A parameterization of sulfuric acid-dimethylamine nucleation and its application in three-dimensional modeling

Abstract. Sulfuric acid (SA) is a governing gaseous precursor for atmospheric new particle formation (NPF) in diverse environments, which is a major source of global ultrafine particles. In polluted urban atmosphere with high condensation sink (CS), the formation of stable SA-amine clusters, such as SA-DMA clusters, usually initializes intense NPF events. Coagulation scavenging and cluster evaporation are dominant sink processes of SA-amine clusters in urban atmosphere, yet they are not quantitatively included in the present parameterizations of SA-amine nucleation. We herein report a parameterization of SA-DMA nucleation based on cluster dynamic simulations and quantum chemistry calculations, with certain simplifications to largely reduce the computational costs. Compared with previous SA-DMA nucleation parameterizations, this new parameterization would be able to reproduce the dependences of particle formation rates on temperature and CS. We then incorporated it in a three-dimensional chemical transport model to simulate the evolution of particle number size distributions. Simulation results show good consistency with the observations in the occurrence of NPF events and particle number size distributions in wintertime Beijing, showing a significant improvement compared to that using parameterization without coagulation scavenging. Quantitative analysis shows that SA-DMA nucleation contributes majorly to nucleation rates and aerosol population during the 3-D simulations in Beijing (> 99 % and > 60 %, respectively). These results broaden the understanding of NPF in urban atmospheres and stress the necessity of including the effects of coagulation scavenging and cluster stability in simulating SA-DMA nucleation in three-dimensional simulations. This would improve the performance in particle source apportionment and quantification of aerosol effects on air quality, human health, and climate.