Advanced Computer Modelling of TrafficRelated Air Pollution

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Advanced Computer Modelling of Traffic-Related
Air Pollution

• Weimin Jiang

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Outline

• Introduction
• Target Pollutants Ozone and PM formation
  mechanisms
• 3-D AQM system overview
• CTM Modelling system 3-D grid Meteorology
  Emissions
• Emission input required by 3-D models
• Raw EI Data Spatial allocation Temporal
  allocation Chem. speciation
• Model evaluation and application
• Models output Evaluation using measurement data
  Concept of scenario and control strategy
  modelling
• Summary
• Animation Conclusion remarks

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Source A Primer on Ozone Depletion, Environment
Canada, 1993
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Photochemical Ozone Pollution in Canada
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Chemistry of Ground Level Ozone Formation
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Atmospheric Aerosol Processes
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CTMChemical-Transport Model

• Centre of a modelling system
• Emissions
• Gas-phase chemistry
• Aerosol processes
• Transport process advection, diffusion
• Deposition wet, dry
• Cloud process dynamics and chemistry
• e.g.
• CMAQ Community Multiscale Air Quality Model

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Air QualityModelling System
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Lower Fraser Valley
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Lower Fraser Valley
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3-D Grid
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MM5 Wind Field (m/s) at 1700 August 5
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MM5 Temperature Field (K),1700 August 5
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Emissions

• Raw emission inventory - Source categories
• Point
• Area
• Mobile
• Biogenic
• Emission inventory modelling and processing
• Temporal allocation
• Spatial allocation
• Chemical speciation

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Emissions
Sources
Processing
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Vehicle Emissions
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1995 NET Point Source File Start Field Type Le
ngth Description ---------------------------------
------------------ 1 STID Int 2 State
Code 3 CYID Int 3 County Code 6 PLANTID Char 15
Plant Identification Code 21 POINTID Char 15 Poin
t Identification Code 36 STACKID Char 12 Stack
Identification Code 48 ORISID Char 6 DOE Plant
ID 54 BLRID Char 5 Boiler Identification
Code 59 SEGMENT Char 2 DOE ID 61 PLANT Char 40 P
lant Name 101 SCC Char 10 Source Classification
Code 111 STKHGT Real 4.0 Stack Height
(ft) 115 STKDIAM Real 6.2 Stack Diameter
(ft) 121 STKTEMP Real 4.0 Stack Gas Exit
Temperature (deg F) 125 STKFLOW Real 10.2 Stack
Gas Flow Rate (ft3/min) 135 STKVEL Real 9.2 Stack
Gas Exit Velocity (ft/sec) 144 BOILCAP Real 8.2
Design Capacity (mmBtu/hr) 152 CAPUNITS Char 1 Ca
pacity Unit Code 153 WINTHRU Real 2.0 Winter
throughput ( of Annual) 155 SPRTHRU Real 2.0 Spr
ing throughput ( of Annual) 157 SUMTHRU Real 2.0
Summer throughput ( of Annual) 159 FALTHRU Real
2.0 Fall throughput ( of Annual) 161 HOURS Int
2 Normal Operating Time (hours/day) 163 START Int
2 Normal Operation Start Time 165 DAYS Int 1 Nor
mal Operating Time (days/week) 166 WEEKS Int 2 No
rmal Operating Time (weeks/year)
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1995 NET Area Source File Start Field Type Len
gth Description ----------------------------------
----------------- 1 STID Int 2 State
Code 3 CYID Int 3 County Code 6 SCC
Char 10 Source Classification
Code 16 VOC_ANN Real 10.4 VOC Annual Emissions
(short tons) 26 NOX_ANN Real 10.4 NOX Annual
Emissions (short tons) 36 CO_ANN Real 10.4 CO
Annual Emissions (short tons) 46 SO2_ANN Real 10.
4 SO2 Annual Emissions (short tons) 56 PM10_ANN R
eal 10.4 PM10 Annual Emissions (short
tons) 66 PM25_ANN Real 10.4 PM2.5 Annual
Emissions (short tons) 76 NH3_ANN Real 10.4 NH3
Annual Emissions (short tons) 86 VOC_OSD Real 10.
4 VOC Ozone Season Emissions (tons/day) 96 NOX_OSD
Real 10.4 NOX Ozone Season Emissions
(tons/day) 106 CO_OSD Real 10.4 CO Ozone Season
Emissions (tons/day) 116 SO2_OSD Real 10.4 SO2
Ozone Season Emissions (tons/day) 126 PM10_OSD Re
al 10.4 PM10 Ozone Season Emissions
(tons/day) 136 PM25_OSD Real 10.4 PM2.5 Ozone
Season Emissions (tons/day) 146 NH3_OSD Real 10.4
NH3 Ozone Season Emissions (tons/day) .
. .
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Motor Vehicle VMT File This format used for
both NET and MIDPRO format Mobile Source
files ASCII fixed-format Record Length 40
Characters Start Field Type Length Description --
----------------------------------------- 1 STID I
nt 2 State Code 3 CYID Int 3 County
Code 6 1 Not Used 7 SCC Char 10 AMS Source
Classification Code 17 1 Not Used 18 VMT Real 14
Vehicle Miles Travelled (106 mi/yr) 32 1 Not
Used 33 VTYPE Char 5 Vehicle Type 38 1 Not
Used 39 Int 2 Speed (mi/hr) Valid Vehicle
Types LDGV LDGT1 LDGT2 HDGV LDDV LDDT HDDV MC
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• Vehicle emission VMT x Emission Factor
• A mobile model. e.g., Mobile 6 ? Emission
  Factors for
• vehicle types, e.g., LDGV, LDGT1, HDDV, ...
• T
• Speed

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Temporal Allocation

• Source Light Duty Gasoline Vehicle on an
  Arterial Road
• SCC Monthly Profile
  Weekly Profile Diurnal Profile
• 2201001130 60
  2002 2002
• Monthly
• 60 72 72 80 80 80 96 96 96 85 85 85
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• Weekly
• 2002 101 100 100 109 111 94 89
• Diurnal
• 2002 80 50 40 46 70 200 433 600 554 541 560
  597 611 628
• 679 736 819 824 601 398 312 266 208 146

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Spatial Allocation

• Source Light Duty Gasoline Vehicles on a Rural
  Interstate
• SCC Profile
• 2201001110 50
• Profile County i j Ratio
• 50 41003 6 1 0.0013957896
• 50 41003 7 1 0.0140486259
• 50 41003 7 2 0.0029973561
• 50 41003 7 3 0.0038421813
• . . .
  . .
• . . .
  . .
• Total 1 for
  a county

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Integration of Canadian Emission Inventory into
Models-3Integrated Canada-US Road Network
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VOC Emissions
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Models-3/CMAQ Aerosol Species

• ASO4I ASO4J
• ANH4I ANH4J
• ANO3I ANO3J
• AORGAI AORGAJ
• AORGBI AORGBJ
• AORGPAI AORGPAJ
• AECI AECJ
• A25I A25J

• ACORS
• ASEAS
• ASOIL
• AH2OI, AH2OJ
• NUMATKN
• NUMACC
• NUMCOR

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Emitted Species
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Chemical Speciation

• Source LDGV exhaust in Can. Lower Mainland at
  42 mph
• SCC Spec.Prof. Species MassFrac ModelSpecies
• MV01270EXH 70097 propane 0.08870 ALK1
• isobutane 0.01266 ALK1
• . . .
• . . .
• benzene 0.04197 ARO1
• toluene 0.06079 ARO1
• . . .
• . . .
• Species are converted into model species
  through various lumping schemes

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Emissions
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BiogenicEmission Modelling

• Biogenic emission models e.g. BEIS-3
• Input to the models
• Temperature
• Wind speed
• Land use
• Date, time (sunlight intensity)
• Cloud cover
• Grid definition
• Output from the models
• Hourly emissions of biogenic model species, e.g.
• ISOP, TERP, OVOC, NO

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CMAQ Results O3 and PM2.5
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Model Evaluation O3 (7/31 - 8/7/93)
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Model Evaluation PM2.5
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s number of monitoring stations ni number
of observed concentrations in station i Co(i,
j) the j-th observed concentration in the i-th
station Ce(i, j) the j-th model estimated
concentration in the i-th station d number of
days si number of stations where peak observed
data is available on the i-th day
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Model Application What-If Scenarios

• What if gasoline is replaced by M85, E10 etc. ?

What if electrical vehicles are used ?
What if a regulation is developed and/or
implemented ?
What if a highway is built or widened ?
What if a new power plant is built in location A ?
. . .
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• Model application
• Impact of Alternative Fuels

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Preliminary CMAQ Results Animation

• 15 km domain O3 3-D concentration field
• 15 km domain PM2.5 15 mg/m3 isosurface and SO2
  emissions

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