气溶胶光学特性偏振遥感反演算法

Retrieval algorithm for optical parameters of aerosol using polarized remote sensing

陆地上空大气顶的辐射主要由大气散射和地表反射组成,一般地表反射的贡献要大于大气散射的贡献,使得陆地上空气溶胶的特性提取非常困难,而偏振信息只强烈依赖于散射粒子的特性,发展基于偏振信息的气溶胶反演方法是非常有效的.通过对矢量辐射传输方程求解进行研究,基于倍加累加法矢量辐射传输模式分析影响气溶胶反演的主要因素,确定多维参数查找表建立方法,利用POLDER(Polarization and Directionality of the Earth's Reflec-tances)提供的反射率和偏振反射率数据,发展了一种利用反射率和偏振反射率查找表迭代查找反演气溶胶光学参数和地表反射率的算法,实现了对北京、香河、Dalanzadgad观测站上空气溶胶光学厚度、粒子半径、折射指数和地表反射率的反演.用AERONET(Aerosol Robotic Network)地基数据对反演结果进行了验证.

The upwelling radiances at the top of the atmosphere consist of both atmospheric scattering and ground surface reflection. In general, the latter is larger than the former over the land. This makes the extrac- tion of aerosols over land very difficult. It is known that polarization features strongly depend on characteristics of scattering particles. So it is efficient that to retrieve the aerosol characteristics over land area by using this polarization information. Based on the theory of vector radiative transfer algorithms, the relationship of the aerosol＇s properties with parameters in the vector radiative transfer mode was analyzed and the algorithm of look-up table method was confirmed. Using the multi-angle data of polarization and radiance of the polarization and directionality of the earth＇s reflectances（ POLDER）, an algorithm that estimates the aerosol optical properties and surface albedo was developed based on radiance and polarization look-up table with an iterative meth- od. The aerosol optical thickness, efficient radius, refractive index and surface albedo over the Beijing, Xianghe and Dalanzadgad stations were retrieved. The obtained results were validated with the aerosol robotic network （AERONET） measurements.