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| Titel |
The effect of sea ice loss on sea salt aerosol concentrations and the radiative balance in the Arctic |
| VerfasserIn |
H. Struthers, A. M. L. Ekman, P. Glantz, T. Iversen, A. Kirkevåg, E. M. Mårtensson, Ø. Seland, E. D. Nilsson |
| 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 ; 11, no. 7 ; Nr. 11, no. 7 (2011-04-13), S.3459-3477 |
| Datensatznummer |
250009605
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| Publikation (Nr.) |
 copernicus.org/acp-11-3459-2011.pdf |
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| Zusammenfassung |
| Understanding Arctic climate change requires knowledge of both the external
and the local drivers of Arctic climate as well as local feedbacks within the
system. An Arctic feedback mechanism relating changes in sea ice extent to an
alteration of the emission of sea salt aerosol and the consequent change in
radiative balance is examined. A set of idealized climate model simulations
were performed to quantify the radiative effects of changes in sea salt
aerosol emissions induced by prescribed changes in sea ice extent. The model
was forced using sea ice concentrations consistent with present day
conditions and projections of sea ice extent for 2100. Sea salt aerosol
emissions increase in response to a decrease in sea ice, the model results
showing an annual average increase in number emission over the polar cap
(70–90° N) of 86 × 106 m−2 s−1 (mass emission
increase of 23 μg m−2 s−1). This in turn leads to an
increase in the natural aerosol optical depth of approximately 23%. In
response to changes in aerosol optical depth, the natural component of the
aerosol direct forcing over the Arctic polar cap is estimated to be between
−0.2 and −0.4 W m−2 for the summer months, which results in a
negative feedback on the system. The model predicts that the change in first
indirect aerosol effect (cloud albedo effect) is approximately a factor of
ten greater than the change in direct aerosol forcing although this result is
highly uncertain due to the crude representation of Arctic clouds and
aerosol-cloud interactions in the model. This study shows that both the
natural aerosol direct and first indirect effects are strongly dependent on
the surface albedo, highlighting the strong coupling between sea ice,
aerosols, Arctic clouds and their radiative effects. |
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