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| Titel |
Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog–haze event over the North China Plain |
| VerfasserIn |
Y. Gao, M. Zhang, Z. Liu, L. Wang, P. Wang, X. Xia, M. Tao, L. Zhu |
| 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. 8 ; Nr. 15, no. 8 (2015-04-24), S.4279-4295 |
| Datensatznummer |
250119665
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| Publikation (Nr.) |
 copernicus.org/acp-15-4279-2015.pdf |
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| Zusammenfassung |
| The feedback between aerosol and meteorological variables in the atmospheric
boundary layer over the North China Plain (NCP) is analyzed by conducting
numerical experiments with and without the aerosol direct and indirect
effects via a coupled meteorology and aerosol/chemistry model (WRF-Chem). The
numerical experiments are performed for the period of 2–26 January 2013, during
which a severe fog–haze event (10–15 January 2013) occurred, with the
simulated maximum hourly surface PM2.5 concentration of ~600 ug
m−3, minimum atmospheric visibility of ~0.3 km, and 10–100 hours
of simulated hourly surface PM2.5 concentration above 300 ug m−3
over NCP. A comparison of model results with aerosol feedback against
observations indicates that the model can reproduce the spatial and temporal
characteristics of temperature, relative humidity (RH), wind, surface
PM2.5 concentration, atmospheric visibility, and aerosol optical depth
reasonably well. Analysis of model results with and without aerosol feedback
shows that during the fog–haze event aerosols lead to a significant negative
radiative forcing of −20 to −140 W m−2 at the surface and a large
positive radiative forcing of 20–120 W m−2 in the atmosphere and
induce significant changes in meteorological variables with maximum changes
during 09:00–18:00 local time (LT) over urban Beijing and Tianjin and south
Hebei: the temperature decreases by 0.8–2.8 °C at the
surface and increases by 0.1–0.5 °C at around 925 hPa, while RH
increases by about 4–12% at the surface and decreases by 1–6% at
around 925 hPa. As a result, the aerosol-induced equivalent potential
temperature profile change shows that the atmosphere is much more stable and
thus the surface wind speed decreases by up to 0.3 m s−1 (10%)
and the atmosphere boundary layer height decreases by 40–200 m
(5–30%) during the daytime of this severe fog–haze event. Owing to this
more stable atmosphere during 09:00–18:00, 10–15~January, compared to the
surface PM2.5 concentration from the model results without aerosol
feedback, the average surface PM2.5 concentration increases by
10–50 μg m−3 (2–30%) over Beijing, Tianjin, and south
Hebei and the maximum increase of hourly surface PM2.5
concentration is around 50 (70%), 90 (60%), and
80 μg m−3 (40%) over Beijing, Tianjin, and south
Hebei, respectively. Although the aerosol concentration is maximum
at nighttime, the mechanism of feedback, by which meteorological variables
increase the aerosol concentration most, occurs during the daytime (around
10:00 and 16:00 LT). The results suggest that aerosol induces a more stable
atmosphere, which is favorable for the accumulation of air pollutants, and
thus contributes to the formation of fog–haze events. |
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