EGU General Assembly 2020
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Influence of size and mixing state on the wet scavenging of black carbon aerosol in the North China Plain

Xihao Pan1, Nan Ma1,2, Yaqing Zhou1, Shaowen Zhu1, Long Peng4, Guo Li2, Yuxuan Zhang2, Jiangchuan Tao1, Xinhui Bi4, Qiang Zhang3, Hang Su2, and Yafang Cheng2
Xihao Pan et al.
  • 1Institute for Environmental and Climate Research, Jinan University, 511443 Guangzhou, China
  • 2Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany
  • 3Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, 100084 Beijing, China
  • 4State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China

Black carbon (BC) is the most important light-absorbing species in the atmosphere and has a strong positive direct radiative forcing. In-cloud scavenging is the major way to wash out BC from the atmosphere. Understanding the connection between its physico-chemical properties and scavenging efficiency is therefore a key to evaluate its lifetime, atmospheric burden and spatial distribution. During an intensive field campaign conducted in the North China Plain in 2019, a ground-based counterflow virtual impactor was utilized to separate fog droplets in radiation fog events. BC mass and mixing state of fog droplet residues were online measured with a single particle soot photometer (SP2). In a strong radiation fog event with visibility of about 50 m, more than 20% fog droplets are found to contain a BC core. BC scavenging efficiency is found to be strongly determined by its diameter and mixing state. Driven by different mechanisms, higher scavenging efficiencies up to 10% are observed for larger and smaller BC particles, and the minimum efficiency is found at BC diameter of 120 nm. For large core (>120 nm) BC-containing particles, the scavenging efficiency increases significantly with coating thickness (CT), from about 10% for CT<100 nm to 80% for CT>300 nm. Chemical composition may also be a key parameter influencing the scavenging of BC. Based on the observation of 3 fog events, parameterizations of BC scavenging efficiency are also given in this study.

How to cite: Pan, X., Ma, N., Zhou, Y., Zhu, S., Peng, L., Li, G., Zhang, Y., Tao, J., Bi, X., Zhang, Q., Su, H., and Cheng, Y.: Influence of size and mixing state on the wet scavenging of black carbon aerosol in the North China Plain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18043,, 2020.