EGU21-13951, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

On the difference of aerosol hygroscopicity between high and low RH environment in the North China Plain

Jingnan Shi1,2, Juan Hong1,2, Nan Ma1,2, Qingwei Luo1,2, Hanbing Xu3, Haobo Tan4,5, Yao He1,2, Qiaoqiao wang1,2, Jiangchuan Tao1,2, Yaqing Zhou1,2, Long Peng1,2, Yafang Cheng6, Hang Su6, and Yele Sun7,8,9
Jingnan Shi et al.
  • 1Institute for Environmental and Climate Research, Jinan University, Guangzhou, Guangdong 511443, China
  • 2Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
  • 3Experimental Teaching Center, Sun Yat-Sen University, Guangzhou 510275, China
  • 4Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, CMA, Guangzhou 510640, China
  • 5Foshan Meteorological Service of Guangdong, Foshan 528010, China
  • 6Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
  • 7State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 8College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • 9Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China

Simultaneous measurements of aerosol hygroscopicity and chemical composition were performed at a suburban site in the North China Plain in winter 2018 using a self-assembled hygroscopic tandem differential mobility analyzer (H-TDMA) and a capture-vaporizer time-of-flight aerosol chemical speciation monitor (CV-ToF-ACSM), respectively. During the experimental period, aerosol particles usually show an external mixture in terms of hygroscopicity, with a less hygroscopic particles mode (LH) and a more hygroscopic mode (MH). The average ensemble mean hygroscopicity parameter (κmean) are 0.16, 0.18, 0.16, and 0.15 for 60, 100, 150, and 200 nm particles, respectively. Two episodes with different RH/T conditions and secondary aerosol formations are distinguished. Higher aerosol hygroscopicity is observed for all measured sizes in the high RH episode (HRH) than in the low RH episode (LRH). In LRH, κ decreases as the particle size increases, which may be explained by the large contribution of non- or less-hygroscopic primary compounds in large particles due to the enhanced domestic heating emissions at low temperature. The number fraction of LH mode at 200 nm even exceeds 50%. Closure analysis is carried out between the HTDMA-measured κ and the ACSM-derived hygroscopicity using different approximations for the hygroscopic parameters of organic compounds (κorg). The results indicate that κorg is less sensitive towards the variation of its oxidation level under HRH conditions but has a stronger O: C-dependency under LRH conditions. The difference in the chemical composition and their corresponding physical properties under different RH/T conditions reflects potentially different formation mechanisms of secondary organic aerosols at those two distinct episodes.

How to cite: Shi, J., Hong, J., Ma, N., Luo, Q., Xu, H., Tan, H., He, Y., wang, Q., Tao, J., Zhou, Y., Peng, L., Cheng, Y., Su, H., and Sun, Y.: On the difference of aerosol hygroscopicity between high and low RH environment in the North China Plain, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13951,, 2021.

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