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| Titel |
New particle growth and shrinkage observed in subtropical environments |
| VerfasserIn |
L.-H. Young, S.-H. Lee, V. P. Kanawade, T.-C. Hsiao, Y. L. Lee, B.-F. Hwang, Y.-J. Liou, H.-T. Hsu, P.-J. Tsai |
| 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 ; 13, no. 2 ; Nr. 13, no. 2 (2013-01-16), S.547-564 |
| Datensatznummer |
250017587
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| Publikation (Nr.) |
 copernicus.org/acp-13-547-2013.pdf |
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| Zusammenfassung |
| We present the first systematic analysis for new particle formation (NPF),
growth and shrinkage of new particles at four different sites in
subtropical central Taiwan. A total of 14 NPF events were identified from
137 days of ambient measurements during a cold and warm season. The measured
formation rates of 10 nm particles (J10) and growth rates were in the
range of 4.4–30 cm−3 s−1 and 7.4–24 nm h−1, respectively. The
onset of NPF events coincided with decreases of condensation sink (CS) and
increases of SO2 under enhanced atmospheric mixing and dilution.
However, the lower or comparable SO2 on event days than on non-event
days suggests that SO2 was not a limiting factor for NPF. On non-event
days, the particle number concentrations were mostly driven by traffic
emissions. We also observed shrinkage of new particles, the reversal of
growth, during five out of the identified secondary formation. UFP particles
events. In intense cases,
the grown particles shrank back to the smallest measurable size of
~10 nm, thereby creating a unique "arch-like" shape in the
size distribution contour plot. The particle shrinkage rates ranged from
−5.1 to −7.6 nm h−1. The corresponding particle volume losses suggest
that a notable fraction of the condensable species that contributed to
growth was semi-volatile. The particle shrinkage was related to enhanced
atmospheric dilution, high ambient temperature and low relative humidity,
thus favoring the evaporation of semi-volatile species from the particulate
phase to the gas phase. Our observations show that the new particle growth
could be a reversible process, in which the evaporating semi-volatile
species are important for the growth of new particles to sizes of
environmental health concerns. |
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