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| Titel |
Technical Note: Using DEG-CPCs at upper tropospheric temperatures |
| VerfasserIn |
D. Wimmer, K. Lehtipalo, T. Nieminen, J. Duplissy, S. Ehrhart, J. Almeida, L. Rondo, A. Franchin, F. Kreissl, F. Bianchi, H. E. Manninen, M. Kulmala  , J. Curtius, T. Petäjä |
| 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 ; 15, no. 13 ; Nr. 15, no. 13 (2015-07-13), S.7547-7555 |
| Datensatznummer |
250119887
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| Publikation (Nr.) |
 copernicus.org/acp-15-7547-2015.pdf |
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| Zusammenfassung |
| Over the last few years, several condensation particle counters (CPCs) capable
of measuring in the sub-3 nm size range have been developed. Here we study
the performance of CPCs based on diethylene glycol (DEG) at different
temperatures during Cosmics Leaving OUtdoor Droplets (CLOUD) measurements at
CERN. The data shown here are the first set of verification measurements for
sub-3 nm CPCs under upper tropospheric temperatures using atmospherically
relevant aerosol particles. To put the results in perspective we calibrated
the DEG-CPC at room temperature, resulting in a cut-off diameter of
1.4 nm. All diameters refer to mobility equivalent diameters in this
paper. At upper tropospheric temperatures ranging from 246.15 K
to 207.15 K, we found cut-off sizes relative to a particle size magnifier in the range of
2.5 to 2.8 nm. Due to low number concentration after size classification,
the cut-off diameters have a high uncertainty (±0.3 nm)
associated with them. Operating two laminar flow DEG-CPCs with different
cut-off sizes together with other aerosol instruments, we looked at the
growth rates of aerosol population in the CLOUD chamber for particles smaller
than 10 nm at different temperatures. A more consistent picture emerged when
we normalized the growth rates to a fixed gas-phase sulfuric acid
concentration. All of the instruments detected larger growth rates at lower
temperatures, and the observed growth rates decreased as a function of
temperature, showing a similar trend for all instruments. The theoretical
calculations had a similar but much smaller temperature dependency. |
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