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| Titel |
A closure study of cloud condensation nuclei in the North China Plain using droplet kinetic condensational growth model |
| VerfasserIn |
F. Yang, H. Xue, Z. Deng, C. Zhao, Q. Zhang |
| 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. 12 ; Nr. 12, no. 12 (2012-06-22), S.5399-5411 |
| Datensatznummer |
250011276
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| Publikation (Nr.) |
 copernicus.org/acp-12-5399-2012.pdf |
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| Zusammenfassung |
| Aerosol size distribution and cloud condensation nucleus (CCN) number
concentration were measured in the North China Plain from 31 December 2009
to 20 January 2010. The CCN closure study was performed using these data and
droplet kinetic condensational growth model. The calculated CCN
concentration with the assumption of pure ammonium sulfate aerosol is
40–140% higher than that observed for the supersaturations in this study.
A sensitivity test on aerosol solubility and mixing state indicates that 0.2–0.5
mass fraction of ammonium sulfate for internal mixture can lead to a
ratio of 0.82–1.30 for the calculated to observed CCN concentrations, and that
0.4–0.7 mass fraction of ammonium sulfate for external mixture results in
a ratio of 0.74–1.25 in the North China Plain during the time period of the
field observations, suggesting that a relatively simple scheme may be used
for CCN prediction in climate models for this region. Finally, we compare
the calculated CCN concentrations from the kinetic condensational growth
model and the equilibrium model. The kinetic condensational growth model can
simulate droplet growth in a time period under a certain supersaturation,
while the equilibrium model only predicts whether a certain aerosol can be
activated as CCN under that supersaturation. The CCN concentration
calculated with the kinetic model is higher than that with the equilibrium
model at supersaturations of 0.056% and 0.083%, because some particles
that are not activated from the equilibrium point-of-view can grow large
enough to be considered as CCN in the kinetic model. While at a
supersaturation of 0.17%, CCN concentration calculated with the kinetic
model is lower than that with the equilibrium model, due to the limitation
of droplet kinetic growth. The calculated CCN concentrations using the
kinetic model and the equilibrium model are the same at supersaturations of
0.35% and 0.70%. |
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