Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 15097-15117, 2016
http://www.atmos-chem-phys.net/16/15097/2016/
doi:10.5194/acp-16-15097-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Dec 2016
An observationally constrained estimate of global dust aerosol optical depth
David A. Ridley1, Colette L. Heald1, Jasper F. Kok2, and Chun Zhao3 1Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
2Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA, USA
3Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, Richland, WA 99352, USA
Abstract. The role of mineral dust in climate and ecosystems has been largely quantified using global climate and chemistry model simulations of dust emission, transport, and deposition. However, differences between these model simulations are substantial, with estimates of global dust aerosol optical depth (AOD) that vary by over a factor of 5. Here we develop an observationally based estimate of the global dust AOD, using multiple satellite platforms, in situ AOD observations and four state-of-the-science global models over 2004–2008. We estimate that the global dust AOD at 550 nm is 0.030 ± 0.005 (1σ), higher than the AeroCom model median (0.023) and substantially narrowing the uncertainty. The methodology used provides regional, seasonal dust AOD and the associated statistical uncertainty for key dust regions around the globe with which model dust schemes can be evaluated. Exploring the regional and seasonal differences in dust AOD between our observationally based estimate and the four models in this study, we find that emissions in Africa are often overrepresented at the expense of Asian and Middle Eastern emissions and that dust removal appears to be too rapid in most models.

Citation: Ridley, D. A., Heald, C. L., Kok, J. F., and Zhao, C.: An observationally constrained estimate of global dust aerosol optical depth, Atmos. Chem. Phys., 16, 15097-15117, doi:10.5194/acp-16-15097-2016, 2016.
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Short summary
Mineral dust aerosol affects climate through interaction with radiation and clouds, human health through contribution to particulate matter, and ecosystem health through nutrient transport and deposition. In this study, we use satellite and in situ retrievals to derive an observational estimate of the global dust AOD with which evaluate modeled dust AOD. Differences in the seasonality and regional distribution of dust AOD between observations and models are highlighted.
Mineral dust aerosol affects climate through interaction with radiation and clouds, human health...
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