Diffuse attenuation coefficient of downwelling irradiance at 490nm

Kd（490）

is one of the important ocean optical properties.The retrieval model is of great interest especially for the optically complex water

where terrestrial influence on ocean optical properties is significant.Comprehensive bio-optical dataset were acquired in the nearshore area of the Bohai Sea in 2005.Statistical retrieval model for Kd（490） based on remote sensing reflectance spectra is developed.The model is validated by in situ data with the Absolute Percentage Difference（APD）

Root Mean Square error（RMS

in log10 scale） and Pearson correla-tion coefficient（in log10 scale） of 18.4%

0.094 m-1 and 0.902 respectively between in situ and retrieved Kd（490） values.Error performance of the model is analyzed and it is shown that APD of the retrieval is better than 30% for 76% of all the in situ data.Model’s sensitivity to the input noise is analyzed by imposing ±5% error of remote sensing reflectance spectra artificially

which proves that the model is robust and reliable with the error fluctuation of model output being less than 9% for APD and 0.035 m-1 for RMS.The model is applied to ENVISAT MERIS data to give the spatial distribution of Kd（490） of the Bohai Sea.