Understanding of regional air pollution over China using CMAQ, part II. Process analysis and sensitivity of ozone and particulate matter to precursor emissions

Following model evaluation in part I, this part II paper focuses on the process analysis and chemical regime analysis for the formation of ozone (O 3) and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM 10) in China. The process analysis results show that horizontal tran...

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Bibliographic Details
Published in:Atmospheric environment (1994) 2010-09, Vol.44 (30), p.3719-3727
Main Authors: Liu, Xiao-Huan, Zhang, Yang, Xing, Jia, Zhang, Qiang, Wang, Kai, Streets, David G., Jang, Carey, Wang, Wen-Xing, Hao, Ji-Ming
Format: Article
Language:English
Subjects:
Aircraft components
Applied sciences
Atmospheric pollution
China
Clouds
CMAQ
Emissions control
Exact sciences and technology
Horizontal
Indicators
Indicators for O 3 and PM 2.5 chemistry
Ozone
Pollution
Process analysis
Reduction
Seasons
Transport
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Summary:Following model evaluation in part I, this part II paper focuses on the process analysis and chemical regime analysis for the formation of ozone (O 3) and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM 10) in China. The process analysis results show that horizontal transport is the main contributor to the accumulation of O 3 in Jan., Apr., and Oct., and gas-phase chemistry and vertical transport contribute to the production and accumulation of O 3 in Jul. Removal pathways of O 3 include vertical and horizontal transport, gas-phase chemistry, and cloud processes, depending on locations and seasons. PM 10 is mainly produced by primary emissions and aerosol processes and removed by horizontal transport. Cloud processes could either decrease or increase PM 10 concentrations, depending on locations and seasons. Among all indicators examined, the ratio of P HNO 3 / P H 2 O 2 provides the most robust indicator for O 3 chemistry, indicating a VOC-limited O 3 chemistry over most of the eastern China in Jan., NO x-limited in Jul., and either VOC- or NO x-limited in Apr. and Oct. O 3 chemistry is NO x-limited in most central and western China and VOC-limited in major cities throughout the year. The adjusted gas ratio, AdjGR, indicates that PM formation in the eastern China is most sensitive to the emissions of SO 2 and may be more sensitive to emission reductions in NO x than in NH 3. These results are fairly consistent with the responses of O 3 and PM 2.5 to the reductions of their precursor emissions predicted from sensitivity simulations. A 50% reduction of NO x or AVOC emissions leads to a reduction of O 3 over the eastern China. Unlike the reduction of emissions of SO 2, NO x, and NH 3 that leads to a decrease in PM 10, a 50% reduction of AVOC emissions increases PM 10 levels. Such results indicate the complexity of O 3 and PM chemistry and a need for an integrated, region-specific emission control strategy with seasonal variations to effectively control both O 3 and PM 2.5 pollution in China.
ISSN:1352-2310
1873-2844
DOI:10.1016/j.atmosenv.2010.03.036