How to run WRF-CHEM without dust in chem_opt=202

[soumyajyoti jana]

Dear All

I am running WRFCHEM v4.5.2 to simulate the effect of dust on the tropical cyclone intensity. For that, I need to run WRF without dust. Currently, I am running chem_opt=202, made dust_op=0 in the 'namelist.input', and made 'oin_a0*' variables zero while running Mozbc using WACCM data. But still in the wrf output I am getting nonzero 'oin_a*' variables. So how do I run the model so the dust effect can be zero in the model?

Soumyajyoti Jana
Indian Institute of Tropical Meteorology, Pune, India

[Mary Barth]

Hi there,

The oin_a variables also receive emissions from anthropogenic sources. Perhaps that is what you are seeing. Have you analyzed your results to determine if dust emissions are zero? 

- Mary

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Mary Barth 

Senior Scientist   

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NSF - National Center for Atmospheric Research

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Boulder, CO 80307

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[soumyajyoti jana]

Hi Mary,

Thank you for your reply. I wasn't able to check if dust emissions were zero. 

Can you please tell me How to check if the dust emissions are zero or not in the output, as the output does not have any dust variable from chem_op=202? Do I need to change the registry?. I am attaching my namelist for your reference.

Thanks and regards

Soumyajyoti 

[Mary Barth]

Hello Dimeji,

I am not an expert on the dust module but my instinct is to go to the end of the module then provide a conditional statement to zero out the dust emissions in the region of interest. 

I added the wrf_chem google group to my reply in case someone else has a suggestion.

Mary

On Wed, Aug 20, 2025 at 2:19 AM Dimeji Sulaymon <dimejicatal...@gmail.com> wrote:

Dear Dr. Mary,

I want to quantify the contribution of both local and long-range dust emissions in a country using the WRF-Chem model. How can I deactivate the dust sources (local sources) of the country of interest in the WRF-Chem model? I read that I need to modify module_gocart_dust.F file to include a conditional statement that sets the dust emission flux to zero over the region of interest. Unfortunately, I don't know where exactly to modify in the module to achieve this. 

I'll be glad if you guide me on this.

Thanks and best regards,

Dimeji

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[Rajesh Kumar]

Hello Dimeji,

You can also set the value of EROD variable in your wrfinput file to zero over your region of interest. With this, there is no need to modify the code. 

Thanks,
Rajesh 

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Rajesh Kumar

Deputy Director

Research Applications Laboratory 

NSF National Center for Atmospheric Research (NSF NCAR)

E-mail: rku...@ucar.edu