As mentioned in comment 739, https://forum.cmascenter.org/session/email-login/dafe747ca68182af24a59287067de42e, the chemical mechanism is a build time option (not runtime option). The mechanism is compiled into the executable.
CHEMMECH is a utility that creates RXNS*F90 files (if you want to update the mechanism) which must be compiled in the executable. The default versions reside in the CMAQ/CCTM/src/MECHS folder.
If you want to change a mechanism, you should:
- Modify the mech*.def and GC/AE/NR*.nml as appropriate for your update. mech*.def is not actually used in creating the executable, but is an intermediate file from which information is extracted for fortran code.
- Run CHEMMECH to translate the mech*.def information into the two RXNS*.F90 files
- If you want to run the ebi solver within CMAQ, propagate the RXNS*.F90 information to hr*.F files (which normally reside in CMAQ/CCTM/src/gas/ebi*) via create_ebi
chemmech and create_ebi reside in the UTIL folder: https://github.com/USEPA/CMAQ/tree/5.3.b2/UTIL
I’m not sure of your specific problem. Do you have access to pgf90?