___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 1 CMAQ Basics l Definitions & Acronyms l CMAQ Basics l CMAQ Modules l CMAQ Scripts

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 2 Definitions & Acronyms l SMOKE: Sparse Matrix Operator Kernel Emission processing system l CCTM: CMAQ Chemical Transport Model l BCON: Boundary Conditions processor l ICON: Initial Conditions processor l JPROC: Photolysis rates processor l MCIP: Meteorology Chemistry Interface Processor l CB-IV: Carbon Bond version 4 chemical mechanism

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 3 CMAQ Basics l CMAQ designed under the community modeling paradigm: – Modular – Multiscale – One-atmosphere – Portable – Accessible l Can model from urban (few km) to regional (hundreds of kilometers) to inter-continental (thousands of kilometers) scales of transport l Tropospheric O 3, acid deposition, visibility, particulate matter, toxics, mercury l Requires inputs from emissions and meteorology models, initial and boundary conditions l CMAQ = Chemical Transport Model + preprocessors

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 4 Atmospheric Diffusion Equation (ADE) l ADE* represents mass balance in which emissions, transport, diffusion, chemical reaction and removal processes are represented by: * Several assumptions included above

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 5 ADE (..Contd.) where, l i = chemical species, i (where i = 1, 2, … N ) l C i = pollutant concentration of species, i l u, v, w = horizontal and vertical wind speed components = f (x, y, z, t ) l K H, K V = horizontal and vertical turbulent diffusion coefficients = f (x, y, z, t ) l R i = rate of formation of i by chemical reactions = f ( C 1, C 2,.., C i,.. C N ) l S = emission rate of all precursors l L i = net rate of removal of pollutant i by surface uptake processes = f (x, y, z, t )

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 6 3-D Box Representation

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 7 Numerical Solution of Partial Differential Equations (PDEs) l E.g. Model Application with 100 Columns X 100 Rows X 25 Layers = 250,000 grid-cells l CB-IV Chemical Mechanism with 79 species and 94 reactions l Number of differential equations to be solved simultaneously per model output time step = 250,000 X 79 = 19,750,000 l For 1 day, # ODEs = X 24 = 474 million l For 1 month, # ODEs = X 24 X 30 = billion l For 1 year, # ODEs = X 24 X 365 = 173 billion

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 8 CMAQ Modules l ICON l BCON l JPROC l MCIP l CCTM

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 9 CMAQ Modules – ICON (1) l ICON is the CMAQ initial conditions preprocessor l Generates IC’s from: – Text-based vertical profiles – netCDF CTM output l Grid windowing l Default and custom mechanism conversion l Creates netCDF IC output file l Example text-based input file:

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 10 CMAQ Modules – ICON (2) Optional initial condition: The vertical coordinate of the model to generate these i.c. is the terrain-following sigma coordinate. The number of sigma layers and defined sigma levels are listed below "SO2 " 0.300E E E E E E-04 "SULF " 1.000E E E E E E-30 "NO2 " 0.167E E E E E E+00 "NO " 0.083E E E E E E+00 "O3 " 0.350E E E E E E-01

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 11 CMAQ Modules – BCON (1) l BCON is the CMAQ boundary conditions preprocessor l Generates BC’s from: – Text-based vertical profiles – netCDF CTM output l Static and time-dependent BC’s l Grid windowing capabilities l Default and custom mechanism conversion l Creates netCDF BC output file l Example text-based input file:

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 12 CMAQ Modules – BCON (2) Optional boundary condition: The vertical coordinate of the model to generate these b.c. is the terrain-following sigma coordinate. The number of sigma layers and defined sigma levels are listed below North "SO2 " 0.300E E E E E E-04 "SULF " 1.000E E E E E E-30 "NO2 " 0.167E E E E E E+00 "NO " 0.083E E E E E E+00 "O3 " 0.350E E E E E E-01

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 13 CMAQ Modules – JPROC (1) l JPROC is the CMAQ photolysis rate preprocessor l Generates daily photolysis lookup tables from: – Tabulated molecular cross-section/quantum yield data as a function of wavelength l Creates ASCII PHOT output files l Example input file format: ACROLEIN FAC = E E E …

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 14 CMAQ Modules – JPROC (2) (yyyyddd) Julian Date for the file 7 LEVELS (m) LATITUDES (deg) HOUR ANGLES (from noon) PHOTOLYTIC REACTIONS 'NO2_CBIV88 ', E E E E E E E E E+00

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 15 CMAQ Modules – MCIP l MCIP is the CMAQ meteorology preprocessor l Generates gridded 3-d and 2-d netCDF met inputs l Source data are MM5 binary MMOUT files or WRF netCDF files l MCIP has the option to recalculate some met variables (PBL, radiation fields) or use the MM5 predictions l MCIP3 optionally reads MM5 TERRAIN files for calculation of land-use based K v in CMAQ l MCIP outputs can also be used with SMOKE for emissions modeling

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 16 CMAQ Modules - CCTM l The CCTM is an Eulerian air quality model l Configuration options for CCTM science modules determined at compilation l Dynamic horizontal grid allocation and vertical layer structure determined at execution l Basic outputs include hourly concentrations for gaseous and aerosol pollutants, wet deposition, and dry deposition l Advanced outputs include Plume in Grid files and process analysis outputs

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 17 CCTM Science Process Modules l DRIVER → controls model data flows l HADV → horizontal advection l VADV → vertical advection l ADJCON → adjusts mixing ratios of pollutants l HDIFF → horizontal diffusion l VDIFF → vertical diffusion and deposition l CHEM → gas-phase chemistry l CLOUD → aqueous-phase chemistry, cloud-mixing l AERO → aerosol dynamics and size distributions l PING → plume-in-grid processes →

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 18 CCTM Science Process Classes l PHOT → computes photolysis rates l AERO-DEPV → computes particle size-dependent dry deposition velocities l UTIL → collection of utility subroutines

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 19 CMAQ Scripts l Build scripts and Makefiles l Run scripts

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 20 CMAQ Build Scripts (1) l The CMAQ system contains both C and FORTRAN programs – All of the CMAQ modules are FORTRAN programs – The compiler utility m3bld is a C program l m3bld is used for configuration management and compilation in the CMAQ system l m3bld must be compiled before use l Each CMAQ module has a build script associated with it that calls m3bld (MCIP uses a Makefile)

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 21 CMAQ Build Scripts (2) l Operating system dependencies are handled by the m3bld scripts l Configuration and compiler options are set in scripts that call m3bld l The build scripts use the configuration information to manage the Concurrent Version System (CVS) code repository l The build scripts provide the option of either generating executables or creating Makefiles

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 22 Makefiles l Alternative to build scripts for compiling executables l Require that the source code is online, i.e. no CVS options built into the script l Operating system dependencies l MCIP is the only CMAQ module that is currently distributed with only a Makefile option for compilation

___________________________________________________________________________CMAQ Basics ___________________________________________________Community Modeling and Analysis System 23 Run Scripts l User interface for CMAQ l CMAQ run scripts are C-shell files that set necessary environment variables, directory and file locations, and call executables l Episode settings defined in the CMAQ run scripts include: – Input and output file nomenclature – Horizontal grid definitions – 3-d meteorology file for setting vertical layer structure – Start date, start time, time step, and run duration – Logfile options – Debug options