A Review on Laboratory Studies and Field Measurements of Atmospheric Organic Aerosol Hygroscopicity and Its Parameteriza
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AIR POLLUTION (H ZHANG AND Y SUN, SECTION EDITORS)
A Review on Laboratory Studies and Field Measurements of Atmospheric Organic Aerosol Hygroscopicity and Its Parameterization Based on Oxidation Levels Ye Kuang 1,2
&
Wanyun Xu 3 & Jiangchuan Tao 1,2 & Nan Ma 1,2 & Chunsheng Zhao 4 & Min Shao 1,2
Accepted: 27 September 2020 # Springer Nature Switzerland AG 2020
Abstract Purpose of Review The study of organic aerosol hygroscopic growth and cloud droplet activation is crucial for accurately quantifying their climate and environmental impacts. However, the physical mechanisms behind organic aerosol hygroscopicity variations are not well understood. In this review, we summarized laboratory and field measurements of the organic aerosol hygroscopicity parameter κOA, discussed the physical understanding of why κOA was generally positively correlated with organic aerosol oxidation level, summarized proposed κOA parameterization schemes, and examined possible explanations for the marked differences among these parameterization schemes. Recent Findings Recent findings challenged the general cognition that cloud condensation nuclei (CCN) activity of secondary organic aerosol depended largely on solubility, showing it to be mainly controlled by molecular weight, yet the universality of this finding needs to be further examined. It was found that carbon chain length and functional groups had significant impacts on κOA and additional parameters other than O/C ratio need to be included when parameterizing κOA of multifunctional compounds, which is typically the case for ambient atmospheric aerosols. Additionally, laboratory results of secondary organic aerosol suggest that κOA might be highly RH-dependent under sub-saturated conditions, especially for biogenic secondary organic aerosols. Summary This review summarized laboratory and field measurements of atmospheric organic aerosol hygroscopicity parameter κOA and its parameterization schemes. The results demonstrate that representing κOA with a single oxidation level parameter still bears large uncertainty, and physical mechanisms associated with hygroscopic growth and cloud activation processes of organic aerosol still remain unresolved and need further investigation. Keywords Organic aerosol . Hygroscopicity . Solubility . Hygroscopic growth . Cloud condensation nuclei
Introduction This article is part of the Topical Collection on Air Pollution * Ye Kuang [email protected] 1
Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
2
Guangdong-Hong Kong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
3
State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry, Institute of Atmospheric Composition and Environmental Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China
4
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
Increasing attention has been paid to atmospheric aerosols in recent
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