25 Feb 2022
25 Feb 2022
Status: a revised version of this preprint is currently under review for the journal ACP.

Mixing state of refractory black carbon at different atmospheres in China

Gang Zhao1, Tianyi Tan1, Shuya Hu1, Zhuofei Du1, Dongjie Shang1, Zhijun Wu1,2, Song Guo1,2, Jing Zheng1, Wenfei Zhu1, Mengren Li1, Limin Zeng1, and Min Hu1,2 Gang Zhao et al.
  • 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
  • 2Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing, China

Abstract. Black carbon (BC) particles exert a significant influence on the earth's climate system. However, large uncertainties remain when estimating the radiative forcing by BC because the corresponding microphysical properties have not been well addressed. Knowleadge of the BC mixing states of different aging degree can help better characterise the corresponding environmental and climate effects. In this study, the BC size distributions were studied based on three different field campaigns at an urban site, a suburban site, and a background site in China using a single particle soot photometer (SP2) in tandem with a differential mobility diameter. Measurements from the SP2 indicate that the BC particles were composed of either fresh or aged aerosols. The mean number fractions of the fresh BC aerosols were 51 %, 67 %, and 21 % for the urban, suburban, and background sites, respectively. The corresponding mobility diameters of these aged (fresh) BC-containing aerosols were 294 nm (193 nm), 244 nm (161 (nm), and 257 nm (162 nm). The measured aged (fresh) BC core number median diameters were 115 nm (114 nm), 107 nm (95 nm), and 127 nm (111 nm) for urban, suburban, and background sites, respectively. The corresponding aged (fresh) core mass median diameters were 187 nm (154 nm), 182 nm (146 nm), and 238 nm (163 nm) respectively. The mean diameter of the aged BC-containing aerosols was larger than that of the fresh BC-containing aerosols, while the mean BC core diameter of the aged BC-containing aerosols was smaller than that of the fresh BC-containing aerosols. About 10 % of the BC-containing aerosols with the BC core were attached to the other non-BC components, which were mainly generated by coagulation between the BC and non-BC components. The measurement results in our study can help better understand the BC size distributions and mixing status in the different atmospheres in China and can be further used in modeling studies to help constrain the uncertainties of the BC radiative effects.

Gang Zhao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-105', Anonymous Referee #1, 18 Mar 2022
    • AC1: 'Reply on RC1', Min Hu, 23 May 2022
  • RC2: 'Comment on acp-2022-105', Anonymous Referee #2, 14 Apr 2022
    • AC2: 'Reply on RC2', Min Hu, 23 May 2022

Gang Zhao et al.


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Short summary
Black carbon is the second strongest absorbing component in the atmosphere that exerts warming effects on climate. One critical challenge in quantifying the ambient black carbon’s radiative effects is addressing the BC microphysical properties. In this study, the microphysical properties of the aged and fresh BC particles are synthetically analyzed under different atmospheres. The measurement results can be further used in models to help constrain the uncertainties of the BC radiative effects.