Atmos. Chem. Phys. Discuss., 8, 18765-18802, 2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
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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.
Development of a global model of mineral dust aerosol microphysics
Y. H. Lee1, K. Chen2, and P. J. Adams1,3
1Dept. of Civil and Environmental Engineering, Carnegie Mellon Univ., Pittsburgh, PA, USA
2Vermilion Asset Management, New York, NY, USA
3Dept. of Engineering and Public Policy, Carnegie Mellon Univ., Pittsburgh, PA, USA

Abstract. A mineral dust module is developed and implemented into the global aerosol microphysics model, GISS-TOMAS. The model is evaluated against long-term measurements of dust surface mass concentrations and deposition fluxes. Predicted mass concentrations and deposition fluxes are in error on average by a factor of 3 and 5, respectively. The comparison shows that the model performs better near the dust source regions but underestimates surface concentrations and deposition fluxes in more remote regions. For example, including only sites with measured dust concentrations of at least 0.5 μg m−3, the model prediction agrees with observations to within a factor of 2. It was hypothesized that the lifetime of dust, 2.6 days in our base case, is too short and causes the underestimation in remote areas. However, a sensitivity simulation with smaller dust particles and increased lifetime, 3.7 days, does not significantly improve the comparison. We conclude that the underestimation of mineral dust in remote areas results from local factors and sources not well described by the dust source function and/or the GCM meteorology. The effect of dust aerosols on CCN(0.2%) concentrations is negligible in most regions of the globe; however, CCN(0.2%) concentrations decrease by 10–20% in dusty regions as a result of coagulational scavenging of CCN particles by dust and a decrease in H2SO4 condensation to CCN particles due to the additional surface area of dust.

Citation: Lee, Y. H., Chen, K., and Adams, P. J.: Development of a global model of mineral dust aerosol microphysics, Atmos. Chem. Phys. Discuss., 8, 18765-18802, doi:10.5194/acpd-8-18765-2008, 2008.
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