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| Titel |
Mesoscale modelling study of the interactions between aerosols and PBL meteorology during a haze episode in China Jing–Jin–Ji and its near surrounding region – Part 2: Aerosols' radiative feedback effects |
| VerfasserIn |
H. Wang, G. Y. Shi, X. Y. Zhang, S. L. Gong, S. C. Tan, B. Chen, H. Z. Che, T. Li |
| 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. 6 ; Nr. 15, no. 6 (2015-03-23), S.3277-3287 |
| Datensatznummer |
250119572
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| Publikation (Nr.) |
 copernicus.org/acp-15-3277-2015.pdf |
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| Zusammenfassung |
| Two model experiments, namely a control (CTL) experiment without
aerosol–radiation feedbacks and a experiment with online aerosol–radiation
(RAD) interactions, were designed to study the radiative feedback on regional
radiation budgets, planetary boundary layer (PBL) meteorology and haze formation due to aerosols during
haze episodes over Jing–Jin–Ji, China, and its near surroundings (3JNS
region of China: Beijing, Tianjin, Hebei, East Shanxi, West Shandong and North Henan) with a two-way atmospheric chemical
transport model. The impact of aerosols on solar radiation reaching Earth's
surface, outgoing long-wave emission at the top of the atmosphere, air
temperature, PBL turbulence diffusion, PBL height, wind speeds, air pressure
pattern and PM2.5 has been studied focusing on a haze episode during the
period from 7 to 11 July 2008. The results show that the mean solar radiation
flux that reaches the ground decreases by about 15% in 3JNS
and 20 to 25%in the region with the highest aerosol optical depth during the haze
episode. The fact that aerosol cools the PBL atmosphere but warms the
atmosphere above it leads to a more stable atmospheric stratification over
the region, which causes a decrease in turbulence diffusion of about 52%
and a decrease in the PBL height of about 33%. This consequently forms a
positive feedback on the particle concentration within the PBL and the
surface as well as the haze formation. Additionally, aerosol direct radiative forcing
(DRF) increases PBL wind speed by about 9% and weakens
the subtropical high by about 14 hPa, which aids the collapse of haze
pollution and results in a negative feedback to the haze episode. The
synthetic impacts from the two opposite feedbacks result in about a 14%
increase in surface PM2.5. However, the persistence time of both high
PM2.5 and haze pollution is not affected by the aerosol DRF. On the
contrary over offshore China, aerosols heat the PBL atmosphere and cause
unstable atmospheric stratification, but the impact and its feedback on the
planetary boundary layer height, turbulence diffusion and wind is weak, with the exception of the evident impacts on the
subtropical high. |
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