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| Titel |
Technical Note: Characterization of a static thermal-gradient CCN counter |
| VerfasserIn |
G. P. Frank, U. Dusek, M. O. Andreae |
| 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 ; 7, no. 12 ; Nr. 7, no. 12 (2007-06-15), S.3071-3080 |
| Datensatznummer |
250005080
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| Publikation (Nr.) |
 copernicus.org/acp-7-3071-2007.pdf |
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| Zusammenfassung |
The static (parallel-plate thermal-gradient) diffusion chamber (SDC) was one
of the first instruments designed to measure cloud condensation nuclei (CCN)
concentrations as a function of supersaturation. It has probably also been
the most widely used type of CCN counter. This paper describes the detailed
experimental characterization of a SDC CCN counter, including calibration
with respect to supersaturation and particle number concentration. In
addition, we investigated the proposed effect of lowered supersaturation
because of water vapor depletion with increasing particle concentration. The
results obtained give a better understanding why and in which way it is
necessary to calibrate the SDC CCN counter. The calibration method is
described in detail and can, in parts, be used for calibrations also for
other types of CCN counters.
We conclude the following: 1) it is important to experimentally calibrate
SDC CCN counters with respect to supersaturation, and not only base the
supersaturation on the theoretical description of the instrument; 2) the
number concentration calibration needs to be performed as a function of
supersaturation, also for SDC CCN counter using the photographic technique;
and 3) we observed no evidence that water vapor depletion lowered the
supersaturation. |
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