卫星探测信号包含大气中分子和粒子的散射贡献以及地表反射的贡献,在陆地上空二者的贡献相当,并且陆地地表反射率在时间和空间上极度不均一,因此,很难区分二者的各自贡献从而定量提取大气气溶胶和地表反射率,陆地上空气溶胶的反演也一直是一个极具挑战性的课题.而高分辨率卫星资料如TM5的可见光通道能够很好地区分云和云下阴影,如果云是不透光的,在阴影上空,卫星信号仅包含大气散射贡献和地表漫反射贡献,而在邻近的非阴影区上空,卫星探测信号还包含地表直接反射的贡献,根据这个原理,利用辐射传输模式分析了阴影区和非阴影区上空卫星探测的辐射量差别与地表反射率和大气气溶胶的关系,提出一种利用云下阴影来同时提取阴影上空大气气溶胶和地表反射率的单波长反演方案,并对气溶胶单次散射反照率,散射相函数,测量精度以及地表反射率的不均一性进行了敏感性分析.

The satellite measurements in the visible and near Infrared band are the contribution of surface reflectance and atmospheric back scattering, and it is very difficult to distinguish one form the other for both contribution have the same order over land. The images from high spatial resolution orbit sensor such as TM5 flying on LANDSAT are very clear to discriminate cloud and the shadow since they are projected on the surface from cloud free pixels in the visible hand. Over a nontransparent cloud shadow, the radiance obtained from satellite measurement is the contribution of atmospheric path radiance and surface diffuse reflection; while, over a bright area surrounding the cloud shadow, besides the contribution of atmospheric radiance and surface diffuse reflection, the surface direct reflection also contributes to the radiance measured from satellite. Based on this theory, the difference between the two radiances and its relationship with the surface reflectance and aerosol optical thickness are analyzed, and a new method to retrieve surface reflectance and serosol optical thickness simultaneously over land is developed. At the end of this paper, sensitivity analysis of measurement, single scattering albedo and aerosol scattering phase function to the retrieval of surface reflectance and aerosol optical thickness are given.