|Mechanism Name||Pre-processor Code||Chemistry Specifier|
|TSMLT1||Troposphere, stratosphere, mesosphere, and lower thermosphere||231||583 (433 kinetic, 150 photolysis)||MZ197_TSMLT1_20180423||pp_waccm_tsmlt_mam4||??|
|TS1||Troposphere and stratosphere||221||528 (405 kinetic, 123 photolysis)||MZ198_TS1-simpleVBS_20180423||pp_trop_strat_mam4_vbs||trop_strat_mam4_vbs|
|MA||Middle atmosphere: stratosphere, mesosphere, and lower thermosphere||98||298 (207 kinetic, 91 photolysis)||pp_waccm_ma_mam4||??|
|MAD||Middle atmosphere plus D-region ion chemistry||135||593 (489 kinetic, 104 photolysis)||pp_waccm_mad_mam4||??|
|SC||Specified chemistry for WACCM||29||12 (11 kinetic, 1 photolysis)||pp_waccm_sc_mam4||??|
|CAM||Simplified chemistry for CAM to to allow tropospheric aerosol formation||32||7 (6 kinetic), 1 photolysis)||modal_aero||??|
IS THE CHEMICAL SPECIFIER THE SAME AS THE PRE-PROCESSOR CODE WITHOUT THE PP AS IS IN CAMCHEM DEFAULT
The input files and fortran routines for these default mechanisms are located in $CCSMROOT/components/cam/src/chemistry/ in the folder specified by the pre-processor code. The chemistry specifier refers to the chemistry (-chem) specified in "CAM_CONFIG_OPTS" in env_build.xml. For example (in bold), <entry id="CAM_CONFIG_OPTS" value="-phys cam6 -chem trop_strat_mam4_vbs -age_of_air_trcs -offline_dyn -nlev 32">. CAM- CAM-Chem and WACCM compsets are defined in section 4.4 and 4.5 of the CAM6 user guide https://ncar.github.io/CAM/doc/build/html/users_guide/atmospheric-configurations.html. All CAM-Chem compsets default to the TS1 chemical mechanism and WACCM compsets default to TSMLT1 chemical mechanism. The TS1 and TSMLT1 chemical mechanisms are described in Emmons et al., 2018 2019 (in preparation).
To review the chemistry used in a specific compset, build your case as described in Run CAM-Chem on Cheyenne. In the $CASEROOT/CaseDocs folder there are 2 files that describe the chemistry chem_mech.in and chem_mech.doc. Both have similar information describing the species and reaction rates. The chem_mech.doc file is in a more human readable format and includes the differential equations defining the production and loss terms of each species. The chem_mech.in file is the version read by the code, and the version you will alter to make changes to the chemical mechanism.