gulf. Hong et al. (2011) analyze the observational data and numerical model results and confirm the two-pronged northward flow in the southern Taiwan Strait in summer. Qiu et al. (2011) "
    Journal of Oceanography 12/2011; 67(4):359-363. DOI:10.1007/s10872-011-0063-y · 1.27 Impact Factor
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    ABSTRACT: In order to understand the fate of nutrients in the Taiwan Strait during summer, we built a coupled physical-biological numerical ocean model, which can capture the basic hydrographic and biological features within the strait. The nutrient that we chose to model is dissolved inorganic nitrogen (DIN). The model includes individual reservoirs for nitrate (NO3) and ammonium (NH4). Both the observational evidence and model results show that NO3 in the strait originates primarily from the upwelling subsurface water in the northern South China Sea (SCS) that enters the strait via the eastern and western routes separated by the Taiwan Bank. The coupled physical and biological effects on the NO3 transport at these two routes are highlighted in the study. For the western route, the shallow topography and the coastal upwelling intensify the biological uptake of NO3 in the whole water column. Consequently, the nitrogenous contribution by this route is mainly in form of the particulate organic nitrogen (PON). In contrast, NO3 is transported conservatively below the nitricline at the deep eastern route, contributing the whole NO3 supply in the TWS. The model estimates the fluxes of DIN and PON into the TWS, from the northern SCS, are 1.8 and 4 kmol s-1, respectively. Over half (˜1 kmol s-1) of the DIN is synthesized into PON by the phytoplankton in the strait. Overall, this study estimates the physical and biological effects on the nutrient transport in the TWS during summer.
    09/2013; 118(9):n/a-n/a. DOI:10.1002/jgrc.20300
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