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| Titel |
Modeling analysis of the seasonal characteristics of haze formation in Beijing |
| VerfasserIn |
X. Han, M. Zhang, J. Gao, S. Wang, F. Chai |
| 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. 18 ; Nr. 14, no. 18 (2014-09-25), S.10231-10248 |
| Datensatznummer |
250119066
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| Publikation (Nr.) |
 copernicus.org/acp-14-10231-2014.pdf |
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| Zusammenfassung |
| The air quality modeling system RAMS-CMAQ (Regional
Atmospheric Modeling System–Community Multiscale Air Quality), coupled with
an aerosol optical property scheme, was applied to simulate the
meteorological field, major aerosol components (sulfate, nitrate, ammonium,
black carbon, organic carbon, dust, and sea salt), and surface visibility
over the North China Plain (NCP) in 2011. The modeled results in February
and July 2011 were selected and analyzed to obtain an in-depth understanding
of the haze formation mechanism in Beijing for different seasons. The
simulation results showed that the visibility was below 10 km for most
regions of the NCP, and dropped to less than 5 km over the megacities of
Beijing and Tianjin, the whole of Hebei Province, and the northwest part of
Shandong Province during pollution episodes in February and July. The heavy
mass concentration of PM2.5 ranged from 120 to 300 μg m−3 and was concentrated in the areas with low visibility. The
haze formation mechanism in Beijing in winter was different from that in
summer. The mass concentration of PM2.5 was higher, and the components
more complicated, in winter. While the mass concentration of PM2.5 in
summer was lower than that in winter, the mass concentrations of hygroscopic
inorganic salts were comparable with those in winter, and the relative
humidity was, as expected, higher. Therefore, the water uptake of
hygroscopic aerosols played a key role in summer. Moreover, the analysis
showed that the influence of the PM2.5 mass burden on visibility was
very weak when its value was larger than 100 μg m−3. Only when the
mass burden of PM2.5 decreased to a certain threshold interval did the
visibility increase rapidly. This indicates that, when emission reduction
measures are taken to control haze occurrence, the mass burden of PM2.5
must be cut to below this threshold interval. The relationship between the
threshold of haze occurrence and the relative humidity in Beijing was fitted
by an exponential function, and the resulting fitting curves could provide a
new theoretical basis to understand and control haze formation in Beijing. |
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