[Monitoring the total suspended matter of Lake Chaohu based on quasi-analytical algorithm].

There has been some effort by using quasi-analytical algorithm (QAA), which is based on radiative transfer theory to calculate backscattering coefficients of waters. A field investigation in Lake Chaohu was carried out in June, 2009, and a dataset including many parameters such as remote sensing reflectance, absorption and attenuation coefficients, concentration of total suspended matter (c(TSM)), had been obtained. Thereafter, a model for estimating c(TSM), was built, and in order to improve the accuracy, we employed the QAA algorithm to simulate backscattering ratio of Lake Chaohu. The results show that: 1) 807 nm and 834 nm are determined as optimum bands for the Two Near-Infrared Bands Method in Lake Chaohu, and the average specific scattering coefficient of suspended matters at the wavelength of 807 nm and 834 nm is 0.411 m2 x g(-1) and 0.395 m2 x g(-1) respectively; 2) The backscattering ratio of Lake Chaohu is 0.029, and better accuracy is achieved by using this value rather than other empirical values. The root mean square error (RMSE) and mean absolute percentage error (MAPE) of the estimated c(TSM) with calculated backscattering ratio are 12. 143 mg x L(-1) and 24.378%; 3) It is found that stations with high c(TSM) (nearly greater than 30 mg x L(-1)) can have more stable and reliable estimated results.