Optical Properties Of Chlorophyll And Remote Sensing Application In Yangtze Estuary And Adjacent Sea

The optical properties of phytoplankton in Yangtze estuary and adjacent seais a great significance in monitoring the water quality, primary productivity and carbon cycle. It has a comprehensive understanding by studying chlorophyll-a concentration, methods of determination of particulate absorption coefficient and optical properties of water components. Based on these studies, the chlorophyll-a concentration inversion model was discussedComparing the transmission method and transmission-reflection method, it was found that NaCIO solution which has 0.1% active Cl- had a good effect in extraction the pigment. And wash the sample after fade process can reduce the error caused by NaClO. For the high-turbidity water, transmission method is not recommended. It was suggested that use the transmission-reflection method in the west of the plume-peakwhere the sediment concentration was above 80mg/l and use both the transmission method and transmission-reflection method in the east of the plume-peak where the water is clean(sediment concentration<20mg/l).The chlorophyll-a concentration which changed little in the spring, summer and autumn inside the mouth of Yangtze River appears a high value between 122.5°E and 123°E in 2009. This high value area will appear offset with the changing of the runoff of Yangtze River. The chlorophyll-a concentration showed a "small-large-small"distribution in Yangtze estuary. The high chlorophyll-a concentration located in Zhoushan Islands in the four water layers which is characterized by concentration: surface> 5m>10m>15m in summer. And in autumn,this phenomenon is less obvious. In addition to the surface, the concentration of chlorophyll-a in the other three water layers increased from west to east.Yangtze estuary shows complex optical properties, the reflectance spectra presents four shapes with the change of the concentrations of water components. Because of the different ratio of the concentrations of phytoplankton and sediment,the absorption spectra of total particulate is characterized by phytoplankton or non-algae particle(NAP). Based on the parameters of chlorophyll absorption coefficient, we can simulate the absorption spectra with the root mean square error 0.046. The Colored Dissolved Organic Materials(CDOM) and non-algae particle exponential decay with wavelength, the CDOM spectral slope distribution in the 0.011～0.016nm-1 and the NAP is 0.005～0.011nm-1.The distribution of CDOM in the Yangtze estuary was decrease from the mouth to the southeast.The accuracy of semi-analytical model in Yangtze estuary was low and the root mean square enrror was up to 10mg/m3 because of the impact of high scattering, complex of color components and too many experience parameters which were difficult to determine. By the two-band, three-band and Synthetic Chlorophyll Index(SCI) model, the empirical models for application in Yangtze estuary were discussed. Two-band ratio method, three-band ratio method and SCI model were used to retrieval of chlorophyll-a concentration in the summer of 2009 in Yangtze esutry. The results showed that the accuracy of SCI model was better than two-band and three-band algorithm, and both in clear or turbid water,the SCI model has a good effect on inverse.