[Estimating of suspended matter concentration based on bio-optical model in Chaohu Lake]

Remote sensing reflectivity (R(rs)), total suspended matter (TSM), absorption and scattering properties of 32 sampling sites in situ were measured in June 2009. The inherent optical properties (IOPs), such as absorption and scattering properties of different components in Chaohu Lake, were analyzed according to these data. And specific scattering coefficient of suspended matters and the backscattering ratio which were the indispensable inherent optical parameters were identified. Then an inversion model based on bio-optical model was constructed and quasi-synchronous HJ-1 CCD images were used to inverse the concentration of suspended matters in Chaohu Lake. Results showed that, the average specific scattering coefficient of suspended matters at the wavelength of 555 nm was 0.48 m2/g. A power model about specific scattering coefficient of suspended matters was constructed by choosing 555 nm as a reference wave band with determination coefficient of 0.99. In addition, the backscattering ratio didn't rely on the wavelength from 700 nm to 900 nm (Band 4), and its value is stable at 0.051. A remote sensing reflectivity model was constructed by IOPs and apparent optical properties (AOPs) to obtain TSM in Chaohu Lake. The trend of relative error between measured values and inversed values decreased with the concentration of TSM increasing. And the average relative error value was 17.25% by using this model. This showed that this method was applicable to inverse TSM in inland lake with high concentration suspended matters. Based on two CCD image data of HJ-1 satellite, the inversion of suspended matter concentration mainly changed between 0 and 100 mg/L in Chaohu Lake. The suspended matter concentration higher than 40 mg/L covered 54.37% area of Chaohu Lake in June 13 and that of 61.62% in June 15. As well as, the distribution of suspended matter concentration inversed by using two HJ-1 CCD images of Chaohu Lake kept correspondence with climate changes at that time.