phy
December 8, 2020, 4:27pm
1
Hi, all!
Thanks
HyeonYeong Park
There is some information here:
### CMAQ Chemical Mechanisms
The CMAQ modeling system accounts for chemistry in three phases: gas, aerosol, and cloud droplets. Available mechanisms include variations of three photochemistry schemes such as different representations of secondary organic aerosols, additional model species representing Hazardous Air Pollutants, inclusion of dimethyl sulfide chemistry or detailed isoprene chemistry. Please consult the release notes for changes to mechanisms available in a specific version of CMAQ.
Fortran modules and namelists define a chemical mechanisms for the CMAQ model. Subdirectories of the $CMAQ_MODEL/CCTM/src/MECHS directory contain the files for available mechanisms. The species and emission control namelists enable setting runtime options for a mechanism. Species namelists define names, molecular weights and atmospheric processes (e.g., transport, cloud chemistry, and deposition). The files also determine whether the species concentrations and deposition results are written to output files. Emission control namelists define the emission inputs for model species. Two Fortran modules, RXNS_DATA_MODULE.F90 and RXNS_FUNC_MODULE.F90, define photochemistry for a mechanism. The data module specifies reactions and parameters. The functions module initializes photochemistry and calculates reaction rates constants. Because model source code define photochemistry for a mechanism, an executable version of the CMAQ model has a fixed photochemistry.
To modify or change photochemistry, requires modifying or replacing the modules then recompiling. The approach may not work because data hardcoded within the photochemistry solver is not correct, _if using an Euler Backward Interative (EBI) solver_, or because data used to calculate photolysis rates is not complete.
### Using predefined chemical mechanisms
To select a predefined mechanism configuration in CMAQ, set the *Mechanism* variable in the build scripts to a one of the mechanism subdirectories located under $CMAQ_MODEL/CCTM/src/MECHS. The below table lists mechanisms available in this version of the CMAQ model.
Table 1. CMAQv5.3 Chemical Mechanisms
|**Mechanism Name** | **Photochemistry** | **Model Species<sup>1,2</sup>** | **Cloud Chemistry Module<sup>3</sup>** |
| ----------------- | ---------------------------------------------------- | -------------------- | ---------------------- |
| cb6r3_ae7_aq | [Carbon Bond 6 version r3 with aero7 treatment of SOA](mechanism_information/cb6r3_ae7_aq/mech_cb6r3_ae7_aq.md) | [species table 1](mechanism_information/cb6r3_ae7_aq/cb6r3_ae7_aq_species_table.md) | acm_ae7 |
| cb6r3_ae7_aqkmt2 | [Carbon Bond 6 version r3 with aero7 treatment of SOA](mechanism_information/cb6r3_ae7_aq/mech_cb6r3_ae7_aq.md) | [species table 1](mechanism_information/cb6r3_ae7_aq/cb6r3_ae7_aq_species_table.md) | acm_ae7_kmt2 |
| cb6r3m_ae7_kmtbr | [Carbon Bond 6 version r3 with aero7 treatment of SOA and DMS and marine halogen chemistry](mechanism_information/cb6r3m_ae7_kmtbr/mech_cb6r3m_ae7_kmtbr.md) | [species table 2](mechanism_information/cb6r3m_ae7_kmtbr/cb6r3m_ae7_kmtbr_species_table.md) | acm_ae7_kmtbr |
| cb6r3_ae6_aq | [Carbon Bond 6 version r3 with aero6 treatment of SOA](mechanism_information/cb6r3_ae6_aq/mech_cb6r3_ae6_aq.md) | [species table 3](mechanism_information/cb6r3_ae6_aq/cb6r3_ae6_aq_species_table.md) | acm_ae6 |
show original
and
phy
December 9, 2020, 3:22am
3
I’m really appreciate for your replying for my question
