AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Flux Induced Growth of Sub-Kelvin Nano-Particles by Organic Vapor
JIAN WANG, Robert McGraw, Chongai Kuang, Brookhaven National Laboratory
Abstract Number: 258 Working Group: Aerosol Nucleation: From Clusters to Nanoparticles
Abstract New particle formation (NPF) in the atmosphere strongly influences the concentration of atmospheric aerosol, and therefore its impact on climate. New particle formation is a two-stage process consisting of homogeneous nucleation of thermodynamically stable clusters followed by growth of these clusters to a detectable size (> 3 nm). Due to the large coagulation rate of clusters smaller than 3 nm with the pre-existing aerosol population, for new particle formation to take place, these clusters need to grow sufficiently fast before being removed by coagulation. While some previous modeling and field studies have indicated that condensation of low-volatility organic vapor may play an important role in the initial growth of the clusters, it is suggested that due to the small size of the clusters, the strong Kelvin effect may prevent typical ambient organics from condensing on these clusters. Here we show that the particle number flux induced by the heterogeneous nucleation of organics vapor can effectively grow clusters substantially smaller than the Kelvin diameter, traditionally considered as the minimum size of particles that can be grown through condensation. Including this flux can lead to a factor of up to 60 increase in the predicted rates of new particle formation and the subsequent production of cloud condensation nuclei.