Aerosol and Clouds
A criterion for new particle formation in the sulfur-rich Atlanta atmosphere
Article first published online: 4 NOV 2005
Copyright 2005 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 110, Issue D22, 27 November 2005
How to Cite
2005), A criterion for new particle formation in the sulfur-rich Atlanta atmosphere, J. Geophys. Res., 110, D22S02, doi:10.1029/2005JD005901., et al. (
- Issue published online: 4 NOV 2005
- Article first published online: 4 NOV 2005
- Manuscript Accepted: 7 JUN 2005
- Manuscript Revised: 6 MAY 2005
- Manuscript Received: 19 FEB 2005
- new particle formation;
- sulfuric acid
 A simple dimensionless parameter, L, is shown to determine whether or not new particle formation can occur in the atmosphere on a given day. The criterion accounts for the probability that clusters, formed by nucleation, will coagulate with preexisting particles before they grow to a detectable size. Data acquired in an intensive atmospheric measurement campaign in Atlanta, Georgia, during August 2002 (ANARChE) were used to test the validity of this criterion. Measurements included aerosol size distributions down to 3 nm, properties and composition of freshly nucleated particles, and concentrations of gases including ammonia and sulfuric acid. Nucleation and subsequent growth of particles at this site were often dominated by sulfuric acid. New particle formation was observed when L was less than ∼1 but not when L was greater than ∼1. Furthermore, new particle formation was only observed when sulfuric acid concentrations exceeded 5 × 106 cm−3. The data suggest that there was a positive association between concentrations of particles produced by nucleation and ammonia, but this was not shown definitively. Ammonia mixing ratios during this study were mostly in the 1 to 10 ppbv range.