1. CMAQ APPLICATION TO OZONE POLLUTION IN THE PEARL RIVER DELTA OF CHINA Wei Zhou 1,2,Yuanghang Zhang 1,Xuesong Wang 1,Daniel Cohan 2 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-O 3 : 200ug/m 3 (93ppb)-1hr PRIDE_PRD: October, 2004 Max O 3 concentration :178ppb at Donghu Hot spot - Southwest of PRD and PRE At most sites, max O 3 concentrations were higher than NAAQS A: Guangzhou C: Donghu B: Xinken The monitoring sites in the Program Regional Integrated Experiments of Air Quality over Pearl River Delta (PRIDE_PRD), October 2004 Guangzhou Xinken Donghu Background wind

4. Configuration of Model-3/CMAQ CMAQ: three nesting domains, 36km-12km-4km, v4.5, SAPRC-99, 13 vertical Layers, modeling period:17 – 23 October, 2004 MM5: three modeling domains, 34 sigma levels Emission data : domain1: TRACE-P emission inventory 2000, domain2 & domain3:Hong Kong EPD 2001

5. Emission of NOx and VOC in PRD NOx Emission at 14:00, October 17 VOC Emission at 14:00, 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 A B At 14:00, October 17 2004 Plot the vertical ozone profiles along lines A and B Guangzhou

8. Vertical ozone profiles over PRE Ozone profile along Line A ( longitudinal transect ) Ozone profile along Line B (latitudinal transect) The black square is Xinken

9. 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 8:00, October 17 10:00, October 17 14:00, 17 October 20:00, 17 October

11. Vertical structure of land-sea breeze – latitudinal transect 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) Sigma level

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

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

14. 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.