CMAQ simulation at 36km and 12km

Hello all,

I am pretty new to CMAQ. I am doing a CMAQ simulation at 36km grid resolution. I have all input data (emission, ICBC, and MCIP) for this simulation.

However, I have to do another simulation at 12km grid resolution. I am wondering if you could help me how I could run the model for new grid resolution? Also, whether I should use new input data for 12km or can I use the same input data that I used for 36km?
In general, what is the difference between these two simulation? Which items should I change?

Thank you

To run CMAQ for a 12km grid resolution, you would need to have the WRF meteorology defined for the 12km grid, and also the emissions processed using SMOKE for that grid as well.
I would encourage you to take the CMAQ Online Training that is offered by the CMAS Center to learn more.
https://www.cmascenter.org/training/classes/online-cmaq-class.cfm

Hello,

Thank you for your help.

Just two more questions:
1- I have a working MCIP executable which is compatible with my CMAQ. I also have the GRIDDESC which contains the domain information for MCIP run. However, I need more information regarding how I should run MCIP. Can you please help me in this regard?

2- I have IC/BC for 36 km runs. I need to generate 12 km chemical IC/BC from 36 km runs. Can you please give me some ideas regarding how I can generate them?

Thank you in advance.

Hello,

Thank you for your help.

Just two more questions:
1- I have a working MCIP executable which is compatible with my CMAQ. I also have the GRIDDESC which contains the domain information for MCIP run. However, I need more information regarding how I should run MCIP. Can you please help me in this regard?

2- I have IC/BC for 36 km runs. I need to generate 12 km chemical IC/BC from 36 km runs. Can you please give me some ideas regarding how I can generate them?

Thank you in advance.

To run CMAQ, you need emissions and meteorology for the gridded modeling domain, and you need BCs for the perimeter. Earlier you said you have all the inputs for a 36-km simulation. Have you successfully run CMAQ to produce outputs at 36-km resolution?

If you next want to run CMAQ at 12-km resolution, you need meteorology and emissions inputs at 12-km resolution. You need to run WRF to generate meteorology for your 12-km grid, and you need to run SMOKE to generate emissions for the 12-km grid. MCIP will convert 12-km WRF output to a form that can be read by CMAQ, but it cannot generate 12-km meteorology from 36-km meteorology.

Thank you so much for your response.

Yes, I did. I successfully run CMAQ for 36-km grid resolution.

Now, for 12-km, I am working on WRF to generate met data for 12-km. However, for SMOKE, can you please give me more hint?
regarding MCIP, how can I use to to convert 12-km WRF output for CMAQ format?

Regarding IC/BC, can I use the same IC/BC for both 36-km and 12-km grid resolutions?

Thanks a lot

Depending on your specific application, a 12-km emissions dataset may be available for download from an EPA ftp server or from CMAS. Please check the SMOKE documentation and emissions tutorials. If you have specific questions, please post them in a new thread.

Hello.

I was wondering if you could help me with a similar question.

I have a WRF simulation with three nested domains with horizontal resolution of 15km, 3km and 1km respectively and my intention is to run CMAQ for the innermost domain.

I have successfully done this using WRF outputs for the innermost domain and an emission inventory with a 1km horizontal resolution.

I want to test CMAQ sensitivity to the horizontal resolution, so I wanted to re run CMAQ in the innermost domain with a 3km resolution. Of course, that would mean mapping my inventory to a 3km resolution, but I was wondering if the WRF output with a 1km resolution would still be useful as it has a finer resolution or I would have to re run WRF as well.

Hope you could help me
Thanks in advance

Hi SoIL,

  1. Obtain emissions for all three nested domains. In this context, “domains” refer to CMAQ domains that should have smaller sizes compared to the WRF domains.
  2. Generate meteorology inputs for the three domains by executing MCIP.
  3. Run CMAQ using a horizontal resolution of 15 km. Subsequently, run CMAQ/PREP/icon and CMAQ/PREP/bcon to generate Initial and Boundary Conditions (ICBC) for the 3 km domain.
  4. Run CMAQ with a horizontal resolution of 3 km. Then, execute icon and bcon to generate ICBC for the 1 km domain, following the steps described in the previous point.
  5. Run CMAQ with a horizontal resolution of 1 km.
  6. Evaluate the performance of the CMAQ model for all three different resolutions and determine which one best meets your needs.

If you wish to test the sensitivity of CMAQ to horizontal resolution, it is necessary to define a target area that is covered by the 15, 3, and 1 km domains, instead of utilizing the three nested domains mentioned earlier. Run CMAQ with different resolutions separately using the same input source, including ICBC, emissions, and meteorology. Analyze the model’s performance with different resolutions.

Please exercise caution when running WRF with a horizontal resolution below 4 km, as certain parametrization options, such as cu_physics, may not function properly at such fine scales.

I hope this information is helpful.

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