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| Titel |
Aerosol mass spectrometer constraint on the global secondary organic aerosol budget |
| VerfasserIn |
D. V. Spracklen, J. L. Jimenez, K. S. Carslaw, D. R. Worsnop, M. J. Evans, G. W. Mann, Q. Zhang, M. R. Canagaratna, J. Allan, H. Coe, G. McFiggans, A. Rap, P. Forster |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 23 ; Nr. 11, no. 23 (2011-12-07), S.12109-12136 |
| Datensatznummer |
250010240
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| Publikation (Nr.) |
 copernicus.org/acp-11-12109-2011.pdf |
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| Zusammenfassung |
| The budget of atmospheric secondary organic aerosol (SOA) is very
uncertain, with recent estimates suggesting a global source of between
12 and 1820 Tg (SOA) a−1. We used a dataset of aerosol mass
spectrometer (AMS) observations from 34 different surface locations to
evaluate the GLOMAP global chemical transport model. The standard
model simulation (which included SOA from monoterpenes only)
underpredicted organic aerosol (OA) observed by the AMS and had little
skill reproducing the variability in the dataset. We simulated SOA
formation from biogenic (monoterpenes and isoprene), lumped
anthropogenic and lumped biomass burning volatile organic compounds
(VOCs) and varied the SOA yield from each precursor source to produce
the best overall match between model and observations. We assumed that
SOA is essentially non-volatile and condenses irreversibly onto
existing aerosol. Our best estimate of the SOA source is
140 Tg (SOA) a−1 but with a large uncertainty range which we
estimate to be 50–380 Tg (SOA) a−1. We found the minimum in
normalised mean error (NME) between model and the AMS dataset when we
assumed a large SOA source (100 Tg (SOA) a−1) from sources
that spatially matched anthropogenic pollution (which we term
antropogenically controlled SOA). We used organic carbon observations
compiled by Bahadur et al. (2009) to evaluate our estimated SOA
sources. We found that the model with a large anthropogenic SOA source
was the most consistent with these observations, however improvement
over the model with a large biogenic SOA source
(250 Tg (SOA) a−1) was small. We used a dataset of 14C
observations from rural locations to evaluate our estimated SOA
sources. We estimated a maximum of 10 Tg (SOA) a−1 (10 %) of
the anthropogenically controlled SOA source could be from fossil
(urban/industrial) sources. We suggest that an additional
anthropogenic source is most likely due to an anthropogenic pollution
enhancement of SOA formation from biogenic VOCs. Such an
anthropogenically controlled SOA source would result in substantial
climate forcing. We estimated a global mean aerosol direct effect of
−0.26 ± 0.15 Wm−2 and indirect (cloud albedo) effect
of −0.6+0.24−0.14 Wm−2 from anthropogenically
controlled SOA. The biogenic and biomass SOA sources are not well
constrained with this analysis due to the limited number of OA
observations in regions and periods strongly impacted by these
sources. To further improve the constraints by this method, additional
OA observations are needed in the tropics and the Southern Hemisphere. |
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