基于光学闭合原理的太湖水体颗粒物后向散射特性模拟

后向散射系数是遥感传感器获取水体信息的来源,也是生物光学模型的重要输入参数。利用太湖春季和秋季实测数据,在生物光学模型的基础上结合光学闭合原理模拟了太湖春、秋季节水体颗粒物后向散射系数,进而分析了其光谱特性及颗粒物后向散射概率的时空变化。结果表明,太湖春、秋季节水体颗粒物后向散射系数与总悬浮物、无机悬浮物浓度均具有较高的相关性,而与有机悬浮物浓度的相关性则相对较低,颗粒物后向散射系数随波长变化指数n在太湖春季水体中的变化范围为0.66～1.84,平均值为1.29±0.25,而在太湖秋季水体中的变化范围为0.67～2.40,平均值为1.24±0.34;太湖春季水体颗粒物平均后向散射概率为0.030,而太湖秋季水体颗粒物平均后向散射概率为0.031,且无论是太湖春季水体还是太湖秋季水体,其颗粒物后向散射概率的波长依赖性均较弱。模拟吸收系数与实测吸收系数吻合较好,总体的平均相对误差均在18%以内。

Simulation of Backscattering Properties of Particles in Taihu Lake Based on Optical Closure Principle

Backscattering coefficient is the source of information for remote sensors to acquire water information and it is also an important parameter of bio-optical model. The in-situ data of Taihu Lake in spring and autumn are firstly used to simulate backscattering coefficient based on optical closure principle and its spectral properties and temporal and spatial variation of backscattering rate of particles are analyzed. The results show that backscattering coefficients of particles all have a strong correlation with the concentration of total suspended matters and inorganic suspended matters, but a relatively weak correlation with the concentration of organic suspended matters. The index which changes with wavelength ranges from 0.66 to 1.84 with the mean value of 1.29±0.25 in Taihu Lake in spring and from 0.67 to 2.40 with the mean value of 1.24±0.34 in autumn. Besides, the average backscattering rate of Taihu Lake in spring is 0.030, larger in autumn with a value of 0.031. In addition, the backscattering rates of particles have weak dependence of wavelength in Taihu Lake both in spring and autumn. According to simulation results, absorption coefficients between measured and simulated have good uniformity in Taihu Lake both in spring and autumn and the average relative errors are all little than 18%.