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| Titel |
Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by deciduous forest (Sapporo, northern Japan) during the summer of 2011 |
| VerfasserIn |
J. Jung, K. Kawamura |
| 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 ; 14, no. 14 ; Nr. 14, no. 14 (2014-07-24), S.7519-7531 |
| Datensatznummer |
250118904
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| Publikation (Nr.) |
 copernicus.org/acp-14-7519-2014.pdf |
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| Zusammenfassung |
| To investigate the hygroscopic properties of ultrafine particles during new
particle formation events, the hygroscopic growth factors of size-segregated
atmospheric particles were measured at an urban site in Sapporo, northern
Japan, during the summer of 2011. The hygroscopic growth factor at 85 %
relative humidity [g(85%)] of freshly formed nucleation mode particles was
1.11 to 1.28 (average: 1.16 ± 0.06) at a dry particle diameter
(Dp) centered on 20 nm, which is equivalent to 1.17 to 1.35
(1.23 ± 0.06) at a dry Dp centered on 100 nm after considering the
Kelvin effect. These values are comparable with those of secondary organic
aerosols, suggesting that low-volatility organic vapors are important to the
burst of nucleation mode particles. The equivalent g(85%) at a dry
Dp of 100 nm for nucleated particles that have grown to Aitken mode
sizes (1.24 to 1.34; average: 1.30 ± 0.04) were slightly higher than
those of newly formed nucleation mode particles, suggesting that the growth
of freshly formed nucleation mode particles to the Aitken mode size can be
subjected to condensation of not only low-volatility organic vapors, but
also water-soluble inorganic species. Based on this result, and previous
measurement of radiocarbon in aerosols, we suggest that the burst of
nucleation mode particles and their subsequent growth were highly affected
by biogenic organic emissions at this measurement site, which is surrounded
by deciduous forest. Gradual increases in mode diameter after the burst of
nucleation mode particles were observed under southerly wind conditions,
with a dominant contribution of intermediately hygroscopic particles.
However, sharp increases in mode diameter were observed when the wind
direction shifted to northwesterly or northeasterly, with a sharp increase
in the highly hygroscopic particle fraction of the Aitken mode particles,
indicating that the hygroscopic growth factor of newly formed particles is
perturbed by the local winds that deliver different air masses to the
measurement site. |
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