emiss_opt vs emiss_inpt_opt

Hello All,

Could someone explain the differences between emiss_opt and emiss_inpt_opt in the chem namelist? It seems that setting these right is crucial to accurate accounting for the chemical mechanism and emissions format, but I'm not sure what each setting does operationally.

Thanks,

Alex

HI Alex,

Yes this can be a bit confusing. Emiss_opt tells the model what emission species it expects to be read in (i.e., see emiss_opt in Registry/registry.chem). The subroutine called to read in the emissions is actually most often based on the chemical mechanism rather than the emiss_opt (e.g., see "gas_addemiss_select" in chem/emissions_driver.F and the called subroutine in module_emissions_anthropogenics.F). emiss_inpt_opt is generally only important if you are using emissions developed for one chemical mechanism (e.g., RACM) in a different mechanism (e.g., CBMZ). From the chem directory `grep emiss_inpt_opt *.F` and you will see that it only shows up in a few places. If you are confused my advice would be to find the instances of your mechanism name in the code, make sure your namelist options get you to that place in the code, and make sure you are emitting those species at runtime (e.g., you can set gaschemonoff = 0 and check wrfouts for those species). Hope this helps!

Cheers,

Jordan

Hello Jordan,

Thank you for this response! This does clarify the different purposes of these options. It sounds like emiss_opt relates a list of species to the model and emiss_inpt_opt is used to convert species across mechanisms if the input species don't match the mechanism.

Thanks Again,

Alex