[Estimating of backscattering rate in Lake Chaohu based on bio-optical model]

Backscattering rate is the important factor of above water spectra. A bio-optical model simplified in near-infrared bands was constructed to estimate backscattering rate in Lake Chaohu by using the in-situ data measured in June 2009. The results show that the maximum value of backscattering rate in Lake Chaohu is 0.059, the minimum value is 0.001 4 and the mean value is 0.023 6. Backscattering rate and spatial differences in the west of Lake Chaohu are all greater than that in the east. In addition, particle refractive index of each sampling site was calculated by using backscattering rate. The dominant factors of in-water particles were determined according to the change scopes of refractive index. The results show that 74% of all sampling sites are dominated by inorganic particles, 18.5% of all sampling sites are dominated by both phytoplankton and inorganic particles, and the rest of sampling sites which accounts only for 7.4% of all sampling sites are dominated by phytoplankton. This indicates that backscattering character of Chaohu Lake is mainly affected by inorganic particles, while the effect of algae particle is relatively small.