New Particle Formation Events in Urban, Agricultural, and Arctic Environments

Haebum Lee, Hyungjin Cho, Young Jun Yoon, Joonwoo Kim, Bang Yong Lee, KIHONG PARK, Gwangju Institute of Science and Technology

     Abstract Number: 6
     Working Group: Urban Aerosols

Abstract
Atmospheric nanoparticles with diameters ranging from a few to tens of nanometers can be produced by direct emission from various combustion sources and/or indirectly formed by gas-to-particle conversion process. The indirectly-formed particles were resulted from new particle formation (NPF) from precursor molecules through nucleation, condensation, and coagulation processes. The NPF has been frequently observed in various environments, significantly contributes to the number-based aerosol population in the ambient atmosphere. They usually grow to the larger particles, serve as cloud condensation nuclei (CCN) affecting climate change via cloud formation, and contribute to haze formation affecting human health. This study compares NPF characteristics among different atmospheric environments (urban, agricultural (livestock and cropland), and Arctic sites). The NPF occurrence frequency, occurrence criteria, particle formation rate (J), and growth rate (GR) obtained from continuous measurements of number size distribution of particles and various gases were compared to examine any differences in important factors to affect the NPF under different environments. At the livestock site in summer, much higher NH3 (79.6 ppb) and the estimated DMA (52.5 ppt) concentrations than those at other sites led to promote the NPF. At the Arctic, the high level of condensable vapors in addition to H2SO4 under strong photochemical and biological activity and the low level of pre-existing aerosols were maintained in summer, contributing to the higher occurrence of the NPF in summer than other seasons. The J varied more significantly than the GR among different sites, suggesting that the J should be more sensitive to different environments than the GR. Further results on NPF occurrence criteria and controlling factors to the criteria will be presented.