The program CHEMMECH generates mechanism include files for all chemical mechanism-dependent CMAQ programs. Using an ASCII mechanism definition file as input, a combination of the Fortran 77 program CHEMMECH and the Python script, include_generator.py, created by Chao-Jung Chien at UC-Riverside, creates all of the Fortran include files that define the gas-phase chemical mechanisms for the CMAQ programs.

To implement new mechanisms created by CHEMMECH in the CMAQ programs, manually move the output include files from CHEMMECH to the $M3MODEL/include/release/{NewMechanism} directory within the CMAQ installation directories, where “NewMechanism” corresponds to the name of the new mechanism created with CHEMMECH. To invoke this new mechanism, set the Mechanism variable in the build script for the applicable CMAQ program to the name of the mechanism directory that you created. For example, if you used CHEMMECH to create include files for a mechanism that you call cb4_2006, create a directory under $M3MODEL/include/release called cb4_2006, move the include files created by CHEMMECH to this directory, and compile the CMAQ programs for this new mechanism by setting the Mechanism variable within the build scripts to cb4_2006.