Surface O 3 over Beijing: Constraints from New Surface Observations. Yuxuan Wang, Mike B. McElroy, J. William Munger School of Engineering and Applied Sciences, Harvard University Jiming Hao, Hong Ma, Yaosheng Chen Tsinghua University, Beijing, China. GC 3 rd Users Meeting, April 15, 2007. - PowerPoint PPT Presentation
1 Surface O 3 over Beijing: Constraints from New Surface Observations Yuxuan Wang, Mike B. McElroy, J. William Yuxuan Wang, Mike B. McElroy, J. William Munger Munger School of Engineering and Applied Sciences, Harvard University School of Engineering and Applied Sciences, Harvard University Jiming Hao, Hong Ma, Yaosheng Chen Jiming Hao, Hong Ma, Yaosheng Chen Tsinghua University, Beijing, China Tsinghua University, Beijing, China GC 3 rd Users Meeting, April 15, 2007
Transcript
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Surface O3 over Beijing: Constraints from New Surface Observations
Yuxuan Wang, Mike B. McElroy, J. William MungerYuxuan Wang, Mike B. McElroy, J. William MungerSchool of Engineering and Applied Sciences, Harvard UniversitySchool of Engineering and Applied Sciences, Harvard University
Jiming Hao, Hong Ma, Yaosheng ChenJiming Hao, Hong Ma, Yaosheng Chen Tsinghua University, Beijing, ChinaTsinghua University, Beijing, China
1.1. Established by the China Project; started Established by the China Project; started in Nov 2004, continuously to datein Nov 2004, continuously to date
2.2. Miyun (Miyun (40.3N, 116.8E40.3N, 116.8E): Location chosen to ): Location chosen to observe both clean continental air and observe both clean continental air and pollution in the Beijng plumepollution in the Beijng plume
3.3. Directly observe trace-gas covariances Directly observe trace-gas covariances near the source; near the source;
4.4. Species measured: CO, OSpecies measured: CO, O33, CO, CO2 2 ((NONOxx, , NONOyy, SO, SO22))
5.5. Data used here: 30-min averages Data used here: 30-min averages prepared by J.W. Mungerprepared by J.W. Munger
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Sometimes It’s Clear
Courtesy of Bill Munger
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Mean Flow Patterns at the surface
East Asian Monsoon
Jan July
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Seasonal variations of other factors
Qiu et al., Atmos. Environ., 2000
Beijing AOD (1984-1994)
AOD
Model sulfate AOD peaks in July (0.5)
Precipitation
obs
model
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O3 observations: monthly statistics
• distributions of O3 skewed toward high values in summer months
• O3 peak in early summer and early fall
• Summertime ozone pollution
daytimedaytime O3
80ppbv
Legend
variations in summer
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Seasonality of Ozone at Lin An
Wang et al., 2002
obs: daytime mean (1999-2000)
model
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CO observations : monthly statistics
• small seasonality in CO• distributions of CO close to bimodal: clean continental air clean continental air and local pollutionand local pollution
Legenddaytime CO
variations in summer
>3ppm CO!
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GEOS-Chem Model Set-up
GEOS-4 global simulation; 2GEOS-4 global simulation; 2o o x 2.5x 2.5oo resolution; version 7-04-09resolution; version 7-04-09
Updated Chinese emissions of CO and Updated Chinese emissions of CO and NONOxx with monthly variability with monthly variability
Simulation period: Nov 2004 – Dec Simulation period: Nov 2004 – Dec 2006. Focus on 20062006. Focus on 2006
1-hr model outputs sampled by 1-hr model outputs sampled by observations. observations.
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Chinese emissions of CO and NOx
NOx (2004) CO (2001)
Zhang, Streets, et al., 2007
China total: 17.8 TgNO2 (up from 11.3 for TRACE-P)
Streets, et al., 2006
China total: 146 Tg/yr (up from 100)
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Monthly variations in Chinese emissions
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.180
0.200
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
All SourcesPowerIndustryHeating & Residential
NOx
(1.3: 1)
Zhang, Streets, et al., 2007
CO (1.5:1)
heating and residential
Seasonality not yet in the standard model
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Soil NOx emissions
Wang et al., 2007
a priori soil
a posteriori soil
• derived from 3-year GOME observations over east China • a posteriori 0.85 TgN/yr vs a priori 0.24 TgN/yr• peak in summer, significant in spring and fall
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Simulated Seasonal Variations (O3)
• model captures the overall seasonal patterns
• model fails to simulate the decrease of O3 in July
• model cannot reproduce very high ozone levels
Afternoon
model
model high bias in
summer
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Simulated Seasonal Variations (CO)
• model tends to underestimate mean CO concentrations• model captures the overall seasonal patterns
model
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CO-O3 relationship
Parrish et al., 1998
Miyun
• O3/CO ratio is much lower at Miyun
• seasonal variability are generally consistent between the two sites
Impact of precipitation and Impact of precipitation and cloudiness on local ozone cloudiness on local ozone production!production!
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Summary Observations reveal seasonal variations in OObservations reveal seasonal variations in O3, 3, CO, CO,
and their correlations in north China regionand their correlations in north China region
Model capture the general characteristics in Model capture the general characteristics in observations of CO and Oobservations of CO and O33
Major discrepancies in the modelMajor discrepancies in the model: : Underestimate CO concentrationsUnderestimate CO concentrations Not able to represent small-scale dynamics (in Not able to represent small-scale dynamics (in
transition seasons)transition seasons) Not able to capture low-ozone events in July, likely Not able to capture low-ozone events in July, likely
due to underestimate of cloudinessdue to underestimate of cloudiness still work in progress….still work in progress….
Need for a finer-resolution model -- nested-grid Need for a finer-resolution model -- nested-grid capability in GEOS-5capability in GEOS-5
