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| Titel |
A new indicator on the impact of large-scale circulation on wintertime particulate matter pollution over China |
| VerfasserIn |
B. Jia, Y. Wang, Y. Yao, Y. Xie |
| 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. 20 ; Nr. 15, no. 20 (2015-10-27), S.11919-11929 |
| Datensatznummer |
250120123
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| Publikation (Nr.) |
 copernicus.org/acp-15-11919-2015.pdf |
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| Zusammenfassung |
| Extreme particulate matter (PM) air pollution of January 2013 in China was
found to be associated with an anomalous eastward extension of the Siberian
High (SH). We developed a Siberian High position index (SHPI), which depicts
the mean longitudinal position of the SH, as a new indicator of the
large-scale circulation pattern that controls wintertime air quality in
China. This SHPI explains 58 % (correlation coefficient of 0.76) of the
interannual variability of wintertime aerosol optical depth (AOD) retrieved
by MODIS over North China (NC) during 2001–2013. By contrast, the
intensity-based conventional Siberian High index (SHI) shows essentially no
skill in predicting this AOD variability. On the monthly scale, some
high-AOD months for NC are accompanied with extremely high SHPIs; notably,
extreme PM pollution of January 2013 can be explained by the SHPI value
exceeding 2.6 times the standard deviation of the 2001–2013 January mean.
When the SH extends eastward, thus higher SHPI, prevailing northwesterly
winds over NC are suppressed not only in the lower troposphere but also in
the middle troposphere, leading to reduced southward transport of pollution
from NC to South China (SC). The SHPI hence exhibits a significantly
negative correlation of −0.82 with MODIS AOD over SC during 2001–2013,
although the robustness of this correlation depends on that of
satellite-derived AOD. The suppressed northwesterly winds during high-SHPI
winters also lead to increased relative humidity (RH) over NC. Both the wind
and RH changes are responsible for enhanced PM pollution over NC during the
high-SHPI winters. |
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