Remote Sensing Model Of Ocean Colour Parameters In Yangtze Estuary

Ocean color remote sensing is a great significance in monitoring sediment flux and spatial and temporal distribution of suspended sediment in Yangtze estuary. The empirical approach often applies to retrieval of water compositions concentration. However, the disadvantages of empirical algorithms are regional or seasonal effects, fuzzy of information mechanism. In order to accurately retrieve concentration of water compositions, we need understand deep optics properties of ocean color in Yangtze estuary and radiative transfer of light in water, and establish the radiative transfer model and the retrieval model in Yangtze estuary. Based on these reasons, we discuss about inverse problem by in site optics investigation and experimental analysis indoor.Based on the measured data in Yangtze estuary and experimental data indoor, we analyze absorption and scattering properties of water body. Furthermore, the study builds parameterization model about suspended sediment absorption and scattering, chlorophyll absorption, and yellow matter absorption.According to the measured data in Yangtze estuary, the characters of reflectance spectrum were analyzed. There are eight types reflectance spectrum. We put forward an algorithm of spectrum slope in order to distinguish different spectrum types. The algorithms applied to water body classification of MODIS images. The results are consistent with the facts and monitor dynamic distributions of different water body.The study builds water radiative transfer model by using previous research results for reference, and model remote sensing reflectance on water surface. The result shows the radiative transfer model and parameterization model is effective in the range of low-middle concentration of suspended sediment. However, in the range of high concentration (>0.2km/m3), the result is inconsistent with fact. The model indicates the depth of euphotic zone is less than water depth in the different type water body. This show the water-leaving radiances on water surface mainly come from radiance contribution of water body itself, and bottom effects are negligible. Based on the depth of euphotic zone, the paper suggested the optically weighted suspended sediment concentration instead of surface concentration when building traditional empirical algorithms in order to reflect truly suspended sediment concentration correspondence with remote sensing reflectance.Coupling non-linear optimization techniques and water body radiative transfer, the article set up ocean color retrieval model. The retrieval results show the average error of suspended sediment is 25.3%, and the average error of chlorophyll concentration is 31.5%, and the average error of yellow matters absorption is 59.4%. The retrieval precision of suspended sediment concentration and chlorophyll concentration is high. However, the retrieval precision of yellow matter absorption is low.