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| Titel |
Impacts of aerosol-cloud interactions on past and future changes in tropospheric composition |
| VerfasserIn |
N. Unger, S. Menon, D. M. Koch, D. T. Shindell  |
| 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 ; 9, no. 12 ; Nr. 9, no. 12 (2009-06-22), S.4115-4129 |
| Datensatznummer |
250007439
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| Publikation (Nr.) |
 copernicus.org/acp-9-4115-2009.pdf |
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| Zusammenfassung |
| The development of effective emissions control policies that are beneficial
to both climate and air quality requires a detailed understanding of all the
feedbacks in the atmospheric composition and climate system. We perform
sensitivity studies with a global atmospheric composition-climate model to
assess the impact of aerosols on tropospheric chemistry through their
modification on clouds, aerosol-cloud interactions (ACI). The model includes
coupling between both tropospheric gas-phase and aerosol chemistry and
aerosols and liquid-phase clouds. We investigate past impacts from
preindustrial (PI) to present day (PD) and future impacts from PD to 2050
(for the moderate IPCC A1B scenario) that embrace a wide spectrum of
precursor emission changes and consequential ACI. The aerosol indirect
effect (AIE) is estimated to be −2.0 Wm−2 for PD-PI and −0.6 Wm−2
for 2050-PD, at the high end of current estimates. Inclusion of
ACI substantially impacts changes in global mean methane lifetime across
both time periods, enhancing the past and future increases by 10% and
30%, respectively. In regions where pollution emissions increase,
inclusion of ACI leads to 20% enhancements in in-cloud sulfate production
and ~10% enhancements in sulfate wet deposition that is displaced
away from the immediate source regions. The enhanced in-cloud sulfate
formation leads to larger increases in surface sulfate across polluted
regions (~10–30%). Nitric acid wet deposition is dampened by
15–20% across the industrialized regions due to ACI allowing additional
re-release of reactive nitrogen that contributes to 1–2 ppbv increases in
surface ozone in outflow regions. Our model findings indicate that ACI must
be considered in studies of methane trends and projections of future changes
to particulate matter air quality. |
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