利用A-Train卫星联合反演研究中国地区气溶胶直接辐射强迫的时空变化

关于气溶胶直接辐射强迫估计仍存在较大的不确定性。一个重要因素是对影响辐射强迫的气溶胶单次散射反照率、不对称参数，以及气溶胶垂直廓线缺乏足够的了解。当前的被动遥感卫星均不能反演单次散射反照率与不对称参数，而地基反演的空间覆盖率非常有限，难以满足大尺度研究的需求。本项目拟使用NASA A-Train系列卫星的多个传感器联合反演气溶胶的单次散射反照率与不对称参数。我们将利用AERONET以及SONET地面观测建立气溶胶模型并生成反演查算表，使用MODIS光学厚度，OMI吸收光学厚度，PARASOL细粒子光学厚度，CERES大气层顶太阳辐射作为约束条件，通过查表与最优化的方式进行反演，再结合CALIPSO星载激光雷达观测的气溶胶垂直廓线以及GISS辐射传输模式，更好地估计中国地区气溶胶的直接辐射强迫，并分析中国地区气溶胶辐射强迫的时空分布和季节变化特征。

Large uncertainties still remain in the estimation of aerosol climate forcing. One of the important reason is the lack of sufficient knowledge of aerosol single scattering albedo, asymmetry factor and vertical profile, while these three factors significantly impact on the direct aerosol forcing. None of the current passive satellite sensors is capable of retrieving aerosol single scattering albedo and asymmetry parameter. Although they can be obtained by ground observation, the spatial coverage is too limited for large-scale studies. We propose to jointly retrieve these two aerosol parameters using multi-sensor observations from the NASA A-Train constellation. Specially, we will first construct aerosol models using AERONET and SONET ground observation, and calculate look up tables using radiative transfer model with different aerosol model combinations. Then using MODIS optical depth, OMI absorption optical depth, PARASOL fine mode optical depth and CERES TOA shortwave radiation as constraints, we can find the single scattering albedo and asymmetry parameter that best matches observation through optimization techniques. We will combine these parameters with CALIPSO retrieved aerosol vertical profile and use GISS offline GCM to calculate aerosol direct radiative effects. We will further analyze the spatial-temporal variability of aerosol direct forcing in China.