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China coastal sea is characteristic of the high concentration of suspended matter which has complex components of
mineral particles, organic detritus and phytoplankton, etc. The similarity of spectrum characters of mineral particles and
organic particles in backscattering coefficient, and the organic detritus and color dissolve organic matters (CDOM) in
absorption coefficient makes the information inverse of coastal ocean color become a very difficult work. In this paper,
based on the in situ data of optical investigation in East China Sea in the spring of 2003, including the absorption
coefficients of CDOM and de-pigment particles from laboratory spectrophotometer measurement, and the field
measurement with ac-9 (WET labs, Inc.), the optical properties of suspended particles were studied. And then, a
semi-analysis algorithm of particle attenuation coefficient (Cp) in ECS was developed. There are two key steps in this
algorithm, one is the estimation of the ratio of particle backscattering coefficient to the total scattering coefficient; and
the other is the retrieval of absorption coefficient of CDOM. With this inversion algorithm of Cp and the input of remote
sensing reflectance obtained from the underwater profiler radiometer (Satlantic. Inc.), the particle attenuation coefficient
was inversed, which was consistent well with the in situ data of Cp . In the high turbid water, the scattering signal is
dominant in the Cp values, so the modeled-Cp was less than the in situ data due to the underestimation of backscattering
coefficient in IOPs semi-analysis algorithms. The modeled -Cp at 660nm wavelength has the R2 of 0.84 and RMSE=0.22
compared with the attenuation coefficient at 650nm measured by the ac-9, in which the absorption coefficient of CDOM
is neglect. The semi-analysis algorithms of Cp developed in this paper showed a good potential to estimate the
biogeochemical parameters, like POC, but the further study should be focused on the distinguish of the sub-division
materials with more in situ data set.
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