Research on The Surface Reflectance Model in Satellite Measurement Scale

在这项研究中，我们利用Terra MODIS图像和地面测量的气溶胶光学厚度(AOT)，确定了日本陆地地区可见光和红外波段的表面反射率比。对于陆地的BRDF模型，我们使用法国Medias Postel的POLDER-1推导的BRDF数据库，分析了以前提出的经验BRDF模型，如Li_Sparse-Ross_Thick模型和Li_Sparse-Ross_Thick带热点模型。这些模型由三个核成分组成，即各向同性核成分、几何核成分和体散射核成分。我们确认，通过选择适当的系数，它们能够符合大多数目标类别的测量BRDF值。由于我们发现阴影函数是体积散射核分量的一个很好的候选者，它应该更倾向于使用，而不是经验分量，因为我们可以根据辐射传递理论从理论上推导出阴影函数。针对陆地目标，提出了基于Li稀疏阴影的BRDF模型，并对不同的BRDF目标进行了测试；对于海面BRDF，基于对太阳闪耀光斑图像的分析，在Cox-Munk模型中提出了新的风速和表面斜率参数。

In this study, we determined the surface reflectance ratios between visible and infrared bands for land areas in Japan, using Terra MODIS images and the ground-measured aerosol optical thickness(AOT). We obtained a satisfactory agreement between the satellite-retrieved and ground-retrieved AOT, using the newly determined reflectance ratios.As for the BRDF models for lands, we analyzed the previously proposed empirical BRDF models, such as the Li_sparse-Ross_thick model and Li_sparse-Ross_thick with Hot Spot model, using the BRDF Database derived from POLDER-1 by POSTEL, Medias France. These models consist of three kernet components, namely, an isotropic, a geometric and a volume scattering kernel components. We confirmed they are able to fit the measured BRDF values for most target categories, by choosing appropriate coefficients. Since we found the shadowing function is a very good candidate for a volume scattering kernel component, it should prefer to use, instead of empirical component, because we can derive the shadowing function theoretically, based on the radiative transfer theory. We proposed the Li-sparse-shadowing BRDF model for land target and the proposed model was tested successfully for various measured BRDF targets.As for the sea surface BRDF, we proposed new parameters for the wind speed and surface slope in the Cox-Munk model, based on the analysis of the sun glitter POLDER images.