Retrieval Of Sea Suspended Sediment Concentration In Offshore Area Base On Remote Sensing Technology

Suspended Sediment Concentration(SSC)is one of the important parameters of seawater,espeacially Case-?water in the offshore,which concentration directly causes a scattering? refraction and absorption to the sunlight in the water,it changes the optical properties of the water,influences the ocean primary productivity indirectly.On the other hand,the movements of the SSC directly or indirectly influence the development of the fishery?Shipping and the exploitation of shelf oil.In recent years,the remote sensing technology of monitering the time-space distribution of the SSC developed quickly,compared with the traditional way of the boat measurements,it's more efficient and timely.Using the speactral datas and the SSC datas of the seawater sample in the study area,based on the analysis of the water spectral characteristics,this paper studys the connection between SSC and the reflectance of the water,builds regression model,and based on the theoretical model,builds SSC retrieval models in Zhoushan offshore area.Finally,it uses the retrieval model to apply to the satellite datas,monitering the time-space distribution of the SSC in Zhoushan offshore area.Main results contents in the paper are the followings:1.The reflectance of the water in Zhoushan offshore area is all less than 0.06sr-1,and it increases with the SSC.The spectral reflection curve changes with the SSC,it has two obvious peaks,the first peak which is much bigger than the second one at the band of 550-600 nm,and the second peak at the band of about 800 nm,when the SSC is low,the second peak is not prominent.The reflectance of the water is insensitve to the SSC at the band of 400-550 nm,when the SSC is reaching a certain value,it changes a little at the band of 600-700 nm and the first peak is not prominent meanwhile.2.Applying the regression model to the satellite datas of the operational land imager(OLI)of LandSat8.The study shows that: OLI4 is most sensitive to the change of the SSC,the band combination of OLI4/OLI2 shows the highest correlation coefficient for the retrieval of the SSC,the quadratic polynomial model of the band combination of OLI4/OLI3 shows the best results,absolute error is 23.18 mg/L,relative error is 55%.3.Applying the regression model to the satellite datas of the HJ-CCD.The study shows that: the band combinations of Re 3 /Re 1 and Re 3 /Re 2 have a great retrieval accuracy,and the band combination of(Re 2 + Re 3)/Re 2 /Re 3 has the best retrieval accuracy,its mean relative error is 19.45%.By using HJ-CCD satellite datas and the models,getting a image of the time-space distribution of the SSC in Zhoushan offshore area,it shows well the characteristics of the seasonal distribution of the SSC in study area.