 |
| Titel |
Size-resolved and bulk activation properties of aerosols in the North China Plain |
| VerfasserIn |
Z. Z. Deng, C. S. Zhao, N. Ma, P. F. Liu, L. Ran, W. Y. Xu, J. Chen, Z. Liang, S. Liang, M. Y. Huang, X. C. Ma, Q. Zhang, J. N. Quan, P. Yan, S. Henning, K. Mildenberger, E. Sommerhage, M. Schäfer, F. Stratmann, A. Wiedensohler |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 8 ; Nr. 11, no. 8 (2011-04-27), S.3835-3846 |
| Datensatznummer |
250009653
|
| Publikation (Nr.) |
 copernicus.org/acp-11-3835-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
Size-resolved and bulk activation properties of aerosols were measured at a
regional/suburban site in the North China Plain (NCP), which is occasionally
heavily polluted by anthropogenic aerosol particles and gases. A Cloud
Condensation Nuclei (CCN) closure study is conducted with bulk CCN number
concentration (NCCN) and calculated CCN number concentration based on
the aerosol number size distribution and size-resolved activation
properties.
The observed CCN number concentration (NCCN-obs) are higher than those
observed in other locations than China, with average NCCN-obs of roughly
2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056,
0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry
diameter (Dm) is calculated based on the NCCN-obs and aerosol number
size distribution assuming homogeneous chemical composition. The inferred
cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and
50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with
their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively.
Size-resolved activation measurements show that most of the 300 nm particles
are activated at the investigated supersaturations, while almost no
particles of 30 nm are activated even at the highest supersaturation of
0.72%. The activation ratio increases with increasing supersaturation and
particle size. The slopes of the activation curves for ambient aerosols are
not as steep as those observed in calibrations with ammonium sulfate
suggesting that the observed aerosols is an external mixture of more
hygroscopic and hydrophobic particles.
The calculated CCN number concentrations (NCCN-calc) based on the
size-resolved activation ratio and aerosol number size distribution
correlate well with the NCCN-obs, and show an average overestimation of
19%. Sensitivity studies of the CCN closure show that the NCCN at
each supersaturation is well predicted with the campaign average of
size-resolved activation curves. These results indicate that the aerosol
number size distribution is critical in the prediction of possible CCN. The
CCN number concentration can be reliably estimated using time-averaged,
size-resolved activation efficiencies without accounting for the temporal
variations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|