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Technical Note: Characterization of a static thermal-gradient CCN counter

Frank, Göran LU ; Dusek, Ulrike and Andreae, Meinrat O. (2007) In Atmospheric Chemistry and Physics 7(12). p.3071-3080
Abstract
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... (More)
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. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Atmospheric Chemistry and Physics
volume
7
issue
12
pages
3071 - 3080
publisher
Copernicus Gesellschaft Mbh
external identifiers
  • scopus:34250785703
ISSN
1680-7324
language
English
LU publication?
no
id
d4c06a5c-461d-4616-a80f-b57a7add11ea (old id 772118)
alternative location
http://www.atmos-chem-phys.net/7/3071/2007/acp-7-3071-2007.html
date added to LUP
2007-12-19 08:45:27
date last changed
2017-01-01 04:58:04
@article{d4c06a5c-461d-4616-a80f-b57a7add11ea,
  abstract     = {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. <br/><br>
<br/><br>
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.},
  author       = {Frank, Göran and Dusek, Ulrike and Andreae, Meinrat O.},
  issn         = {1680-7324},
  language     = {eng},
  number       = {12},
  pages        = {3071--3080},
  publisher    = {Copernicus Gesellschaft Mbh},
  series       = {Atmospheric Chemistry and Physics},
  title        = {Technical Note: Characterization of a static thermal-gradient CCN counter},
  volume       = {7},
  year         = {2007},
}