Simulation and evaluation study of atmospheric aerosol nonsphericity as a function of particle size--颗粒学报PARTICUOLOGY

Mao, Q., & Nie, X. (2024). Simulation and evaluation study of atmospheric aerosol nonsphericity as a function of particle size. Particuology, 90, 281-291. https://doi.org/10.1016/j.partic.2023.12.013

Simulation and evaluation study of atmospheric aerosol nonsphericity as a function of particle size

Qianjun Mao ^a, Xin Nie ^b *

a School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, China
b College of New Energy and Materials, Northeast Petroleum University, Daqing, 163318, China

10.1016/j.partic.2023.12.013

Volume 90, July 2024, Pages 281-291

Received 8 July 2023, Revised 11 December 2023, Accepted 19 December 2023, Available online 3 January 2024, Version of Record 1 February 2024.

E-mail: niexin202302@163.com

Highlights

• A nonparametric estimation procedure for aerosol nonsphericity has been written.

• Variation of aerosol nonsphericity with particle size in global regions is inverted.

• The radiation and dry deposition effects of aerosol nonsphericity have been evaluated.

Abstract

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.

Graphical abstract

Keywords

Aerosol nonsphericity; Inversion; Aspect ratio; Radiative forcing; Dry deposition velocity

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