Zhang Hong, Huang Jia-Zhu, Li Yun-Mei, Xu Yi-Fan, Liu Zhong-Hua, Xu Xin
Key Laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing 210046, China.
Huan Jing Ke Xue. 2012 Feb;33(2):429-35.
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.
人们已做出一些努力，采用基于辐射传输理论的准分析算法（QAA）来计算水体的后向散射系数。2009年6月在巢湖开展了实地调查，获得了一个包含许多参数的数据集，如遥感反射率、吸收和衰减系数、总悬浮物浓度（c(TSM)）等。此后，建立了一个估算c(TSM)的模型，为提高准确性，我们采用QAA算法来模拟巢湖的后向散射比。结果表明：1）807 nm和834 nm被确定为巢湖双近红外波段法的最佳波段，807 nm和834 nm波长处悬浮物的平均比散射系数分别为0.411 m2·g(-1)和0.395 m2·g(-1)；2）巢湖的后向散射比为0.029，使用该值比其他经验值能获得更高的精度。利用计算得到的后向散射比估算c(TSM)的均方根误差（RMSE）和平均绝对百分比误差（MAPE）分别为12.143 mg·L(-1)和24.378%；3）发现c(TSM)较高（几乎大于30 mg·L(-1)）的站点能得到更稳定可靠的估算结果。
