17 Jun 2022
17 Jun 2022
Status: this preprint is currently under review for the journal ACP.

Measurement report: Size distributions of urban aerosols down to 1 nm from long-term measurements

Chenjuan Deng1, Yiran Li1, Chao Yan2,3,4, Jin Wu1, Runlong Cai2, Dongbin Wang1, Yongchun Liu3, Juha Kangasluoma2,3,5, Veli-Matti Kerminen2, Markku Kulmala2,3,4, and Jingkun Jiang1 Chenjuan Deng et al.
  • 1State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 100084 Beijing
  • 2Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
  • 3Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 100029 Beijing, China
  • 4Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
  • 5Karsa Ltd., A. I. Virtasen aukio 1, 00560 Helsinki, Finland

Abstract. The size distributions of urban atmospheric aerosols convey important information on their origins and impacts. Their long-term characteristics, especially for sub-3 nm particles, are still limited. In this study, we examined the characteristics of atmospheric aerosol size distributions down to 1 nm based on four-year measurements in urban Beijing. Using cluster analysis, three typical types of number size distributions were identified, i.e., daytime new particle formation (NPF) type, daytime non-NPF type, and nighttime type. Combining a power law distribution and multiple lognormal distributions can well represent the sharp concentration decrease of sub-3 nm particles with increasing size and the modal characteristics for those above 3 nm in the submicron size range. The daytime NPF type exhibits high concentrations of sub-3 nm aerosols together with other three modes. However, both the daytime non-NPF type and the nighttime type have a low abundance of sub-3 nm aerosol particles together with only two distinct modes. In urban Beijing, the concentration of H2SO4 monomer during the daytime with NPF is similar to that during the daytime without NPF, while significantly higher than that during the nighttime. The concentration of atmospheric sub-3 nm particles on NPF days has a strong seasonality while their seasonality on non-NPF days is less pronounced. In addition to NPF as the most important source, we show that vehicles can emit sub-3 nm particles as well, although their influence on the measured aerosol population strongly depends on the distance from the road.

Chenjuan Deng et al.

Status: open (until 29 Jul 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Chenjuan Deng et al.

Data sets

Datasets to: Measurement report: Size distributions of urban aerosols down to 1 nm from long term measurements Deng, Chenjuan, Yan, Chao, Li, Yiran, Wu, Jin, Cai, Runlong, Wang, Dongbin, Liu, Yongchun, Kangasluoma, Juha, Kerminen, Veli-Matti, Kulmala, Markku, & Jiang, Jingkun

Chenjuan Deng et al.


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Short summary
The size distributions of urban atmospheric particles convey important information on their origins and impacts. This study investigates the characteristics of typical particle size distributions together with key gaseous precursors from the long-term perspective in urban Beijing. A fitting function is proposed to represent and help to interpret the size distribution including particles and gaseous precursors. In addition to NPF as the major source, vehicles can emit sub-3 nm particles as well.