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| Titel |
Variations of cloud condensation nuclei (CCN) and aerosol activity during fog–haze episode: a case study from Shanghai |
| VerfasserIn |
C. Leng, Q. Zhang, D. Zhang, C. Xu, T. Cheng, R. Zhang, J. Tao, J. Chen, S. Zha, Y. Zhang, X. Li, L. Kong, W. Gao |
| 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 ; 14, no. 22 ; Nr. 14, no. 22 (2014-11-27), S.12499-12512 |
| Datensatznummer |
250119193
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| Publikation (Nr.) |
 copernicus.org/acp-14-12499-2014.pdf |
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| Zusammenfassung |
| Measurements of cloud condensation nuclei (CCN), condensation nuclei (CN)
and aerosol chemical composition were performed simultaneously at an urban
site in Shanghai from 6 to 9 November 2010. The variations of CCN number
concentration (NCCN) and aerosol activity (activated aerosol fraction,
NCCN/NCN) were examined during a fog–haze co-occurring event.
Anthropogenic pollutants emitted from vehicles and unfavorable
meteorological conditions such as low planetary boundary layer (PBL) height
exerted a great influence on PM2.5 and black carbon (BC) loadings.
NCCN at 0.2% supersaturation (SS) mostly fell in the range of 994 to
6268 cm−3, and the corresponding NCCN/NCN varied between 0.09
and 0.57. NCCN and NCCN/NCN usually were usually higher in
the hazy case due to increased aerosol concentration in the accumulation
mode (100–500 nm), and lower in the foggy–hazy and clear cases. The BC mass
concentration posed a strong positive effect on NCCN in the
foggy–hazy and hazy cases, whereas it poorly correlated with NCCN in
the clear case. NCCN/NCN was weakly related with BC in both
foggy–hazy and hazy cases. By using a simplified particle hygroscopicity
(κ), the calculated critical dry size (CDS) of activated aerosol did
not exceed 130 nm at 0.2% SS in spite of diverse aerosol chemical
compositions. The predicted NCCN at 0.2% SS was very successful
compared with the observed NCCN in clear case (R2=0.96) and
foggy–hazy/hazy cases (R2=0.91). In addition, their corresponding
ratios of predicted to observed NCCNwere on average 0.95 and 0.92,
respectively. More organic matter is possibly responsible for this closure
difference between foggy–hazy/hazy and clear cases. These results reveal
that the particulate pollutant burden exerts a significant impact on
NCCN, especially NCCN/NCN promotes effectively during the
polluted periods. |
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