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| Titel |
The distribution and trends of fog and haze in the North China Plain over the past 30 years |
| VerfasserIn |
G. Q. Fu, W. Y. Xu, R. F. Yang, J. B. Li, C. S. Zhao |
| 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. 21 ; Nr. 14, no. 21 (2014-11-13), S.11949-11958 |
| Datensatznummer |
250119158
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| Publikation (Nr.) |
 copernicus.org/acp-14-11949-2014.pdf |
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| Zusammenfassung |
| Frequent low visibility, haze and fog events were found in the North China
Plain (NCP). Data throughout the NCP during the past 30 years were examined
to determine the horizontal distribution and decadal trends of low
visibility, haze and fog events. The impact of meteorological factors such
as wind and relative humidity (RH) on those events was investigated. Results reveal distinct
distributions of haze and fog days, due to their different formation
mechanisms. Low visibility, haze and fog days all display increasing trends
of before 1995, a steady stage during the period 1995–2003 and a
drastically drop thereafter. All three events occurred most frequently
during the heating season. Benefiting from emission control measures, haze
and fog both show decreasing trends in winter during the past 3 decades,
while summertime haze displays continuous increasing trends. The
distribution of wind speed and wind direction as well as the topography
within the NCP has determinative impacts on the distribution of haze and
fog. Weakened south-easterly winds in the southern part of the NCP have
resulted in high pollutant concentrations and frequent haze events along the
foot of the Taihang Mountains. The orographically generated boundary layer
wind convergence line in the central area of the southern NCP is responsible
for the frequent fog events in this region. Wind speed has been decreasing
throughout the entire southern NCP, resulting in more stable atmospheric
conditions and weaker dispersion abilities, calling for harder efforts to
control emissions to prevent haze events. Haze events are strongly
influenced by the ambient RH. RH values associated with haze days are
evidently increasing, suggesting that an increasing fraction of haze events
are caused by the hygroscopic growth of aerosols, rather than simply by high
aerosol loadings. |
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