The Analysis of Water Color Constituent Absorption Characteristics in Pearl River Estuary of China

Most of Chinese adjacent seawaters are case 2 waters, while the absorption characteristics of water constituents are quite important parameters on the development of semi-analytic bio-optical algorithms. In this article, based on the in-situ data from the cruise in the Pearl River estuary and sea areas nearby during March to May in 2001, we analyzed the absorption coefficients of the three components (phytoplankton, CDOM and de-pigment particles). Exponential method was chosen to simulate the waveband relations of phytoplankton pigments absorption coefficients a_ph(lambda) by taking 675 nm as the reference wavelength. The empirical model between a_ph(675) and chlorophyll-a concentrations <Chla> was also developed with a good correlation of 0.93. We also calculated the empirical spectral slope value of the CDOM (S_g=0.0170) and that of de-pigment particles absorption coefficients (S_d=0.0116) with the relative standard errors below 10.0%. The verified results, which are tested with the dataset of the same zone at different depth, showed that this spectral model was strongly suitable for this region.