# Metadata

CRACMM workflows require that each species in CRACMM has a representative structure specified by a SMILES string. These structures are used to obtain metadata such as solubility (Henry's law coefficients), volatility, and other parameters.

## Species Information

- All files here are autogenerated by python code from CMAQ files (see the utilities folder). Each mechanism is documented in a markdown and csv file.
  * [CRACMM1](https://github.com/USEPA/CRACMM/tree/main/metadata/cracmm1) metadata: [online table version](cracmm1/cracmm1_aq_species_table.md) and [csv version](cracmm1/cracmm1_aq_metadata.csv)
  * [CRACMM1AMORE](https://github.com/USEPA/CRACMM/tree/main/metadata/cracmm1amore) metadata: [online table version](cracmm1amore/cracmm1amore_aq_species_table.md) and [csv version](cracmm1amore/cracmm1amore_aq_metadata.csv)
  * [CRACMM2](https://github.com/USEPA/CRACMM/tree/main/metadata/cracmm2) metadata: [online table version](cracmm2/cracmm2_species_table.md) and [csv version](cracmm2/cracmm2_metadata.csv)
- The metadata file in csv is the most complete for describing species and their properties in CMAQ. Properties include:
  * Species name
  * Description
  * Phase (G=gas, P=particle, GP=gas and particle)
  * Stable ("Yes" indicates species with sufficient lifetime to warrant transport in the host model)
  * Molecular weight (g/mol)
  * Representative (compound that best represents the species)
  * SMILES (for representative compound structure)
  * Henry's Law Coefficient for wet removal processes (M/atm)
  * Enthalpy of solvation used to adjust the Henry's Law Coefficient for temperature (K)
  * Density of species in the particulate phase (kg m<sup>-3</sup>)
  * Hygroscopicity parameter, &kappa;, for organic aerosol species (water uptake on inorganic species should be calculated with a thermodynamic model such as E-AIM, ISORROPIA, or similar)
  * Saturation concentration (&mu;g m<sup>-3</sup>)
  * Enthalpy of vaporization used to adjust the saturation concentration for temperature (J/mol)
  * Organic matter to organic carbon ratio for organic aerosol (g/g)
- [Properties of species emitted in CRACMM1](cracmm1/CRACMM1_2017_emiss_properties.csv) based on 2017 U.S. anthropogenic and biomass burning emissions as used by [Pye et al. 2023](https://doi.org/10.5194/acp-23-5043-2023)