Search

The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China Sea. Variations in the intensity of Kuroshio Branch and surface currents in the SCS result in seasonal and inter-annual variability in the hydrography of the SE Taiwan Strait, where the northwardly pointing funnel-like Penghu Channel is located. These currents vary with the intensity and direction of monsoons. The teleconnection between air-sea interaction of the east Pacific and west Pacific reportedly has time differences. The data in this study reveal that the salinity of the seawater in the Penghu Channel is highest during El Niño events with a seven-month lag to the monthly Niño 3.4 index, and lowest during La Niña periods, also with a lag of seven months to the monthly Niño 3.4 index. The chemical parameters also vary with these events. The concentrations of apparent oxygen utilization, nutrients, and hydrogen ions vary with the mixing ratio of SCS water and Kuroshio Branch water. The maximum concentrations of nutrients are significantly higher during the summer, seven months after a La Niña event (La Niña-7), than in other seasons. However, biological activities also affected these chemical parameters. In spring, active photosynthesis consumes more nutrients and hydrogen ion concentrations in La Niña-7 periods than in normal-7 periods. [ABSTRACT FROM AUTHOR]

Recent advances in hydrologic optics provide a potential tool for extracting maps of optical properties of optically significant constituents. During summer experiments in the northern South China Sea, a procedure for inverting optical properties in optically complex coastal upwelling waters was performed. We tested an optical inversion model (OIM) that provides estimates of the absorption attributable to optically significant constituents (including phytoplankton, non-algal particles (NAP), colored dissolved organic matter (CDOM)), as well as the chlorophyll a concentration and the phytoplankton size class, from the total spectral absorption. The OIM provided reasonable estimates of these bio-optical products, and attempts to invert the bio-optical properties in the coastal upwelling were successful. Several bio-optical parameters displayed robust relationships to the hydrologic characteristics. The biomass was strongly enhanced in the upwelling, where the phytoplankton population was dominated by the microphytoplankton. The inherent optical properties in the surface waters delivered distinct responses to the coastal upwelling. The distribution of backscattering ratios and particulate size distribution slopes indicated that the offshore surface waters were mainly dominated by small organic NAP, while the upwelling surface water was characterized by larger particles. [ABSTRACT FROM AUTHOR]