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| Titel |
Light absorption by pollution, dust, and biomass burning aerosols: a global model study and evaluation with AERONET measurements |
| VerfasserIn |
Mian Chin, T. Diehl, O. Dubovik, T. F. Eck, B. N. Holben, A. Sinyuk, D. G. Streets |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 9 ; Nr. 27, no. 9 (2009-09-02), S.3439-3464 |
| Datensatznummer |
250016641
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3439-2009.pdf |
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| Zusammenfassung |
| Atmospheric aerosol distributions from 2000 to 2007 are simulated with the
Goddard Chemistry Aerosol Radiation and Transport (GOCART) model to
attribute light absorption by aerosol to its composition and sources from
pollution, dust, and biomass burning. The 8-year, global averaged total
aerosol optical depth (τ), absorption optical depth (τa), and single
scattering albedo (ω) at 550 nm are estimated at 0.14, 0.0086, and 0.95,
respectively, with sulfate making the largest fraction of τ (37%),
followed by dust (30%), sea salt (16%), organic matter (OM) (13%),
and black carbon (BC) (4%). BC and dust account for 43% and 53% of
τa, respectively. From a model experiment with "tagged" sources,
natural aerosols are estimated to be 58% of τ and 53% of τa, with
pollution and biomass burning aerosols to share the rest. Comparing with
data from the surface sunphotometer network AERONET, the model tends to
reproduce much better the AERONET direct measured data of τ and the Ångström exponent (α) than its
retrieved quantities of ω and τa. Relatively small in its systematic bias
of τ for pollution and dust regions, the model tends to underestimate τ for
biomass burning aerosols by 30–40%. The modeled α is 0.2–0.3 too low
(particle too large) for pollution and dust aerosols but 0.2–0.3 too high
(particle too small) for the biomass burning aerosols, indicating errors in
particle size distributions in the model. Still, the model estimated
ω is lower in dust regions and shows a much stronger wavelength dependence
for biomass burning aerosols but a weaker one for pollution aerosols than
those quantities from AERONET. These comparisons necessitate model
improvements on aerosol size distributions, the refractive indices of dust
and black carbon aerosols, and biomass burning emissions in order to better
quantify the aerosol absorption in the atmosphere. |
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