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| Titel |
Characterization of photochemical pollution at different elevations in mountainous areas in Hong Kong |
| VerfasserIn |
H. Guo, Z. H. Ling, K. Cheung, F. Jiang, D. W. Wang, I. J. Simpson, B. Barletta, S. Meinardi, T. J. Wang, X. M. Wang, S. M. Saunders, D. R. Blake |
| 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. 8 ; Nr. 13, no. 8 (2013-04-16), S.3881-3898 |
| Datensatznummer |
250018587
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| Publikation (Nr.) |
 copernicus.org/acp-13-3881-2013.pdf |
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| Zusammenfassung |
| To advance our understanding on the factors that affect photochemical
pollution at different elevations in mountainous areas, concurrent
systematic field measurements (September to November 2010) were conducted at
a mountain site and at an urban site at the foot of the mountain in Hong
Kong. The mixing ratios of air pollutants were greater at the foot of the
mountain (i.e., Tsuen Wan urban site, TW) than near the summit (i.e., Tai Mao
Shan mountain site, TMS), expect for ozone. In total, only one O3
episode day was observed at TW, whereas twenty-one (21) O3 episode days were
observed at TMS. The discrepancy of O3 at the two sites was attributed
to the mixed effects of NO titration, vertical meteorological conditions,
regional transport and mesoscale circulations. The lower NO levels at TMS
and the smaller differences of "oxidant" Ox (O3 + NO2)
between the two sites suggested that variations of O3 at the two sites
were partly attributed to different degree of NO titration. In addition,
analysis of vertical structure of meteorological variables revealed that the
inversion layer at the range of altitudes of 500–1000 m
might be another factor that caused the high O3 levels at TMS.
Furthermore, analyses of the wind fields, the levels of air pollutants in
different air flows, ratios of different trace gases and the correlation
between variability and the lifetime of VOCs (volatile organic compounds) indicated that high O3
concentrations at TMS were somewhat influenced by regional air masses from
the highly polluted Pearl River delta (PRD) region. In particular, the
diurnal profiles and correlations of gaseous pollutants suggested influence
of mesoscale circulations, which is confirmed using the Master Chemical
Mechanism moving box model (Mbox) and the Weather Research and Forecasting
(WRF) model. By investigating the correlations of observed O3 and
NOx* and the relationships of O3 and its precursors by
an observation-based model (OBM), as well as the ratios of
VOC/NOx,
it was concluded that photochemical O3 formation at TMS was mostly
influenced by VOCs, with measurable impact of NOx, while O3
production at TW was generally limited by the concentrations of VOCs. This
is the first report of the comprehensive analysis on the data of
photochemical pollution obtained from concurrent measurements in mountainous
areas in the PRD region. |
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