鄱阳湖浑浊水体后向散射系数模拟及校正研究

The Simulation and Calibration of Backscattering Coefficient of the Turbid Waters in Poyang Lake

湖泊水体后向散射系数是水色遥感反演模型的重要参数,浑浊2类水体的后向散射特性影响因素较多,相对其他固有光学参数其测量难度大.以鄱阳湖为例,对湖区水体进行野外光学测量,采用半分析模型方法模拟后向散射系数,从而得到本地化的后向散射概率,实现水体后向散射系数的精确校正.研究结果表明:鄱阳湖水体后向散射概率随着波长的变化而改变,呈显著的2次函数关系;鄱阳湖总悬浮颗粒物浓度<50 mg·L-1的中低浑浊水体420、442、470、510、590和700 nm的后向散射概率分别为0. 007 0、0. 012 6、0. 013 9、0. 016 9、0. 023 8、0. 026 9,均值为0. 016 9,标准偏差为0. 008 0;总悬浮颗粒物浓度≥50 mg·L-1的高浑浊水体,在绿光至红光波长的后向散射概率较为稳定,与中低浑浊水体后向散射概率一致;而紫光至蓝光波段不稳定,此段范围是高浑浊和中低浑浊水体的后向散射概率调整的关键波段,420、442 nm的后向散射概率分别调整为0. 006 1和0. 010 2.研究结果可为湖泊浑浊水体后向散射系数精确校正提供研究思路、方法和数据支持.

Backscattering coefficient is an important parameter of water color remotely-sensed retrieval model in lake,there are many factors influencing the backscattering characteristics of caseⅡturbid water,and backscattering coefficient is more difficult measuring than other inherent optical parameters.The optics parameters are measured from Poyang Lake,and the backscattering coefficient is estimated by the semi-analysis model,thus the reasonable backscattering probability is obtained,and the accurate correction of the backscattering coefficient is realized.The results show that the backscattering probability of Poyang Lake changes with the increase of wavelength,and shows a quadratic function of wavelength.The backscattering probabilities of 420,442,470,510,590 and 700 nm respectively are 0.007 0,0.012 6,0.013 9,0.016 9,0.023 8,0.026 9 with low and medium turbid waters in Poyang Lake,and the mean value is 0.016 9,and the standard deviation is 0.008.While total suspended particulate matter concentration in high turbidity waters is greater than 50 mg·L^-1,the backscattering probability of green light to red light band is more stable,which is similar with values from low and medium turbid waters,and the range of purple light to blue light is unstable,so this range is key for the backscatter probability adjustment of turbidity and clear water bodies,the backscattering probabilities of 420 and 442 nm are respectively adjusted to 0.006 1 and 0.010 2 with high turbid waters in Poyang Lake.The research results can provide the support of research ideas,methods and data for accurately calibrating the backscattering coefficient of turbid water bodies in lakes.