Abstract
Determining the standing stock of phytoplankton, inventory of particulate organic carbon and the primary production with remotely sensed ocean color, requires a thorough understanding of the relationship between the chlorophyll a concentration in the surface seawater within one optical depth and other biogenic matter in the euphotic zone. In this study, we investigated the downwelling irradiance of the photosynthetically available radiation (PAR) and chlorophyll a concentration in the sea off northern Taiwan. The log-log plot of the mean attenuation coefficient vs. the average chlorophyll a concentration within the euphotic zone in the sea off northern Taiwan exhibited a linear trend. Consequently, the euphotic zone depth is log-linearly dependent on the average pigment concentration (chlorophyll a + phaeopigment) within the euphotic zone, similar to that observed for the "Case I" water by Morel (1988). Because the Kuroshio water strongly influences upon the shelf waters off northern Taiwan under the prevailing northeast monsoon in spring, it is reasonable to assume that the shelf waters in the southern East China Sea belong to the "Case I" water in terms of bio-optical properties. Under this assumption, the euphotic zone depths in this region were calculated and the inventories of biogenic matter were integrated over the euphotic zone. The inventories of chlorophyll a and pigment concentrations corresponded well with the average concentrations of chlorophyll a and pigment within one optical depth, respectively. A reasonably good correlation was found between the concentration of the particulate organic carbon (POC) and the product of Chl a and PAR. The calculated inventory of POC from such relationship was within ± 15% (1 s.d.) from the measured value.
Published Version
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