1.2. Overview of CMAQ System Components

1.2. Overview of CMAQ System Components
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1.2.1.
1.2.2.
1.2.3. Summary Descriptions of the Major CMAQ Programs

CMAQ is a suite of FORTRAN-90 programs that work in concert to estimate ozone, particulate matter (PM), toxic compounds throughout the troposphere as well as acidic deposition. The five main CMAQ programs are

The initial conditions preprocessor (ICON)
The boundary conditions preprocessor (BCON)
The clear-sky photolysis rate calculator (JPROC)
The Meteorology-Chemistry Interface Processor (MCIP)
The CMAQ Chemistry-Transport Model (CCTM)

Ancillary support programs distributed with CMAQ include

The code builder/manager (M3BLD)
The chemical mechanism compiler (CHEMMECH)
The process analysis preprocessor (PROCAN)
The plume dynamics model for plume-in-grid simulations (PDM)

This section describes the CMAQ system concept, followed by summaries describing each of the programs listed above.

All CMAQ source code except MCIP is distributed in a UNIX tar file as a Concurrent Versions System (CVS) (http://ximbiot.com/cvs/cvshome) source code management archive. CVS is an open source, network-transparent version control system for managing source code in a software development environment. CMAQ uses CVS to control access to the distributed source code by maintaining a protected version of the original source code and using copies of the code when building executables. CVS must be installed on the user's UNIX system before installing CMAQ.

When the distributed CMAQ tar file is unpacked, a CVS directory tree is installed on the user's machine that contains archived copies of the CMAQ code. The CMAQ program M3BLD controls the extraction of copies of CMAQ source code from CVS based on the configuration options specified by the user. After exporting the CMAQ source code from CVS, M3BLD then invokes a FORTRAN compiler to compile the CMAQ source code into FORTRAN object files and link them with the necessary precompiled libraries to create binary CMAQ executables. C and FORTRAN compilers must be installed on the user's UNIX system in order to create CMAQ executables.