Is there a tutorial about modified AEROSOL_CHEMISTRY.F ?

Hi. I want to add a heterogeneous reactions in CMAQ. But I have some difficulties modifying this file. I am not particularly familiar with the F language, but I have a need to change this file. I want to add a few reactions where aerosols consume (absorb) free radicals, but this seems to require modifying many parts of this source code. Is there a tutorial available? Or any explanation of this source code?

I would recommend looking into the CHEMMECH utility routine described in the following links.


What confused me is all routine seems like only deal with photo chemical reactions but not heterogeneous reactions. This is the most detailed tutorial about hetergeneous reaction?


Hello. You may be able to use an existing heterogeneous reaction as a template. For a very simple reaction, see uptake of glyoxal (GLY) to aerosol (AGLYJ) in the HET_GLY reaction on line 445 of the cb6r5 with ae7 mechanism. The rate of the reaction is specified by the <HETERO_GLY> label. HETERO_GLY is calculated in AEROSOL_CHEMISTRY.F as a function of aerosol surface area, gas-phase diffusion, and an uptake coefficient. Since the mechanism file mech_cb6r5_ae7_aq.def isn’t actually used in the CMAQ executable, you will need to propagate the mechanism to the RXNS* files using CHEMMECH as Liz mentions. If you want to use the ebi solver, you will also need to run create_ebi. You can run CHEMMECH and create_ebi manually, or you can turn on the build_mech flag on line 49 of the bldit_cctm.csh file. build_mech will run the CHEMMECH and create_ebi functionality for you (just double check you use the output files). In short:

  • add your reaction to the mech.def file with a string label for the rate
  • update AEROSOL_CHEMISTRY.F to calculate the rate
  • update the gas phase or other relevant species name lists (GC*.nml; AE*.nml, etc) if you have a new species
  • run CHEMMECH and create_ebi OR turn on bldit_mech when you build CMAQ so the chemistry in mech.def is propagated to RXNS*.F90 files and the ebi solver files


Very thanks for your help!!

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