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| Titel |
Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence |
| VerfasserIn |
X. Y. Zheng, Y. F. Fu, Y. J. Yang, G. S. 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 ; 15, no. 21 ; Nr. 15, no. 21 (2015-11-02), S.12115-12138 |
| Datensatznummer |
250120134
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| Publikation (Nr.) |
 copernicus.org/acp-15-12115-2015.pdf |
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| Zusammenfassung |
| Regional heavy pollution events in eastern China (110–122° E,
28–40° N) are causing serious environmental problems. In this
study, the relationship between the degree of regional pollution and the
patterns of large-scale atmospheric circulation over eastern China in October
is investigated using 10-year (2001–2010) Terra/MODIS aerosol optical depth
and NCEP reanalysis data by both case study and composite analysis. Eighteen
polluted and 10 clean episodes are selected and categorised into six
polluted types and three clean types respectively. Generally speaking,
weather patterns such as a uniform surface pressure field in eastern China or a
steady straight westerly in the middle troposphere, particularly when being
at the rear of the anticyclone at 850 hPa, are typically responsible for heavy
pollution events. Meanwhile, clean episodes occur when strong southeastward
cold air advection prevails below the middle troposphere or air masses are
transported from sea to land. Uniform descending motion prevails over the
study region, trapping pollutants in the lower atmosphere. Therefore, the
value of vertical velocity averaged from 1000 to 100 hPa and divergence of
wind field in the lower troposphere are used in this study to quantify the
diffusion conditions in each circulation type. The results reveal that it is
often a clean episode when both the mean downward motion (larger than 2.56 × 10−2 Pa s−1) and the divergence
of low-level winds (larger than 1.79 × 10−2 s−1) are strong. Otherwise, it
is more likely to be a polluted episode. |
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