The Study On Absorption Properties Of Ocean Color Constituents In North Yellow Sea

For the current researches on ocean color remote sensing,people have considerably intensive realization about optical properties in Caseâ… waters,and the inversion models are basically ripe.However,for Caseâ…¡waters,the optical properties of water components are complex and changeable,the comprehensions are still far from enough, and the inversion models are established in experimental and experiential level. Therefore,the optical characteristics of Caseâ…¡waters are the difficulties and emphases in the current international researches on ocean color remote sensing.Based on the in-situ data collected around the North Yellow Sea,including the Dalian Bay and Changhai County,this study has analyzed the ocean color constituents' absorption spectra characteristics,which could help us to understand the optical properties of water in this area and lay the foundation for the establishment on semi-analytic model of ocean color.As one of inherent optical properties,the absorption coefficient of ocean color constituents play an important role in the establishment of inversion model of ocean color remote sensing.So the accuracy of experimental data will directly determine the cognitive level of optical properties of water components and the precision of inversion model.Therefore,laboratory measurements are very important.Firstly,this study introduces the measurement methods of absorption coefficient and some improvements, and then makes comparisons among experimental results from different apparatus or methods.The first research area,Dalian Bay is the typical Caseâ…¡water area,suffering from serious eutrophication.Phytoplankton propagate rapidly,average chlorophyll-a concentration is up to 7.57 mgm^-3 in summer,and red tide disaster frequently occurs, metabolism along with water pollution causes phytoplankton to decline,resulting in an appearance of a great deal of pheophytin,the average concentration could reach 10.9 mgm^-3.Abundant pheophytin change absorption properties of phytoplankton,and bring an important influence on the identification of optical information.Based on the measured data in June 2007,this study mostly focuses on that the impacts of pheophytin on the absorption peak location of the phytoplankton,the relation of chlorophyll a and pheophytin-specific absorption coefficients,the impacts of pheophytin on the absorption peak height of the phytoplankton,and the respective regressed relation of[Pheo],[Chl-a] and[TChl]with the absorption coefficient.In this way,the research will supply an important evidence for identification of the absorption spectrum of phytoplankton and sea water reflectance spectra.The second research area,Changhai County still belongs to Caseâ…¡waters.In this area,the chlorophyll-a concentration is lower than the Dalian Bay;the average value of whole year is only 1.30mgm^-3,but it is worth considering because of the relatively high concentration of de-pigmented particle and yellow substance.The absorption coefficient of phytoplankton nearly correlates with the environmental factors,and appeares significant variations with season.Based on the experimental data in Jan.,Apr.,Jul.and Oct.,this study has analyzed the seasonal relationships.between absorption coefficient and spectral bands,chlorophyll-a concentration and pigment absorption peak,specific absorption coefficients and chlorophyll-a concentration.Thus,these relationships will provide the basis for the establishment of semi-analytical ocean color and primary productivity models.Finally,according to experimental data of de-pigmented particles and yellow substance collected in these two research areas,this study has carried out an in-depth analysis for further understanding,concerning the influence of the ratio of inorganic mineral particles and organic debris particles on the absorption characteristics of de-pigment particles,and the relation of the absorption coefficient a_g(440) and spectral slope S_g of yellow substance.