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| Titel |
Sulfur cycle and sulfate radiative forcing simulated from a coupled global climate-chemistry model |
| VerfasserIn |
I.-C. Tsai, J.-P. Chen, P.-Y. Lin, W.-C. Wang, I. S. A. Isaksen |
| 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 ; 10, no. 8 ; Nr. 10, no. 8 (2010-04-21), S.3693-3709 |
| Datensatznummer |
250008366
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| Publikation (Nr.) |
 copernicus.org/acp-10-3693-2010.pdf |
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| Zusammenfassung |
| The sulfur cycle and radiative effects of sulfate aerosol on climate are
studied with a Global tropospheric Climate-Chemistry Model in which
chemistry, radiation and dynamics are fully coupled. Production and removal
mechanisms of sulfate are analyzed for the conditions of natural and
anthropogenic sulfur emissions. Results show that the 1985 anthropogenic
emission tripled the global SO2 and sulfate loadings from its natural
value of 0.16 and 0.10 Tg S, respectively. Under natural conditions, the
fraction of sulfate produced in-cloud is 74%; whereas with anthropogenic
emissions, the fraction of in-cloud sulfate production slightly increased to
76%. Lifetimes of SO2 and sulfate under polluted conditions are
estimated to be 1.7 and 2.0 days, respectively. The tripling of sulfate
results in a direct radiative forcing of −0.43 W m−2 (clear-sky) or
−0.24 W m−2 (all-sky), and a significant first indirect forcing of
−1.85 W m−2, leading to a mean global cooling of about 0.1 K. Regional
forcing and responses are significantly stronger than the global values. The
first indirect forcing is sensitive to the relationship between aerosol
concentration and cloud droplet number concentration which requires further
investigation. Two aspects of chemistry-climate interaction are addressed.
Firstly, the coupling effects lead to a slight decrease of 1% in global
sulfate loading for both the cases of natural and anthropogenic added sulfur
emissions. Secondly, only the indirect effect of sulfate aerosols yields
significantly stronger signals in changes of near surface temperature and
sulfate loading than changes due to intrinsic climate variability, while
other responses to the indirect effect and all responses to the direct
effect are below noise level. |
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