Atmos. Chem. Phys. Discuss., 7, 6487-6525, 2007
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Sensitivity of PM2.5 to climate in the Eastern U.S.: a modeling case study
J. P. Dawson1, P. J. Adams1, and S. N. Pandis1,2
1Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
2University of Patras, Patra, Greece

Abstract. The effects of various meteorological parameters on PM2.5 concentrations in the Eastern US are examined using the PMCAMx chemical transport model. A suite of perturbations in temperature, wind speed, absolute humidity, mixing height, cloud cover, and precipitation are imposed on base case conditions corresponding to periods in July 2001 and January 2002 in order to determine the sensitivities of PM2.5 concentrations and composition to these meteorological parameters. Temperature had a major effect on average PM2.5 in January (–170 ng m−3 K−1) due largely to the evaporation of ammonium nitrate and organic aerosol at higher temperatures; increases in sulfate production with increased temperature counteracted much of this decrease in July. Changes in mixing height also had major effects on PM2.5 concentrations: 73 ng m−3 (100 m)−1 in January and 210 ng m−3 (100 m)−1 in July. Changes in wind speed (30 to 55 ng m−3 %−1) and absolute humidity (15 to 20 ng m−3 %−1) also had appreciable effects on average PM2.5 concentrations. Precipitation changes had large impacts on parts of the domain (a consequence of the base case meteorology), with sensitivities to changing area of precipitation in July up to 100 ng m−3 %−1. Perturbations in cloud cover had the smallest effects on average PM2.5 concentrations. The changes in PM2.5 concentrations resulting from changing all eight meteorological parameters simultaneously were approximated within 25% or so by summing the changes that resulted when the eight perturbations were imposed separately. The sensitivities of PM2.5 concentrations to changes in these meteorological parameters indicate that changes in climate may have important impacts on PM2.5 concentrations.

Citation: Dawson, J. P., Adams, P. J., and Pandis, S. N.: Sensitivity of PM2.5 to climate in the Eastern U.S.: a modeling case study, Atmos. Chem. Phys. Discuss., 7, 6487-6525, doi:10.5194/acpd-7-6487-2007, 2007.
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