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| Titel |
Air quality forecast of PM10 in Beijing with Community Multi-scale Air Quality Modeling (CMAQ) system: emission and improvement |
| VerfasserIn |
Q. Z. Wu, W. S. Xu, A. J. Shi, Y. T. Li, X. J. Zhao, Z. F. Wang, J. X. Li, L. N. Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 5 ; Nr. 7, no. 5 (2014-10-02), S.2243-2259 |
| Datensatznummer |
250115731
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| Publikation (Nr.) |
 copernicus.org/gmd-7-2243-2014.pdf |
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| Zusammenfassung |
The MM5-SMOKE-CMAQ model system, which was developed by the United
States Environmental Protection Agency (US EPA) as the MODELS-3
system, has been used for daily air quality forecasts in the
Beijing Municipal Environmental Monitoring Center (Beijing MEMC), as
a part of the Ensemble air quality Modeling forecast System for
Beijing (EMS-Beijing) since the 2008 Olympic Games. According to
the daily forecast results for the entire duration of 2010, the model shows good
performance in the PM10 forecast on most days
but clearly underestimates PM10 concentration during some air pollution episodes. A typical
air pollution episode from 11–20 January 2010 was chosen,
in which the observed air pollution index of particulate matter
(PM10-API) reached 180 while the forecast
PM10-API was about 100.
In this study, three numerical methods are used for model improvement: first,
by enhancing the inner domain with 3 km resolution grids, and expanding the coverage from only Beijing to an area including Beijing and its surrounding
cities; second, by adding more regional point source emissions located
at Baoding, Landfang and Tangshan, to the south and east of
Beijing; third, by updating the area source emissions, including the
regional area source emissions in Baoding and Tangshan and the local
village/town-level area source emissions in Beijing.
The last two methods are combined as the updated emissions method. According
to the model sensitivity testing results by the CMAQ model, the updated
emissions
method and expanded model domain method can both improve the model
performance separately. But the expanded model domain method has better
ability to capture the peak values of PM10 than the updated emissions
method due to better reproduction of the pollution transport process in this episode.
As a result, the hindcast results ("New(CMAQ)"), which are driven by the
updated emissions in the expanded model domain, show a much better model
performance in the national standard station-averaged PM10-API. The
daily hindcast PM10-API reaches 180 and is much closer to
the observed value, and has a high correlation coefficient of 0.93. The
correlation coefficient of the PM10-API in all Beijing
MEMC stations between the hindcast and observation is 0.82,
clearly higher than the forecast 0.54. The FAC2 increases
from 56% in the forecast to 84% in the hindcast, and the
NMSE decreases from 0.886 to 0.196. The hindcast also has better model
performance in PM10 hourly concentrations during the typical air
pollution episode. The updated emissions method accompanied by a suitable domain in
this study improved the model performance for the Beijing area
significantly. |
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