Weimin Jiang, Helmut Roth, Steven C' Smyth

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Comparison of MAQM and CMAQ model science,
input/output files, and modelling results of a
test case

• Weimin Jiang, Helmut Roth, Steven C. Smyth

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Outline

• Why do air quality models need full and flexible
  process-level (PL) modularity ?
• Brief review of the Modular Air Quality Model
  (MAQM) architecture and software components
• MAQM v1 science vs. CMAQ v4.5
• MAQM v1 I/O files vs. CMAQ v4.5
• Preliminary performance evaluation of MAQM v1 vs.
  CMAQ v4.6
• Future work
• Acknowledgements

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Why AQM with PL modularity ?

• Challenging tasks facing all serious air quality
  modellers
• Implement, revise, and/or update complicated
  model science correctly, efficiently, and in a
  timely manner
• Understand linkages between model behaviour
  model science
• Compare and exchange model science and algorithms
  between models.
• Process-level modularity is crucial to fulfilling
  these challenging tasks.

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Why AQM with PL modularity ? (contd)

• Desirable/dreamed outcomes of PL modularity in
  air quality models
• Simple transparent structure
• Transferable code
• Well structured model science algorithms
• Localised errors bugs
• Flexible process analysis capability
• Potential feedbacks among meteorology, emissions,
  and air quality
• Broad participation of the community in model
  development and improvement
• Robust model science and policy applications

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MAQM v1software components

• 1 simple MAQM driver MAQM
• 5 global data modules
• Grid_Data, Gas_Data, Aero_Data, Met_Data,
  Const_Data
• 20 process modules all optional and replaceable
• Grid Init_met Init_gas
  Init_aero
• BConc_gas BConc_aero Emission
  Gas_chem
• Nucleation Condensation Inor_aero
  SOA
• Coagulation Advection Diffusion
  Cloud
• Ddep_gas Ddep_part Meteorology
  Output

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MAQM v1software components (contd)

• 3 new pre-processors optional depending on
  process modules used
• PROCCHEM, ICON_CONVERSION, BCON_CONVERSION
• 6 utility subroutines
• find_name, int2str, real2str, DgSgM2,
  valid_conc, PMx
• 3 CMAQ pre-processors are used directly
• MCIP, SMOKE, JPROC

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MAQM v1 science

• Mostly adopted/adapted from CMAQ v4.5 for now
• New additions to and major differences from CMAQ
• Units SI-emphasis in code flexible in output
• Aerosol species and modes all species in all
  models flexible
• PMx size-resolved particle quantities
• SOA and saprc99_ae4_aq_SVOC gas mechanism
• 10 lumped SVOCs recorded and tracked in both gas
  and aerosol phases
• Mode-merging not included in current version
• Emissions an independent process
• Advection optional CMAQ/PPM or simple upstream
  scheme
• Cloud resolved cloud with total convective
  non-convective precipitations
• Sea salt not included in current version

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MAQM v1 input files

• Grid, meteorology, emissions, photolysis rates
• fully compatible with CMAQ
• GRIDCRO2D, GRIDDOT2D, GRIDCRO3D
• METCRO3D, METDOT3D, METBDY3D,
  METCRO2D
• EMIS
• Jvalue.
• Initial and boundary conditions
• ASCII files allowing flexible cell-range-specific
  concentration setting
• from ICONC_CONVERSION, BCONC_CONVERSION or other
  sources.

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MAQM v1 output files

• Gaseous species concentrations
  GasConc_yyyyddd
• Modal aerosol quantities Aero_Conc_yyyyddd
• total and speciated mass, number, and surface
  area concentrations
• Dg, sg.
• Size-specific aerosol quantities PMx_yyyyddd
• total and speciated mass, number, and surface
  area concentrations
• default size cut-offs PM0.01, PM0.1, PM1,
  PM2.5, PM5, PM10
• size cut-offs can be changed by users.
• I/O API format user-selectable conventional or
  SI units.

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Preliminary MAQM vs. CMAQ evaluation

• 139 x 99 42 km cells
• 000 July 1
• 500 July 30, 2002
• MAQM v1
• CMAQ v4.6 PMx
• Same emissions
• Same GEM
• meteorology
• Slightly different IC BC.

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MAQM vs. CMAQO3 statistics
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MAQM vs. CMAQtemporal O3 patterns
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MAQM vs. CMAQspatial O3 distributions
Average hourly O3
Maximum hourly O3
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MAQM vs. CMAQPM2.5 statistics
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MAQM vs. CMAQtemporal PM2.5 patterns
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MAQM vs. CMAQspatial distribution ofaverage
hourly PM2.5
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MAQM vs. CMAQspatial distribution ofmaximum
hourly PM2.5
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Possible future work

• Almost endless possibilities, e.g.
• Module-by-module science investigation and
  improvement
• New and alternative process modules
• Revised meteorology and emission modules to use
  input files from alternative sources
• On-line meteorology and/or emission modules
• Possibilities air quality
  meteorology
• 
  emission
• Time- and location-varying boundary conditions
• Process impact/sensitivity analysis
• Upstream and downstream modules e.g., climate
  input, health impact, etc.
• ......

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Acknowledgements

• US EPA
• The CMAQ model
• Early ideas of AQM modularity
• Community modelling concept.
• All the organizations that contributed to the
  CMAQ code that we adapted/adopted.
• Environment Canada
• Emissions, GEM meteorology, and measurement data
• CMAS CMAQ distribution and support
• Dr. John Li contribution to MAQM code
  development

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