Some questions about using different resolution OMI file in CMAQ5.3.2

Hi everyone.
I’m trying to run CMAQv5.3.2 simulations in East Asia.
I use the program which in the folder “CMAQ5.3.2/PREP/create_omi” to create high resolution OMI file.I set up nlat = 719, and nlon = 1441.
I have successfully run the case, but the result is very different with using the default OMI file.
When I check the IRR file, I found that the result using high resolution OMI file has some error.

I also try to use low resolution OMI file.I set up nlat = 361, and nlon = 361.
The result is very similar with using the default OMI file.

This picture is useing default OMI file(17x17).

This picture is useing OMI file(361x361).

This picture is useing OMI file(719x1441).

I have no idea why this problem happened.
Could you suggest me how to solve this problem?


How high is the resolution of the OMI data? Is it reasonable to generate data at the resolution you are attempting? Have you visualized the ozone column data, as done here?

The resolution of raw satellite is 0.25 degree.
The resolution of omi data is nlat = 719, and nlon = 1441.

Yes, I have visualized the ozone column data.
The result is very similar with the picture in PREP/create_omi/image_files.

This one is my omi data on 2018/05/10

This one is example in CMAQ folder.

And this one is the omi data on 2016/03/16.
This day is the second day in my simulations.


For the CMAQ OMI file with 719X1441 resolution, format statements may cause daily data to not be written on one line.

Please make and test the below changes to PREP/create_omi/src/module_utilities.f. The exact line numbers may be off based on your text editor but I hope that you understand these suggestions.

  1. Change lines 268 and 269 to

    550   format(a19,3600001f7.2)
    555   format(f10.4,f7.1,3600001i7)
  2. Change lines 647 and 648 to

    550   Format(2(a,tr1),3600001(f7.2,tr1))
    555   Format(f9.4,tr1,f7.1,tr1,3600001(i7,tr1))

Hi bhutzell,
Thank you for your help.
I have changed the code and created the new OMI file with 719X1441 resolution.
The output of IRR_10 became correct!
This picture is useing FIX OMI file(719x1441).

This fix is working for me as well!
Thank you so much for your help!


Hi bhutzell,
I used the program creat_omi to creat OMI file in 2020, and I changed the file path in CCTM run script, but there is no difference in O3 concentration between using the updated OMI file in 2020 and the default file ( I also want to know where the default OMI file is If I didn’t update OMI file in 2020).
set OMIpath = /home/CMAQv5.3.2/PREP/create_omi/scripts/output/omi_intel_2020_361X361
Did I call the file correctly? Could you help me? Thank you.

bj_2020_omi2020.csh (36.9 KB)

The default OMIfile is in the CCTM build directory. I cannot state why the ozone predictions did not change. Your run-script sets PHOTDIAG to “Y”. Please check how OZONE_COLUMN in the PHOTDIAG1 output file changes between using the two different OMIfiles.

Hi bhutzell,
I compared the OZONE_COLUMN in the PHOTDIAG1 file between the two files, they are different. Maybe updating the OMIfile doesn’t have much effect on the ozone prediction results in my simulation.
Thank you!

1 Like