Prediction of Air Quality

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Prediction of Air Quality over Tokyo Metropolitan
Area by Using the JCAP II Air Quality Simulation
System
Satoru Chatani1, Tazuko Morikawa1, Midori
Ashizaki1, Hideki Tashiro1, Hitoshi Kunimi1,
Hiroshi Hirai2 and Satoshi Yamazaki3 1. Japan
Petroleum Energy Center, Minato-ku, Tokyo,
JAPAN 2. Japan Automobile Research Institute,
Tsukuba, Ibaraki, JAPAN 3. Toyota Central RD
Labs., Inc., Nagakute, Aichi, JAPAN
Presented at the 6th Annual CMAS Conference,
Chapel Hill, NC, October 1-3, 2007
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What is JCAP? (Japan Clean Air Program)
Petroleum industry
Automobile industry
Joint research project (Japanese version of the
Auto-Oil program) to improve air quality
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Objectives of Air Quality Studies in JCAP II
(2002.4 - 2007.3)

• Develop the air quality modeling system and data
• - Simulate multi-scale air quality
• (from Asia to roadside)
• - Reflect real-world driving conditions
• - Contribute to the policymaking
• - Open to the public (de facto standard in Japan)

Analyses using the system were report to the
policymaking process.
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Structure of the Modeling System
Secondary organic aerosol model
Emission inventory except for vehicles
Macro-scale vehicle emission inventory model
Multiscale air quality model
Macro-scale traffic flow model
Air pollution including nano-particles for
roadside to urban / regional area Evaluation of
contribution from vehicles
Meteorological model
Micro-scale vehicle emission inventory model
Roadside air quality model
Micro-scale traffic flow model
Aerosol dynamic model
Measurement of aerosol characteristics
Details of our system is presented at the poster
session in tomorrow evening !!
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Current Status of NO2 in Japan
(Polluted area specified by the automobile NOx-PM
law)
Average conc. (ppb)
NAAQS Attainment
Some roadside stations still exceed NAAQS of NO2.
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Current Status of SPM in Japan
(SPM Suspended Particulate Matter, equivalent
to PM7) (Polluted area specified by the
automobile NOx-PM law)
Average conc. (mg/m3)
NAAQS Attainment
NAAQS attainment varies (partly due to Asian
dust).
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Application of the Modeling System
Emission inventory (Japan) Vehicle JCAP
II Other sources EAGrid-2000 (Kannari,
2007) (Outside Japan) REAS (Ohara, 2007), GEIA
(Granier, 2005)
Air quality model CMAQ v4.6
Meteorological model RAMS v4.4
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Target Domains of the Simulation
Main target area(Tokyo and surrounding area)
1,024km
176km
7,296km
7,296km
1,088km
160km
Asia Mesh 64 x 64 km
Japan G1 Mesh 16 x 16 km
Japan G2 Mesh 4 x 4 km
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Estimation of Vehicle Emissions
JCAP II Urban Motor Vehicle Emission Inventory
Model Emission processes Running, Cold-start,
Evaporative (Running loss, Hot soak loss,
Diurnal breathing loss), Road dust and Tire
wear Pollutants CO, NOx, SO2, THC, SPM, SO42-,
NH3
lt Basic equation (Running) gt
Category, model year, speed, mesh and hour
Emission Emission Factor Traffic Amount
Category, model year, speed, deterioration, temper
ature and humidity
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Traffic Amounts in Meshes
Census data (by Government)
No. Length Traffic
1 1.0 10,000
2 0.5 3,000

10 x 10 km (Whole Japan) 1x1 km (Around Tokyo)
Matching
Gridding by GIS
Traffic amount in meshes
Digital Road Map (DRM)
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RSD for Identifying High-emitters
Real-world emission measurement by RSD (Remote
Sensing Devices)
Average conc. and distribution (NO, PC)
Ratio of High-emitters was calculated and used
for estimation.
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Distribution of Pollutant Emissions
(Whole Japan, NOx in December)
Vehicles
Other Anthropogenic
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Distribution of Pollutant Emissions
(Around Tokyo, NOx in December)
Vehicles
Other Anthropogenic
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Simulation Cases
Target period of the simulation Nov. 1st to
Dec. 10th, 1999
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Estimated NOx Emissions
(Summed over the target area)
Vehicles
All Sources
Emission is largely reduced by replacement. Exclud
ing High-emitters are effective than new
regulations.
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Estimated SPM Emissions
(Summed over the target area)
Vehicles
All Sources
Road dust and tire wear become major SPM
sources. New regulations have negligible effects.
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Simulated NO2 Distribution
Observation
Simulation
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Simulated SPM Distribution
Observation
Simulation
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Time Series of Concentrations
(At stations within Tokyo metropolitan area)
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Performance of NO2 Simulation
MNE Mean Normalized Error MNB Mean Normalized
Bias
MNE
MNB gt 0
MNB lt 0
Average within the target area MNB -17.9, MNE
21.1
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Performance of SPM Simulation
MNE Mean Normalized Error MNB Mean Normalized
Bias
MNE
MNB gt 0
MNB lt 0
Average within the target area MNB -51.4, MNE
53.3
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Predicted Pollutant Concentrations
(Dec. 10th, 1999, Averaged over the target area)
NO2
SPM
Reduction of concentration is smaller than
emission. Why?
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Predicted Concentration of PM Components
(Dec. 10th, 1999, Averaged over the target area)
Secondary components
Changes in vehicle emissions influence on primary
components. Secondary components are affected by
transboundary transport.
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NOx Emission and Pollutant Concentrations
NOx
NO2
O3
NO2 is partly limited by O3 within the
metropolitan area. O3 may increase when NOx
emissions are reduced. O3, and NO2 are affected
by transboundary transport.
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Summary
Following future directions toward improving air
quality in Tokyo metropolitan area were implied
Additional regulations on new vehicles may
not be effective. High-emitters running in the
real-world should be eliminated. Reduction of
NOx emissions may cause increase of O3. Overall
strategies including NMVOC are necessary. Most
of SPM emission would be consisted of road dust
and sources except for vehicles. Strategies on
the transboundary transport are necessary from
the viewpoint of urban NO2 as well as O3 and PM.
Developed JCAP II system is feasible for various
analyses.
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Acknowledgement
This study was done in Japan Clean Air Program
(JCAP) II. JCAP II was conducted by Japan
Petroleum Energy Center and supported by the
Ministry of Economy, Trade and Industry, Japan.
Thank you!