Aerosol and Clouds
Evaluating the first-order effect of intraannual temperature variability on urban air pollution
Article first published online: 26 JUN 2003
Copyright 2003 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 108, Issue D12, 27 June 2003
How to Cite
2003), Evaluating the first-order effect of intraannual temperature variability on urban air pollution, J. Geophys. Res., 108, 4365, doi:10.1029/2002JD002688, D12., and (
- Issue published online: 26 JUN 2003
- Article first published online: 26 JUN 2003
- Manuscript Accepted: 13 JAN 2003
- Manuscript Revised: 1 OCT 2002
- Manuscript Received: 21 JUN 2002
- Air quality modeling;
- External Mixture
 The direct effect of intraannual temperature variability on ozone and PM2.5 concentrations at the urban scale was simulated using a high-resolution air quality model that tracks the temperature-dependant formation of secondary organic and inorganic aerosol components. Calculations show that the concentration of ozone and non-volatile secondary particulate matter will generally increase at higher temperatures due to increased gas-phase reaction rates. The concentration of semi-volatile reaction products also will increase at higher temperatures, but the amount of this material that partitions to the particle-phase may decrease as equilibrium vapor pressures rise. Calculations performed for Southern California on September 25, 1996 predict that intraannual temperature variability may cause peak ozone and PM2.5 concentrations to fluctuate by up to 16% and 25% respectively. 24-hour average PM2.5 concentrations will decrease with increasing temperatures for inland portions of the South Coast air basin during most of the day. Slight increases in 24-hour average PM2.5 concentrations were predicted for coastal regions. The majority of the predicted shift in PM2.5 concentrations was related to increased production rates for nitric acid and condensable organic compounds balanced against increased volatilization of these products. Semi-volatile particulate ammonium nitrate concentrations are most sensitive to volatilization losses at hotter temperatures and when the ratio of gas-phase ammonia to nitric acid concentrations is approximately unity. Background sulfate particles and particles released from non-catalyst equipped gasoline-powered engines, diesel engines, and food cooking were shifted to smaller sizes as ammonium nitrate volatilized at hotter temperatures.