[A-AS13] New particle formation and its impacts on atmospheric chemistry

[AAS13-P03] The Cloud Condensation Nuclei (CCN) activity during the New Particle Formation (NPF) events in the mountain region of China inland

*Mingfu Cai^1,2, Baoling Liang¹, Qibin Sun¹, Bin Yuan², Min Shao², Haobo Tan³, Lihong Ren⁴, Jun Zhao^1,5 (1.Institue for Environmental and Climate Research, Jinan University, 2.School of Atmospheric Sciences, Sun Yat-sen University, 3.Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, CMA, 4.Atmospheric Chemistry and Aerosol Research Division, Chinese Research Academy of Environmental Science, 5.Southern Laboratory of Ocean Science and Engineering (Guangdong, Zhuhai), Zhuhai)

Keywords:New Particle Formation, Cloud Condensation Nuclei activity, Hygroscopicity

A one-month field measurement was conducted at a mountain site (32°23′ N, 111°02′ E, with an attitude of 862 m) on the Wudang Mountain, Hubei Province, China from 22nd May to 29th June 2018. The particle size number distribution (PNSD, with a size range of 3-400 nm), size-resolved cloud condensation nuclei (CCN, SS=0.2%, 0.4%, 0.6% and 0.8%) and non-refectory PM1 (NR-PM1) chemical composition was measured by a home-made Regular & Nano Scanning Mobility Particle Sizer System (R & N-SMPS), a Cloud Condensation Nuclei Counter (CCNc) and a Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). The new particle formation (NPF) events were observed on 4th, 7th and 11th June during the measurement. These events generally started at around 9:00-10:00 Local Time (LT) with a significant distribution mode of particles with a size range of 3-10 nm. During the events, the wind direction was south west or west and the wind speed was about 3-4 m s-1, which might be favor to the occurrence of NPF event, while the mechanism was unclear. The nucleated particles grew to about 40-50 nm at different time, owing to different growth rate (2.963, 7.573 and 11.383 nm h-1 on 4th, 7th and 11th June, respectively). Probably owing to different atmospheric environment, such as gaseous precursors, oxidant and particle concentration, the formation rate (J3) was different during three events varied from 0.59 to 5.05 cm-3 s-1. The contribution of newly formed particles to the CCN number (NCCN) was mainly depend on their final grown size and the time when they affect the NCCN was decided by the GR. Two types of NPF event enhanced by sulfuric acid or organic vapors was found out during the measurement. Therefore, the hygroscopicity of newly formed particles could varied from a large range (0.25-0.8) and exert a large uncertainty on the NCCN prediction. It found out that the deviation of the NCCN prediction at 0.8% SS could vary from -10% to 38%.