Aerosol, chemistry, and photolysis configuration files

Note

You should not modify these files unless:

  1. You need to update aerosol optical properties (such as cross-sections) that are used to compute aerosol optical depth.

  2. You need to add or remove species for which photolysis rates will be computed.

  3. You need to modify the GEOS-Chem chemical mechanism.

Aerosol optics configuration files

The following files (stored in the ExtData/CHEM_INPUTS/AEROSOL_OPTICS/Aerosol_Optics directory tree) contain optical properties for several aerosol species. See the geoschem_config.yml file for the current file path specification.

File

Contains optical properties for …

brc.dat

Brown carbon optical properties

dust.dat

Mineral dust optical properties

org.dat

Organic carbon optical properties

so4.dat

Sulfate optical properties

soot.dat

Black carbon optical properties

ssa.dat

Accumulation-mode sea salt aerosol

ssc.dat

Coarse-mode sea salt aerosol

h2so4.dat

Sulfuric acid

The properties are provided at multiple wavelengths to be used in the online calculation of the aerosol optical depth diagnostics. Up to three wavelentghs can be selected in the Radiation Menu of input.geos. These properties are also used for in the RRTMG radiative transfer model (if enabled).

Chemical mechanism configuration files

GEOS-Chem Classic and GCHP simulations use source code generated by The Kinetic PreProcessor. If you need to update the default chemistry mechanism, you will need to do the following steps:

  1. Modify the relevant KPP configuration files (described below);

  2. Run KPP to generate updated solver source code;

  3. Recompile the GEOS-Chem source code to create a new executable;

  4. Run your simulation.

Chemical mechanism configuration files are located in these folders:

KPP/fullchem

Contains configuration files for the default “full-chemistry” mechanism (NOx + Ox + aerosols + Br + Cl + I).

  • fullchem.kpp: Main configuration file for the fullchem mechanism.

  • fullchem.eqn: List of species and reactions for the fullchem mechanism.

KPP/carbon

Contains configuration files for the carbon gases mechanism (CH4-CO2-CO-OCS):

  • carbon.kpp: Main configuration file for the carbon mechanism.

  • carbon.eqn: List of species and reactions for the carbon mechanism.

KPP/custom

Contains configuration files that you can edit if you need to create a custom mechanism. We recommend that you create the custom in this folder and leave KPP/fullchem and KPP/Hg untouched.

  • custom.kpp: Copy of fullchem.kpp

  • custom.eqn: Copy of fullchem.eqn.

KPP/Hg

Contains configuration files for the mercury chemistry mechanism:

  • Hg.kpp: Main configuration file for the Hg mechanism.

  • Hg.eqn: List of species and reactions for the Hg mechanism.

Please see the following references for more information about KPP:

  1. The KPP user manual (kpp.readthedocs.io)

  2. Supplemental Guide: Update chemical mechanisms with KPP

Photolysis configuration files

Configuration files containing photolysis parameters (such as quantum yields, cross sections, branching ratios, etc.) may be found in subdirectories of ExtData/CHEM_INPUTS/CLOUD-J/. See the geoschem_config.yml file for the current file path specifications.

At present, the mercury (Hg) simulation still uses the legacy FAST-JX photolysis scheme. Configuration files for FAST-JX may be found in the ExtData/CHEM_INPUTS/FAST-JX/ directory tree.