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| Titel |
Change in global aerosol composition since preindustrial times |
| VerfasserIn |
K. Tsigaridis, M. Krol, F. J. Dentener, Y. Balkanski, J. Lathière, S. Metzger, D. A. Hauglustaine, M. Kanakidou |
| 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 ; 6, no. 12 ; Nr. 6, no. 12 (2006-11-10), S.5143-5162 |
| Datensatznummer |
250004175
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| Publikation (Nr.) |
 copernicus.org/acp-6-5143-2006.pdf |
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| Zusammenfassung |
| To elucidate human induced changes of aerosol load and composition in the
atmosphere, a coupled aerosol and gas-phase chemistry transport model of the
troposphere and lower stratosphere has been used. The present 3-D modeling
study focuses on aerosol chemical composition change since preindustrial
times considering the secondary organic aerosol formation together with all
other main aerosol components including nitrate. In particular, we evaluate
non-sea-salt sulfate (nss-SO4=), ammonium (NH4+),
nitrate (NO3−), black carbon (BC), sea-salt, dust, primary and
secondary organics (POA and SOA) with a focus on the importance of secondary
organic aerosols. Our calculations show that the aerosol optical depth (AOD)
has increased by about 21% since preindustrial times. This enhancement of
AOD is attributed to a rise in the atmospheric load of BC,
nss-SO4=, NO3, POA and SOA by factors of 3.3, 2.6, 2.7,
2.3 and 1.2, respectively, whereas we assumed that the natural dust and
sea-salt sources remained constant. The nowadays increase in carbonaceous
aerosol loading is dampened by a 34–42% faster conversion of hydrophobic
to hydrophilic carbonaceous aerosol leading to higher removal rates. These
changes between the various aerosol components resulted in significant
modifications of the aerosol chemical composition. The relative importance
of the various aerosol components is critical for the aerosol climatic
effect, since atmospheric aerosols behave differently when their chemical
composition changes. According to this study, the aerosol composition
changed significantly over the different continents and with height since
preindustrial times. The presence of anthropogenically emitted primary
particles in the atmosphere facilitates the condensation of the
semi-volatile species that form SOA onto the aerosol phase, particularly in
the boundary layer. The SOA burden that is dominated by the natural
component has increased by 24% while its contribution to the AOD has
increased by 11%. The increase in oxidant levels and preexisting aerosol
mass since preindustrial times is the reason of the burden change, since
emissions have not changed significantly. The computed aerosol composition
changes translate into about 2.5 times more water associated with non
sea-salt aerosol. Additionally, aerosols contain 2.7 times more inorganic
components nowadays than during the preindustrial times. We find that the
increase in emissions of inorganic aerosol precursors is much larger than
the corresponding aerosol increase, reflecting a non-linear atmospheric
response. |
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