卫星PSAC载荷陆地观测中气溶胶和地表参数的信息量分析

Information analysis of aerosol and surface parameters in PSAC observation over land

针对卫星载荷大气校正仪分系统PSAC在陆地上空气溶胶反演领域的应用需求,基于最优化反演框架,引入信息量和后验误差分析方法,讨论了不同观测模式下气溶胶和地表参数的信号自由度(DFS)的观测角度依赖性,给出了气溶胶和地表参数的后验误差。在此基础上,分析了气溶胶和地表参数的DFS随光学厚度(AOD)和地表反射率的变化趋势。研究表明:1)不同的观测几何下,气溶胶参数总的DFS有很大差异,反演气溶胶参数的最优散射角范围是140°~180°;2)任意观测角度,细粒子为主的细模柱浓度v_(0)^(f),粗粒子为主的气溶胶柱浓度v_(0)^(f)和v_(0)^(c)能被反演出来,谱分布部分参数以及折射指数部分参数在大散射角能被反演获得;3)对不同AOD和地表反射率下参数的DFS分析,偏振信息的增加有助于亮地表下气溶胶参数的反演,增加短波红外波段能提升在AOD高值条件下对地表参数的获取能力。

In order to meet the aerosol retrieval application requirements of polarized scanning atmospheric corrector(PSAC)over land,the information content and a posterior error analysis is applied to the synthetic data in this paper,which inherits from the optimal estimate theoretical framework.We discussed the angle dependence of the degrees of freedom for signal(DFS)of the aerosol and surface parameters in different scenarios,and analyzed the posterior errors of the aerosol and surface parameters.On this basis,the variation trend of the aerosol and surface parameters DFS with aerosol optical depth(AOD)and surface reflectivity is analyzed.The results show that:1)Under different observation geometry,the total DFS of aerosol parameters vary greatly,and the optimal scattering angle range of aerosol parameters is 140°~180°.2)The columnar aerosol volumes(v^(f)_(0) and v^(c)_(0))for the coarse mode dominated aerosols and the columnar aerosol volumes(v^(f)_(0))for fine-dominated aerosol models can be inverted at any observation angle,and some parameters of particle size distribution and refractive index can be obtained at large scattering angle.3)The increase in polarization information is helpful to the inversion of aerosol parameters under the bright surface,and the increase of short-wave infrared band can improve the ability to obtain surface parameters under the condition of high AOD.