HR: 1330h
AN: A12B-0076    [PDF]
TI: Aerosol Microphysics, Cloud Condensation Nuclei, and Primary Particles: Model Results and Evaluation
AU: * Adams, P J
EM: petera@andrew.cmu.edu
AF: Department of Civil and Environmental Engineering Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 United States
AU: Chen, K
AF: Department of Civil and Environmental Engineering Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 United States
AB: In order to quantify better the indirect effect of aerosols, it is necessary to predict cloud condensation nuclei (CCN) concentrations in general circulation models. Therefore, it is necessary to develop accurate representations of size-resolved microphysics in climate models. Here we will present results from a two-moment sectional model of aerosol microphysics in the GISS GCM II-prime general circulation model. Size-resolved representations of sulfate, sea-salt, elemental and organic carbon aerosols are included. Model results demonstrate that, on a per mass basis, emissions of primary particles are more effective at increasing CCN concentrations than secondary products of gaseous emissions (e.g. sulfur dioxide). Such effects depend on a detailed knowledge of the microphysical processes that produce CCN and, therefore, are not captured by commonly used empirical correlations between CCN and aerosol mass. However, global aerosol models have generally had only modest success in representing well-studied aerosols such as sulfate. Model predictions for more challenging aerosols, such as carbonaceous and mineral dust aerosols, have generally resulted in poor agreement with observations. Therefore, global aerosol models require significant work to improve performance. Evaluation of a size-resolved microphysical model is especially challenging given the lack of observations of aerosol size. As a step towards such an evaluation, preliminary comparisons between size parameters retrieved by MODIS and model results will be shown.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 1610 Atmosphere (0315, 0325)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting