Contribution of secondary condensable organics to new particle formation: A case study in Houston, Texas
Article first published online: 3 AUG 2006
Copyright 2006 by the American Geophysical Union.
Geophysical Research Letters
Volume 33, Issue 15, August 2006
How to Cite
2006), Contribution of secondary condensable organics to new particle formation: A case study in Houston, Texas, Geophys. Res. Lett., 33, L15802, doi:10.1029/2006GL026295., , , and (
- Issue published online: 3 AUG 2006
- Article first published online: 3 AUG 2006
- Manuscript Accepted: 9 JUN 2006
- Manuscript Revised: 10 MAY 2006
- Manuscript Received: 13 MAR 2006
 We report aerosol simulations using the EPA's Models-3 Community Multiscale Air Quality model (CMAQ) and ground-based and aircraft aerosol measurements to investigate new particle formation in Houston, Texas. The aerosol measurements reveal elevated ultrafine particles that reach the highest value in the afternoon, indicating prominent new particle formation. Simulations of the binary H2SO4-H2O nucleation predict an order of magnitude lower concentrations for aerosols near 10 nm than the measurements. A parameterized nucleation scheme that accounts for the enhanced nucleation effect of secondary condensable organics is incorporated into the Models-3/CMAQ. The organic nucleation scheme predicts the number concentrations in agreement with the measurements during the daytime. The diurnal variation is well reproduced in the simulations including the organic nucleation scheme. Comparison with the aircraft measurements also shows that the organic nucleation scheme produces good predictions of the altitude-dependent number size distributions of the ultrafine particles. The results corroborate the importance of secondary condensable organics in new particle formation when sulfate and organics are abundant.