Atmos. Chem. Phys. Discuss., 9, 19471-19507, 2009
www.atmos-chem-phys-discuss.net/9/19471/2009/
doi:10.5194/acpd-9-19471-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Evaluation of aerosol distributions in the GISS-TOMAS global aerosol microphysics model with remote sensing observations
Y. H. Lee1 and P. J. Adams1,2
1Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
2Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA, USA

Abstract. The Aerosol Optical Depth (AOD) and Angstrom Coefficient (AC) predictions in the GISS-TOMAS model of global aerosol microphysics are evaluated against remote sensing data from MODIS, MISR, and AERONET. The model AOD agrees well (within a factor of two) over polluted continental (or high sulfate), dusty, and moderate sea-salt regions but less well over the equatorial, high sea-salt, and biomass burning regions. Underprediction of sea-salt in the equatorial region is likely due to GCM meteorology (low wind speeds and high precipitation). For the Southern Ocean, overprediction of AOD is very likely due to high sea-salt emissions and perhaps aerosol water uptake in the model. However, uncertainties in cloud screening in high latitude make it difficult to evaluate the model AOD at high latitudes with the satellite-based AOD. AOD in biomass burning regions is underpredicted, a problem also seen in other global aerosol models but more severely in this work. Using measurements from the LBA-SMOCC 2002 campaign, the surface-level OC and EC concentrations in the model are found to be underpredicted severely during the dry season, suggesting the low AOD in the model is due to underpredictions in OM and EC mass. These, in turn, result from unrealistically short wet deposition lifetimes during the dry season in the GCM.

Citation: Lee, Y. H. and Adams, P. J.: Evaluation of aerosol distributions in the GISS-TOMAS global aerosol microphysics model with remote sensing observations, Atmos. Chem. Phys. Discuss., 9, 19471-19507, doi:10.5194/acpd-9-19471-2009, 2009.
 
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