Larger than expected variation range in the real part of the refractive index for ambient aerosols in China

Gang Zhao; Min Hu; Xin Fang; Tianyi Tan; Yao Xiao; Zhuofei Du; Jing Zheng; Dongjie Shang; Zhijun Wu; Song Guo; Chunsheng Zhao

doi:10.1016/j.scitotenv.2021.146443

Larger than expected variation range in the real part of the refractive index for ambient aerosols in China

Sci Total Environ. 2021 Jul 20:779:146443. doi: 10.1016/j.scitotenv.2021.146443. Epub 2021 Mar 14.

Authors

Gang Zhao¹, Min Hu², Xin Fang¹, Tianyi Tan¹, Yao Xiao¹, Zhuofei Du¹, Jing Zheng¹, Dongjie Shang¹, Zhijun Wu¹, Song Guo¹, Chunsheng Zhao³

Affiliations

¹ State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, Ministry of Education (IJRC), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
² State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, Ministry of Education (IJRC), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China. Electronic address: minhu@pku.edu.cn.
³ Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.

PMID: 33752017
DOI: 10.1016/j.scitotenv.2021.146443

Abstract

The real part of the refractive index (RRI) of ambient aerosol, which is widely used in remote sensing and atmospheric models, is one of the key factors determining its particles' optical properties. The characteristics of ambient aerosol RRI in China have not yet been well studied owing to a lack of observations. For the first time, the properties of aerosol RRI were studied based on field measurements in China at four sites with different atmospheres. The results revealed that the measured ambient aerosol RRI varied significantly between 1.36 and 1.78, increasing with the mass ratio of organic components. The scattering coefficient and direct radiative effects of the aerosols were estimated to increase by factors of 2 and 3, respectively, when RRI increased from 1.36 to 1.78. Our results indicate that variation in ambient aerosol RRI should be considered in aerosol and climate models to achieve an accurate estimation of aerosol's radiative impacts.

Keywords: Ambient aerosol; Optical property; Radiative property; Refractive index.