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| Titel |
Climatic effects of 1950-2050 changes in US anthropogenic aerosols – Part 1: Aerosol trends and radiative forcing |
| VerfasserIn |
E. M. Leibensperger, L. J. Mickley, D. J. Jacob, W.-T. Chen, J. H. Seinfeld, A. Nenes, P. J. Adams, D. G. Streets, N. Kumar, D. Rind |
| 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. 7 ; Nr. 12, no. 7 (2012-04-10), S.3333-3348 |
| Datensatznummer |
250011015
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| Publikation (Nr.) |
 copernicus.org/acp-12-3333-2012.pdf |
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| Zusammenfassung |
| We calculate decadal aerosol direct and indirect (warm cloud) radiative
forcings from US anthropogenic sources over the 1950–2050 period. Past and
future aerosol distributions are constructed using GEOS-Chem and historical
emission inventories and future projections from the IPCC A1B scenario.
Aerosol simulations are evaluated with observed spatial distributions and
1980–2010 trends of aerosol concentrations and wet deposition in the
contiguous US. Direct and indirect radiative forcing is calculated using the
GISS general circulation model and monthly mean aerosol distributions from
GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly
localized over the eastern US. We find that its magnitude peaked in
1970–1990, with values over the eastern US (east of 100° W) of −2.0 W m−2
for direct forcing including contributions from sulfate (−2.0 W m−2), nitrate
(−0.2 W m−2), organic carbon (−0.2 W m−2), and
black carbon (+0.4 W m−2). The uncertainties in radiative forcing due
to aerosol radiative properties are estimated to be about 50%. The
aerosol indirect effect is estimated to be of comparable magnitude to the
direct forcing. We find that the magnitude of the forcing declined sharply
from 1990 to 2010 (by 0.8 W m−2 direct and 1.0 W m−2 indirect),
mainly reflecting decreases in SO2 emissions, and project that it will
continue declining post-2010 but at a much slower rate since US SO2
emissions have already declined by almost 60% from their peak. This
suggests that much of the warming effect of reducing US anthropogenic
aerosol sources has already been realized. The small positive radiative
forcing from US BC emissions (+0.3 W m−2 over the eastern US in 2010;
5% of the global forcing from anthropogenic BC emissions worldwide)
suggests that a US emission control strategy focused on BC would have only
limited climate benefit. |
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