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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-1148
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 Mar 2018
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Method to calculate the aerosol asymmetry factor based on measurements from the humidified nephelometer system
Gang Zhao1, Chunsheng Zhao1, Ye Kuang2, Yuxuan Bian3, Jiangchuan Tao2, Chuanyang Shen1, and Yingli Yu1 1Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
2Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
3State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, 100081, China
Abstract. The aerosol asymmetry factor (g) is one of the most important factors for assessing direct aerosol radiative forcing. So far, few studies have focused on the measurements and parameterization of g. The characteristics of g are studied based on field measurements over the North China Plain by using the Mie scattering theory. The results show that calculated g values can vary over a wide range (between 0.54 and 0.67). When ambient relative humidity (RH) reaches 90 %, g is significantly enhanced by a factor of 1.2 due to aerosol hygroscopic growth. Direct aerosol radiative forcing can be reduced by 40 % when g increases by 20 %. For the first time, a novel method to calculate g based on measurements from the humidified nephelometer system is proposed. This method can constrain the uncertainty of g within 2 % for dry aerosol populations and 4 % for ambient aerosols, taking into account aerosol hygroscopic growth. Sensitivity studies show that ambient RH and aerosol hygroscopicity are the most important factors that influence the accuracy of predicting g.
Citation: Zhao, G., Zhao, C., Kuang, Y., Bian, Y., Tao, J., Shen, C., and Yu, Y.: Method to calculate the aerosol asymmetry factor based on measurements from the humidified nephelometer system, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-1148, in review, 2018.
Gang Zhao et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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RC1: 'Referee's Comments', Anonymous Referee #2, 04 Apr 2018 Printer-friendly Version Supplement 
AC1: 'Reply to RC1', Chunsheng Zhao, 11 May 2018 Printer-friendly Version Supplement 
 
RC2: 'Minor revisions', Anonymous Referee #1, 06 Apr 2018 Printer-friendly Version 
AC2: 'Reply to RC2', Chunsheng Zhao, 11 May 2018 Printer-friendly Version Supplement 
Gang Zhao et al.

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Short summary
The aerosol asymmetry factor (g) is one of the most important factors for assessing direct aerosol radiative forcing (DARF) and remote sensing. So far, few studies have focused on the measurements and parameterization of g. Our studies show that relative humidity has significant impacts on g and DARF due to aerosol hygroscopic growth. For the first time, a novel method based on measurements from the humidified nephelometer system is proposed to calculate g accurately with high time resolution.
The aerosol asymmetry factor (g) is one of the most important factors for assessing direct...
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