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| Titel |
Size and time-resolved growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei |
| VerfasserIn |
C. Kuang, M. Chen, J. Zhao, J. Smith, P. H. McMurry, J. Wang |
| 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 ; 12, no. 7 ; Nr. 12, no. 7 (2012-04-12), S.3573-3589 |
| Datensatznummer |
250011028
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| Publikation (Nr.) |
 copernicus.org/acp-12-3573-2012.pdf |
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| Zusammenfassung |
| This study presents measurements of size and time-resolved particle diameter
growth rates for freshly nucleated particles down to 1 nm geometric
diameter. Novel data analysis methods were developed, de-coupling for the
first time the size and time-dependence of particle growth rates by fitting
the aerosol general dynamic equation to size distributions obtained at an
instant in time. Size distributions of freshly nucleated total aerosol
(neutral and charged) were measured during two intensive measurement
campaigns in different environments (Atlanta, GA and Boulder, CO) using a
recently developed electrical mobility spectrometer with a diethylene
glycol-based ultrafine condensation particle counter as the particle
detector. One new particle formation (NPF) event from each campaign was
analyzed in detail. At a given instant in time during the NPF event,
size-resolved growth rates were obtained directly from measured size
distributions and were found to increase approximately linearly with
particle size from ~1 to 3 nm geometric diameter, increasing from
5.5 ± 0.8 to 7.6 ± 0.6 nm h−1 in Atlanta (13:00) and from
5.6 ± 2 to 27 ± 5 nm h−1 in Boulder (13:00). The resulting growth
rate enhancement Γ, defined as the ratio of the observed growth rate
to the growth rate due to the condensation of sulfuric acid only, was found
to increase approximately linearly with size from ~1 to 3 nm
geometric diameter. For the presented NPF events, values for Γ had
lower limits that approached ~1 at 1.2 nm geometric diameter in
Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and had upper
limits that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at
2.7 nm geometric diameter in Boulder. Nucleated particle survival
probability calculations comparing the effects of constant and
size-dependent growth indicate that neglecting the strong dependence of
growth rate on size from 1 to 3 nm observed in this study could lead to a
significant overestimation of CCN survival probability. |
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