Atmospheric new particle formation in the eastern region of China: An investigation on mechanism and influencing factors at multiple sites

As a major source of cloud condensation nuclei, atmospheric new particle formation (NPF) events exert significant influences on the global climate. Among nucleation mechanisms identified in diverse environments, sulfuric acid-amine nucleation is unique for its high efficiency in forming stable clusters and driving intense nucleation. Despite the fact that this nucleation mechanism can explain observed NPF events at individual sites, its applicability to a larger regional scale remains unclear. Here, we analyze the mechanism and influencing factors of NPF at several sites in the eastern region of China, using measured and theoretically predicted particle formation rates and cluster concentrations. Results show that sulfuric acid and dimethylamine can explain the observed atmospheric nucleation and atmospheric conditions including precursor concentrations and temperature cause the differences in NPF characteristics among sites. This indicates the significance of the sulfuric acid-amine nucleation over a large spatial scale in polluted and populated regions. We also find that oxygenated organic molecules are likely involved in the formation of 1.7 nm new particles at these sites by contributing the initial growth of stable sulfuric acid clusters.