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| Titel |
Brightening of the global cloud field by nitric acid and the associated radiative forcing |
| VerfasserIn |
R. Makkonen, S. Romakkaniemi, H. Kokkola, P. Stier, P. Räisänen, S. Rast, J. Feichter, M. Kulmala  , A. Laaksonen |
| 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. 16 ; Nr. 12, no. 16 (2012-08-22), S.7625-7633 |
| Datensatznummer |
250011407
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| Publikation (Nr.) |
 copernicus.org/acp-12-7625-2012.pdf |
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| Zusammenfassung |
| Clouds cool Earth's climate by reflecting 20% of the incoming solar energy,
while also trapping part of the outgoing radiation. The effect of human
activities on clouds is poorly understood, but the present-day anthropogenic
cooling via changes of cloud albedo and lifetime could be of the same order
as warming from anthropogenic addition in CO2. Soluble trace gases can
increase water condensation to particles, possibly leading to activation of
smaller aerosols and more numerous cloud droplets. We have studied the effect
of nitric acid on the aerosol indirect effect with the global aerosol-climate
model ECHAM5.5-HAM2. Including the nitric acid effect in the model increases
cloud droplet number concentrations globally by 7%. The nitric acid
contribution to the present-day cloud albedo effect was found to be
−0.32 W m−2 and to the total indirect effect −0.46 W m−2. The contribution
to the cloud albedo effect is shown to increase to −0.37 W m−2 by the
year 2100, if considering only the reductions in available cloud condensation
nuclei. Overall, the effect of nitric acid can play a large part in aerosol
cooling during the following decades with decreasing SO2 emissions and
increasing NOx and greenhouse gases. |
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