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, TXPresented at the

Sixth Annual CMAS Conference, October 1-3, 2007, Chapel Hill, NC

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

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

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

XinkenDonghu

Background wind

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

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

CMAQ modeling -ozone simulation vs measurement

Guangzhou (Urban site)

Xinken(Rural site)

Donghu (Downwind site)

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 2004Plot the vertical ozone profiles along lines A and B

Guangzhou

Vertical ozone profiles over PRE

Ozone profile along Line A( longitudinal transect )

Ozone profile along Line B(latitudinal transect)

The black square is Xinken

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?

Land-sea breeze development in PRD

8:00, October 17 10:00, October 1714:00, 17 October20:00, 17 October

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

• 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 transectSigma level

Process analysis of ozone formation at Xinken

• Vertical diffusion and vertical advection –the principle contributors of ozone

• Horizontal advection – the principle consumer of ozone

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 Acknowledgement : We thank Dr. Yongtao Hu for setting up the coarse domain modeling of this study.the coarse domain modeling of this study.