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| Titel |
Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM |
| VerfasserIn |
Karsten Peters, P. Stier, J. Quaas, H. Grassl |
| 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 ; 12, no. 13 ; Nr. 12, no. 13 (2012-07-13), S.5985-6007 |
| Datensatznummer |
250011310
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| Publikation (Nr.) |
 copernicus.org/acp-12-5985-2012.pdf |
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| Zusammenfassung |
In this study, we employ the global aerosol-climate model ECHAM-HAM to
globally assess aerosol indirect effects (AIEs) resulting from shipping
emissions of aerosols and aerosol precursor gases. We implement shipping
emissions of sulphur dioxide (SO2), black carbon (BC) and particulate
organic matter (POM) for the year 2000 into the model and quantify the
model's sensitivity towards uncertainties associated with the emission
parameterisation as well as with the shipping emissions themselves.
Sensitivity experiments are designed to investigate (i) the uncertainty in
the size distribution of emitted particles, (ii) the uncertainty associated
with the total amount of emissions, and (iii) the impact of reducing
carbonaceous emissions from ships.
We use the results from one sensitivity experiment for a detailed discussion
of shipping-induced changes in the global aerosol system as well as the
resulting impact on cloud properties. From all sensitivity experiments, we
find AIEs from shipping emissions to range from −0.32 ± 0.01 W m−2 to
−0.07 ± 0.01 W m−2 (global mean value and inter-annual variability as a
standard deviation). The magnitude of the AIEs depends much more on the
assumed emission size distribution and subsequent aerosol microphysical
interactions than on the magnitude of the emissions themselves. It is
important to note that although the strongest estimate of AIEs from shipping
emissions in this study is relatively large, still much larger estimates have
been reported in the literature before on the basis of modelling studies. We
find that omitting just carbonaceous particle emissions from ships favours
new particle formation in the boundary layer. These newly formed particles
contribute just about as much to the CCN budget as the carbonaceous particles
would, leaving the globally averaged AIEs nearly unaltered compared to a
simulation including carbonaceous particle emissions from ships. |
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