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Titel |
Observation of aerosol size distribution and new particle formation at a mountain site in subtropical Hong Kong |
VerfasserIn |
H. Guo, D. W. Wang, K. Cheung, Z. H. Ling, C. K. Chan, X. H. Yao |
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. 20 ; Nr. 12, no. 20 (2012-10-30), S.9923-9939 |
Datensatznummer |
250011544
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Publikation (Nr.) |
copernicus.org/acp-12-9923-2012.pdf |
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Zusammenfassung |
In order to investigate the formation and growth processes of nucleation
mode particles, and to quantify the particle number (PN) concentration and
size distributions in Hong Kong, an intensive field measurement was
conducted from 25 October to 29 November in 2010 near the mountain summit of
Tai Mo Shan, a suburban site approximately the geographical centre of the
New Territories in Hong Kong. Based on observations of the particle size
distribution, new particle formation (NPF) events were found on 12 out of 35
days with the estimated formation rate J5.5 from 0.97 to 10.2 cm−3 s−1,
and the average growth rates from 1.5 to 8.4 nm h−1. The
events usually began at 10:00–11:00 LT characterized by the
occurrence of a nucleation mode with a peak diameter of 6–10 nm. Solar
radiation, wind speed, sulfur dioxide (SO2) and ozone (O3)
concentrations were on average higher, whereas temperature, relative
humidity and daytime nitrogen dioxide (NO2) concentration were lower on
NPF days than on non-NPF days. Back trajectory analysis suggested that in
majority of the NPF event days, the air masses originated from the northwest
to northeast directions. The concentrations of gaseous sulfuric acid (SA)
showed good power-law relationship with formation rates, with exponents
ranging from 1 to 2. The result suggests that the cluster activation theory
and kinetic nucleation could potentially explain the observed NPF events in
this mountainous atmosphere of Hong Kong. Meanwhile, in these NPF events,
the contribution of sulfuric acid vapor to particle growth rate
(GR5.5–25) ranged from 9.2 to 52.5% with an average of 26%.
Measurement-based calculated oxidation rates of monoterpenes (i.e. α-pinene,
β-pinene, myrcene and limonene) by O3 positively correlated with the
GR5.5–25 (R = 0.80, p < 0.05). The observed associations of the
estimated formation rate J5.5 and the growth rate GR5.5–25 with
gaseous sulfuric acid and volatile organic compounds (VOCs) suggested the
critical roles of sulfuric acid and biogenic VOCs (e.g. α-pinene and
β-pinene) in these NPF events. |
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