Adding Tracer Emissions

Hello All!

I'm trying to run a instance of WRF where I am able to use CH4 emissions (I'm open to either using it as a tracer or as a reactive species). Based on the registry, of the basic mechanisms, only RACM includes CH4 in their scheme. This isn't my first choice scheme and I would love some guidance concerning how to add a Tracer. Does anyone have any resources they could share that would help ease the process of adding CH4 as a tracer to a WRF-CHEM run?

Thank You,

Alex

Hi Alex,

Several other mechanisms include CH4, including RADM2, MOZART, and CB* mechanisms. To emit CH4, you will need to add e_ch4 to the registry under the emission option that you use, and make sure that CH4 emissions are added to the chemical tendency arrays in the appropriate emission driver (e.g., module_emissions_anthropogenics.F). Also, be aware that depending on the choice of mechanism, there will likely be code that sets a constant CH4 concentration since it is not normally emitted.

Jordan

Hello Jordan,

Thank you for this response! Based on your response, it sounds like it's possible to add CH4 emissions but that it might be a bit more complicated to have them incorporated correctly. Do you know of any documentation that might provide guidinace around modifications to chemical tendency arrays?

Thanks!

Alex

Hi Alex,

I'm not aware of any specific documentation for that procedure, though this may help: https://ruc.noaa.gov/wrf/wrf-chem/wrf_tutorial_2015/WRF_CHEM_Chemistry.pdf

In general, you will need to modify these files:

Registry/registry.chem (if your choice of emiss_opt and chem_opt does not have CH4 emissions or is advected, respectively)
chem/module_input_chem_data.F (to handle initial and boundary conditions)
chem/chemics_init.F (to make sure ch4 isn't set to a constant everywhere for your choice of mechansim)
chem/module_emissions_anthropogenics.F (or the subroutine called for your chem_opt/emiss_opt)

Cheers,

Jordan

Hello Jordan,

Thanks for posting this guidance and the link to the presentation. I appreciate you taking the time to help!

Cheers,

Alex