WRF-CHEM

This document provides an overview of the WRF-Chem-specific features of WRF-ensembly.

Initial conditions

The behaviour of real.exe and wrf.exe regarding the atm. composition initial condition is controlled by the chem_in_opt option in the &chem namelist. If this is set to 1:

  • real.exe will attempt to read the initial conditions from wrf_chem_input files (not sure exactly what happens) and will do weird things if they are not present.
  • wrf.exe will read the initial conditions from wrfinput_d01 files as every other variable.

And if this is set to 0: - real.exe will not read the initial conditions from wrf_chem_input and will write empty fields in wrfinput_d01. - wrf.exe will not read initial conditions for the chemistry fields.

Thus, if you are using interpolator-for-wrfchem to add initial conditions on already prepared wrfinput_d01 files, you should set chem_in_opt to 0 for real.exe and 1 for wrf.exe. This way, real.exe will not try to read the initial conditions from wrf_chem_input and will write empty fields in wrfinput_d01, while wrf.exe will read the initial conditions from wrfinput_d01 as every other variable.

To automate this behaviour, you can set manage_chem_in to true in your config.yml file (section data). This will automatically set chem_in_opt to the appropriate value depending on whether you are running real.exe or wrf.exe. If you set this to false, you will have to manually set chem_in_opt in your namelist.input file.