xuemei wang, ziwei chai dept. of environmental sciences, sun yat-sen university, china
DESCRIPTION
Impacts of Meteorological Conditions Modified by Urban Expansion on Surface Ozone over Yangtz River Delta and Pearl River Delta region, China. Xuemei Wang, Ziwei Chai Dept. of Environmental Sciences, Sun Yat-Sen University, China Fei Chen, Christine Wiedinmyer, Alex Guenther, Mukul Tewari - PowerPoint PPT PresentationTRANSCRIPT
Impacts of Meteorological Conditions Modified by Urban Expansion on Surface Ozone
over Yangtz River Delta and Pearl River Delta region, China
Xuemei Wang, Ziwei ChaiDept. of Environmental Sciences, Sun Yat-Sen University, China
Fei Chen, Christine Wiedinmyer, Alex Guenther, Mukul TewariNational Center for Atmospheric Research, Boulder, CO, USA
6th Annual CMAS Conference October 1st,2007
Outline
• Regional Air Quality IssuesRegional Air Quality Issues
• Meteorological conditions modified
by urban expansion
• Impacts of urban expansion on Impacts of urban expansion on
surface ozonesurface ozone
• Summary
Satellite View Alerts China to Soaring Pollution (GOME and SCIAMACHY)
(Richter et al., Nature, Sept 1, 2005)
NO2 (vertical column)
NO2 (1996 - 2004)
Yangtze River Delta/ Shanghai Region
(YRD)
Pearl River Delta Region (PRD)
2001 2002 2003 2004
Spring
Summer
Autumn
Winter
Atmospheric Opitcal Depth(AOD)
Rapid Urban Expansion in PRD and YRD, China
1993
1993
2002
2002
PRD Area = 41700 km2, Population: 1986~20million, 2005 > 45 million
YRD Area= 95225 km2, Population: 1986~30million, 2005 > 60 million
2004-6-30 2:57am
Consequences of rapid urbanization
more pronounced urban heat islands (UHI)
more surface emission in PRD
0. 0100. 0
200. 0300. 0400. 0
500. 0600. 0700. 0
800. 0900. 0
NOx SO2 VOC
Emis.(KTon/year)
1997 2003
Impacts of Meteorological Conditions
Urban heat islands reduce the strength of nocturnal land-breeze (return flow from land to sea), so air
pollutants tend to accumulate over land.
Lo, J.C.F., A.K.H. Lau, F. Chen,J.C.H. Fung, and K.K.M. Leung, 2007 (J. Appli. Meteorol. And Climate)
WRF-Chem 12-km Simulation and Configuration
WRF-CHEM model configuration
WSM 5-class microphysics Kain-Fritsch cumulus
Dudhia scheme short wave RRTM longwave radiation
Yonsei University (YSU) (PBL) Noah land surface scheme
Urban Canopy model (UCM) Fast-J radiation scheme
RADM2/SORGAM (gas+ aerosol)
Initial and Boundary conditions
1-degree FNL for meteorology 6-min resolution emission inventory
TRACE-P observation data for chemistry
Simulation March 2001
Topographical height (m)
Evaluation of WRF-Chem Met. Simulation
Compared with NCEP analysis data, WRF monthly averaged 2-m
temperature and wind direction have the same pattern,
but with higher wind speed in YRD
Evaluation of WRF-Chem Simulated
Concentration
Simulations from two WRF-Chem packages have similar trend
Urbanization Increases both Day- and Night-time 2-m Temperature
Simulation Urban - Simulation PRE-Urban averaged for March 2001
PRD has smaller increase of 2-m temperature than YRD
YRD
PRD
Urbanization Decreases both Day- and Night-time 10-m Wind Speed
PRD has larger decrease of 10-m wind speed than YRD, and daytime reduction in wind speed is larger than that for nighttime
Urbanization Decreases both Day- and Night-time 2-m Water Mixing Ratio
PRD has larger decrease of 2-m water mixing ratio than YRD, and daytime reduction in Q2 is larger than that for nighttime
Urbanization Increases both Day- and Night-time Boundary Layer Depth
PRD has smaller increase in PBL depth than YRD
Urbanization Increases Surface Ozone
Concentration
Urbanization increases surface ozone (more for nighttime) PRD has larger increase than YRD
Differences in 10-m wind and O3
between Urban and Pre-urban
Urbanization enhances the convergence, especially in the PRD. Daytime convergence is weaker than that for nighttime
Relative O3 change (ppbv) and relative 10-m wind difference
Daytime Nighttime
Summary • Impacts of urban expansion can modify surface and
PBL structures:– increase temperature and decrease wind speed – PBL depth increase more in the day time than that in the
night time.
• Comparing PRD and YRD (cities clusters with different urban distribution and located in different climate regimes), PRD has – smaller increase of 2-m temperature than YRD– larger decrease of 10-m wind speed than YRD– smaller increase of PBL depth than YRD– larger increase of surface ozone than YRD.– larger decrease of 2-m water mixing ratio than YRD
• Dynamic and thermal effects of urbanization all have impacts on surface ozone.
Thank you !