New Particle Formation Occurrence in the Urban Atmosphere of Beijing During 2013–2020
Dongjie Shang, Min Hu, Lizi Tang, Xin Fang, Shiyi Chen, Limin Zeng, Song Guo, Yuanhang Zhang, Zhijun Wu
Abstract
Abstract New particle formation (NPF) has strong influences on air quality and global climate. However, it was still ambiguous under which atmospheric condition NPF can occur, due to lack of long‐term observation data analysis. The long‐term measurement of NPF was conducted from 2013 to 2020 at PeKing University Urban Atmosphere Environment MonitoRing Station in Beijing, during which strong pollution control measures were conducted. However, the NPF frequency (NPF‐freq) remained stable within 40.4%–48.9% in an average of 42.5%. The occurrence of NPF events was characterized by lower levels of NOx, condensational sink, relative humidity, and higher levels of wind speed and north wind proportion. SO 2 may act as one limiting factor only in summer. An H 2 SO 4 ‐base nucleation indicator, I 275K was calculated. It was found that I 275K > 243 can separate the NPF and non‐NPF days quite well during the 8 years, with bias at 17%. Accordingly, it was also revealed that the simultaneous control of SO 2 and PM 2.5 (serving as condensation sink) in Beijing happened to cause the stable level of I 275K , as well as the NPF frequency during 2013–2020. The results implicated that along with the reduction of primary emission, the secondary NPF process may become more important in aerosol evolution by its stable frequency, and the precise control of gaseous precursors is required for particle pollution mitigation in the future.