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| Titel |
An intensive study of aerosol optical properties in Beijing urban area |
| VerfasserIn |
X. He, C. C. Li, A. K. H. Lau, Z. Z. Deng, J. T. Mao, M. H. Wang, X. Y. Liu |
| 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 ; 9, no. 22 ; Nr. 9, no. 22 (2009-11-26), S.8903-8915 |
| Datensatznummer |
250007767
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| Publikation (Nr.) |
 copernicus.org/acp-9-8903-2009.pdf |
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| Zusammenfassung |
| In order to quantify the aerosol impact on climate, a range of aerosol
parameters are required. In this paper, two-year of ground-based
observations of aerosol optical properties from an urban site in Beijing of
China are assessed. The aerosol absorption coefficient (σa), scattering
coefficient (σs), as well as single scattering albedo (ω) are analyzed to
aid in characterizing Beijing's urban aerosol. Two-year averages (and
standard deviations) for σa at 532 nm, σs at 525 nm and ω at 525 nm
are 56±49 Mm−1, 288±281 Mm−1 and 0.80±0.09,
respectively. Meanwhile, there is a distinct diurnal variation for σa,
with its minimum occurring at approximately 14:00 to 15:00 and maximum at
midnight. σs peaks in the late morning and the minimum occurs in the
evening. σs in summer is higher than that in winter. ω is also higher in
summer than that in winter, except before 07:00 a.m., and peaks in the early
afternoon. Both σa and σs show strong dependence on local wind in
all four seasons. When the wind blows from the north with low speed (0–2 m/s),
the values of σa are high, and in contrast, very low with wind
speeds higher than 4 m/s. When the wind blows from south with low speed
(0–4 m/s), σa is intermediate. The patterns of the wind dependence of
σa indicates that σa is mainly dominated by local emissions. σs
displays a similar dependence on wind speed and direction to σa, except
in summer. In summer, the σs value is highest when wind is from
southeast with speed of 0–6 m/s. This indicates that the particle pollution
resulting from regional transport is only significant in the summer season.
ω also shows wind dependence to some extent though not as strong as σa or
σs. Overall, the wind dependence results provide valuable information
about the locations of aerosol pollution sources and suggest that the air
pollution in summer is a regional problem but in other seasons it is mainly
affected by local urban emissions. |
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