CMAQ APPLICATION TO OZONE POLLUTION IN THE PEARL RIVER DELTA OF CHINA

1
CMAQ APPLICATION TO OZONE POLLUTION IN THE PEARL
RIVER DELTA OF CHINA

• Wei Zhou1,2 ,Yuanghang Zhang1,Xuesong
  Wang1,Daniel Cohan2
• 1.College of Environmental Science and
  Engineering, Peking University, Beijing,China
• 2.Department of Civil and Environmental
  Engineering, Rice University, Houston, TX
• Presented at the
• Sixth Annual CMAS Conference, October 1-3, 2007,
  Chapel Hill, NC

2
Overview

• Ozone pollution in the Pearl River Delta (PRD)
• Emission and land-sea breeze in PRD
• CMAQ modeling for October 2004
• Ozone distribution and transport in Pearl River
  Estuary (PRE)
• Process Analysis (PA) of Ozone formation in PRE

3
Ozone Pollution in PRD

• NAAQS-O3 200ug/m3 (93ppb)-1hr
• PRIDE_PRD October, 2004
• Max O3 concentration 178ppb at Donghu
• Hot spot - Southwest of PRD and PRE
• At most sites, max O3 concentrations were higher
  than NAAQS

Background wind
A Guangzhou
Guangzhou
Xinken
B Xinken
Donghu
C Donghu
The monitoring sites in the Program Regional
Integrated Experiments of Air Quality over Pearl
River Delta (PRIDE_PRD), October 2004
4
Configuration of Model-3/CMAQ

• CMAQ three nesting domains, 36km-12km-4km, v4.5,
  SAPRC-99, 13 vertical Layers, modeling period17
  23 October, 2004
• MM5 three modeling domains, 34 sigma levels
• Emission data domain1 TRACE-P emission
  inventory 2000, domain2 domain3Hong Kong EPD
  2001

5
Emission of NOx and VOC in PRD
VOC Emission at 1400, October 17
NOx Emission at 1400, October 17
The urban areas of Guangzhou, Shenzhen and Hong
Kong are the main origins of NOx and VOC emission
6
CMAQ modeling -ozone simulation vs measurement
Guangzhou (Urban site)
Xinken (Rural site)
Donghu (Downwind site)
7
Regional ozone distribution in PRD

• Downwind of Guangzhou ozone pollution hot spot
• Pearl River Estuary high ozone concentration
• Metropolitan area relatively low ozone
  concentration

Guangzhou
B
A
At 1400, October 17 2004 Plot the vertical
ozone profiles along lines A and B
8
Vertical ozone profiles over PRE
Ozone profile along Line B (latitudinal transect)
Ozone profile along Line A ( longitudinal
transect )
The black square is Xinken
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What drives the vertical distribution and high
concentration of ozone over PRE ?

• No direct large emission sources of VOC and NOx
• What about the meteorological field over PRE
  strong air circulations and land-sea breeze
• Can the land-sea breeze influence the ozone
  transport over PRE?

10
Land-sea breeze development in PRD
800, October 17
2000, 17 October
1000, October 17
1400, 17 October
11
Vertical structure of land-sea breeze
latitudinal transect
Sigma level

• Air circulation existed over PRE latitudinal
  transect
• At both banks of PRE, the horizontal wind speed
  is low, the vertical wind is relatively strong
• The height of the air circulation is
  approximately 600m
• (Red square is Xinken)

12
Vertical structure of land-sea breeze
longitudinal transect
Sigma level

• Air circulation existed over PRE, along the
  longitude
• The height of the air circulation is
  approximately 600m
• Air circulation will greatly affect air pollutant
  transport and accumulation
• (Red square is Xinken)

13
Process analysis of ozone formation at Xinken

• Vertical diffusion and vertical advection the
  principle contributors of ozone
• Horizontal advection the principle consumer of
  ozone

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Conclusion

• Heavy NOx and VOC are emitted in Guangzhou,
  Shenzhen and Hong Kong
• A severe regional ozone episode in October 2004
  is well reproduced by MM5 and CMAQ
• Regional high ozone concentration was located in
  downwind of Guangzhou and PRE the urban areas of
  Guangzhou had a relatively lower ozone
  concentration
• Analysis of the air circulation and ozone
  profiles indicates that the land-sea breeze had
  the greatest influence on ozone concentrations in
  PRE
• Acknowledgement We thank Dr. Yongtao Hu for
  setting up the coarse domain modeling of this
  study.