光谱响应函数和带宽对光学复杂Ⅱ类水体离水辐射反射率的影响

Effect of Relative Spectral Response and Bandwidth on Water-Leaving Reflectance of Optically Complex CaseⅡWaters

在海洋水色遥感研究中,Ⅱ类水体由于具有复杂的光学属性并受多种物质的共同影响,会使水色遥感数据的应用水平和反演精度降低。从中分辨率成像光谱仪(Moderate Resolution Imaging Spectroradiometer,MODIS)和主题绘图仪(Thematic Mapper,TM)光谱通道的光谱响应函数和带宽的角度出发,分析了其对光学复杂Ⅱ类水体离水辐射反射率的影响。结果表明,MODIS的光谱响应函数和带宽对离水辐射反射率的影响远小于TM相应通道对离水辐射反射率的影响。通过进一步定量分析发现,光谱响应函数和带宽在不同通道和水体下对离水辐射反射率的影响程度不同。针对长江河口三种不同的典型水体类型,利用TM通道的离水辐射反射率模拟了整个通道上的反射率。这样可以更明显地表征出通道内的水体光谱特性,消除光谱响应函数和带宽的影响。

Due to the complex optical properties of case Ⅱ water, the application and inversion accuracy of water color remote sensing data can be reduced in the study of ocean water color remote sensing. The effect of relative spectral response and bandwidth of MODIS and TIM channels on the water-leaving refectance of optically complex case Ⅱ water is analyzed. The analysis result shows that the effect of the relative spectral response and bandwidth of MODIS channels on water-leaving reflectance is much less than that of the corresponding TM channels. In addition, the quantitative analysis result shows that the relative spectral response and the bandwith have their different effect on the water-leaving reflectance of different channels and water types. According to three typical types of water at the mouth of Yangtze River, the water-leaving reflectance of the TM channels is used to simulate the reflectance of the entire channels. Thus, the spectral properties of case Ⅱ water are characterized more obviously and the effect of the spectral response function and bandwidth is removed.