1.Nanjing University of Information Science & Technology;2.University of Maryland;3.Beijing Normal University
Taking three aerosol field measurement experiments carried out in 2016 summer at Xingtai (XT) site, 2016 winter and 2017 winter at Beijing (BJ) site as examples, typical new particle formation events during these three experiments are selected to analyze their effects on aerosol hygroscopicity and cloud condensation nuclei (CCN) activity. BJ and XT were considered as two typical cities located in a northern megalopolis area and a central-southern industrial area, respectively, in the North China Plain. The formation mechanism of new particles in different seasons at two sites were different, and the corresponding condensation sink (CS), growth rate (GR), and aerosol chemical composition were also different. The dominant chemical species formed during NPF events was organics at BJ site, but which were sulfate and organics at XT site. The further study found that aerosol hygroscopicity and CCN activity were significantly stronger at XT site than those at BJ site, especially for the nucleation mode particles. The above results indicate that the difference in aerosol hygroscopicity and activation ability should be fully considered when estimating the influence of new particle formation on CCN number concentration.