Aerosol nonsphericity causes great uncertainty in radiative forcing assessments and climate simulations. Although considerable studies have attempted to quantify this uncertainty, the relationship between aerosol nonsphericity and particle size is usually not considered, thus reducing the accuracy of the results. In this study, a coupled inversion algorithm combining an improved stochastic particle swarm optimization algorithm and angular light scattering is used for the nonparametric estimation of aerosol nonsphericity variation with particle size, and the optimal sample selection method is employed to screen the data. Based on the verification of inversion accuracy, the variation of aerosol aspect ratio with particle size based on the ellipsoidal model in global regions has been obtained from Aerosol Robotic Network (AERONET) data, and the effect of nonsphericity on radiative forcing and dry deposition has been studied. The results show that the aspect ratio increases with particle size in all regions, with the maximum ranging from 1.4 to 1.8 in the desert, reflecting the differences in aerosol composition at different particle sizes. In radiation calculations, considering aerosol nonsphericity makes the aerosol cooling effect weaker and surface radiative fluxes increase, but hardly changes the aerosol absorption, with maximum differences of 9.22% and 22.12% at the bottom and top of the atmosphere, respectively. Meanwhile, the differences in radiative forcing between aspect ratios as a function of particle size and not varying with particle size are not significant, averaging less than 2%. Besides, the aspect ratio not varying with particle size underestimates the deposition velocity of small particles and overestimates that of large particles compared to that as a function of particle size, with maximum differences of 7% and 4%, respectively.

中文翻译：

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大气气溶胶非球形度随粒径变化的模拟与评价研究

气溶胶非球形性给辐射强迫评估和气候模拟带来很大的不确定性。尽管大量研究试图量化这种不确定性，但通常不考虑气溶胶非球形度和粒径之间的关系，从而降低了结果的准确性。本研究采用改进随机粒子群优化算法与角光散射相结合的耦合反演算法对气溶胶非球形度随粒径变化的非参数估计，并采用最优样本选择方法对数据进行筛选。在验证反演精度的基础上，利用气溶胶机器人网络（AERONET）数据，得到了全球区域基于椭球模型的气溶胶长径比随粒径的变化规律，并分析了非球形度对辐射强迫和干沉降的影响。研究过。结果表明，各地区长宽比均随着粒径的增大而增大，在沙漠中长宽比最大值为1.4~1.8，反映了不同粒径下气溶胶成分的差异。在辐射计算中，考虑气溶胶非球形性使得气溶胶冷却效应减弱，表面辐射通量增加，但几乎不改变气溶胶吸收，在大气底部和顶部差异最大，分别为9.22%和22.12%。同时，作为颗粒尺寸函数的纵横比和不随颗粒尺寸变化的纵横比之间的辐射强迫差异并不显着，平均小于2%。此外，与粒径的函数相比，不随粒径变化的纵横比低估了小颗粒的沉积速度，高估了大颗粒的沉积速度，最大差异分别为7%和4%。