气溶胶形状直接影响散射光强度的空间分布和偏振态，从而改变气溶胶直接辐射强迫。基于球形假设会导致沙尘辐射强迫被严重低估，如何准确获取形状参数是改进以沙尘为主的非球形粒子存在情况下气溶胶直接辐射强迫估算的关键。与强度相比，偏振对形状更加敏感。目前全球气溶胶自动观测网（AERONET）和中国太阳-天空辐射计观测网（SONET）偏振反演的球形度参数仍存在很大不确定性。反演中采用的实验室测得的沙尘形状谱不能反映实际大气状况，是改进反演需首要解决的问题。本项目基于采样和荧光显微测量获取实际大气沙尘形状谱分布，重点研究利用实测的形状谱模型改进形状参数的偏振反演，旨在降低球形度反演的不确定度，同时提高气溶胶光学厚度、单次散射反照率、不对称因子和Angström指数的反演精度，以改进气溶胶直接辐射强迫估算，并系统分析不同沙尘比例下粒子非球形性对辐射强迫的影响。为气溶胶气候效应和全球变化等研究提供重要支持。

Aerosol particle shape directly affects the spatial distribution of intensity and state of polarization of the scattered light, thereby changing the aerosol direct radiative forcing. The radiative forcing of dust aerosols can be severely underestimated based on the assumption of spherical particles. How to accurately obtain the shape parameters is the key to improve the estimation of aerosol direct radiative forcing with the presence of non-spherical particles mainly composed of dusts. Compared with intensity, polarization is more sensitive to particle shape. At present, there are still large uncertainty in the sphericity parameter retrieved from polarimetric measurements within the worldwide AErosol RObotic NETwork (AERONET) and the Chinese Sun/sky-radiometer Observation NETwork (SONET). The fact that dust particle shape distribution based on laboratory measurement cannot reflect the actual status of atmosphere is the most important issue to be dealt with for improving the retrieval. In this project, we plan to obtain the actual atmospheric dust particle shape distribution by sampling and fluorescence microscopy, then focus on improving the retrieval of the shape parameter based on the polarization observations by using the measured shape distribution model. It is aim to reduce the uncertainty of sphericity, and to improve the accuracy of inversions of the aerosol optical thickness, single scattering albedo, asymmetry factor, and the angström exponent simultaneously, then to improve the estimation of aerosol direct radiative forcing. The effects of particle non-sphericity on radiative forcing under different dust proportions will also be systematically analyzed in this project. It will provide significant supports for the researches on aerosol climate effects and global change.