Correct way of running WRF-Chem with chemistry

[Alice Burton]

Dear all,

I hope you are doing well.

I would like to clarify the correct workflow for running the WRF-Chem model after completing the WPS stage and generating the meteorological input files.

As I understand the process, after running WPS, the next step is to configure the namelist according to the study objectives. Then, with chem_opt set to zero, the real.exe program is executed. Afterward, anthropogenic and biogenic emission files are generated.

My question is regarding the steps that follow the preparation of emission files:

Once the emission files are ready, should chem_opt be activated (set to a non-zero value) and real.exe be executed again before running mozbc?

Or, alternatively, should mozbc be run immediately after generating the emission files, and only then chem_opt be activated before proceeding directly to wrf.exe?

I would greatly appreciate your guidance on the correct sequence to ensure a proper WRF-Chem simulation setup.

Thank you in advance for your support.

Best regards,

[Naser Mohammadzadeh]

Dear Alice,

Based on my experience, your understanding is generally correct.

After running WPS and generating the met_em files, you should first configure your namelist.input. Since WRF-Chem requires emissions (e.g., anthropogenic, biogenic), you initially need to turn off emissions (set them to zero) and then run real.exe.

Once real.exe finishes, it will generate the wrfinput and wrfbdy files. At this stage:

• You can apply MOZBC, if needed. MOZBC should be run immediately after real.exe, as it updates the wrfinput and wrfbdy files with chemical boundary conditions.
• After that, you should turn on emissions according to the chemistry scheme you are using.

Finally, you can proceed to run wrf.exe.

There is no need to run real.exe again after activating emissions.

I hope this helps clarify the workflow.

Best of luck with your simulations.

Kind regards,

Naser 

[Alice Burton]

Dear Naser,

Thank you so much for your help.

Kind regards,

[Gabriele Pfister]

Hello Alice

yes, after running WPS you will have to run real.exe to generate the wrfinput file(s). These are needed to generate the emissions and other inputs if you are using our processing tools. mozbc will add chemical fields to the generated wrfinput file(s), no need to re-run real.exe. Please see the README for mozbc for instructions. 

Afterwards you will run wrf.exe with chemistry active. 

Gabi

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================================
Gabriele Pfister

Atmospheric Chemistry Observations & Modeling (ACOM) Lab

NSF National Center for Atmospheric Research (NCAR)

Email: pfi...@ucar.edu

Work Phone: +1 303 497 2915

Web: https://staff.ucar.edu/users/pfister