Shang Shao-ling

A dynamic box model of bioactive elements in the southern Taiwan Strait

A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO4−P, NO3−N, AOU, POC and PON in the southern Taiwan Strait region based on the field data of the “Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study” during the period of Dec. 1987–Nov. 1988. According to the unique hydrological and topographical features of the region, six boxes and three layers were considered in the model. The variation rates and fluxes of elements induced by horizontal current, upwelling, by diffusion, sinking of particles and biogeochemical processes were estimated respectively. Results further confirmed that upwellings had important effects in this region. The nearshore upwelling areas had net input fluxes of nutrients brought by upwelling water, also had high depletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen. The abnormal net production of nutrients in the middle layer, (10–30 m) indicated the important role of bacteria in this high production region. The phytoplankton POC contributed about 28% of the total POC. POC settling out from the euphotic zone was estimated to be 2×10−6 g/(m2·s) which was about 35% of the primary production.

Remote sensing of algal blooms using a turbidity-free function for near-infrared and red signals

This article presents a method for real-time mapping of algal blooms in turbid coastal waters using the remote sensing reflectance of red band (Channel 1, 580–680 nm) and near-infrared band (Channel 2, 720–1100 nm) of the AVHRR sensor on the NOAA series satellites. A turbidity-free function for near-infrared and red signals, α0 = (bb(1)/bb(2))(a(2)/a(1)) based on the first order bb/(a+bb) model deducing equation Rrs(2)-1 = α0Rrs(1)-1+g−1 (1-α0), were selected as a chlorophyll-a related index for detecting algal blooms, and the algal blooms with chlorophyll-a concentration of 64–256 mg/L could be defined by window of 1.6 < α0 < 5.2 and 0.01< Rrs(2)/g < 0.2. Such turbidity-free two-band method is supported by both sea-truth data and remote sensing experiment for an algal blooms event on the near-shore water off the Minjiang estuary of southeastern China during early June of 2003. Comparisons of this algorithm with other published algorithms, one-band method (i.e. method of bright water) or two-band methods (i.e. method of ratio, method of NDVI, and method of subtracting) have suggested that the turbidity-free function method could be regarded as a standard algorithm in capabilities of AVHRR imagery or other high resolution but wide near-infrared and red band imagery for detecting algal blooms events in coastal waters.

A vertical distribution model of nutrients and dissolved oxygen in the southern Taiwan Strait

Since vertical transport of nutrients and dissolved oxygen are quite important in the water column and have drawn serious attention these recent years, a one-dimension numerical model is tried to simulate the vertical distribution of nutrients and dissolved oxygen in June at two research sites in the southern Taiwan Strait. Physical transport parameters are calibrated by temperature simulation, and them are used to simulate the profiles of NO3, PO4 and dissolved oxygen. The simulation was generally successful for both stations. The importance of various factors, such as upwelling, tidal current and biogeochemical activities, which influence the vertical distribution of nutrients and dissolved oxygen, is revealed by analysis of the modeling results. Some important rates, fluxes and ratios are also estimated and discussed on the basis of simulation.