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Problem when adding NO emission to ext_frc_specifier

koichi omi

koichi
New Member
Hello,

I'm trying to calculate the case with NO emission from aircraft to investigate its effects.
The calculation conditions are below.

COMPSET: FWHIST
RES: f09_f09_mg17
RUN_STARTDATE: 1979_0101
STOP_N = 13
STOP_OPTION = nmonths

I added NO emission file to "ext_frc_specifier" in the $CASEROOT/CaseDocs/atm_in.
However, when I execute this case, the calculation failed to converge.

Is there any suggestion to fix this problem?

Sincerely,
 

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  • cesm.log.200518-192559.txt
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mmills

CSEG and Liaisons
Staff member
Try reducing the model's dynamical time step. The number of dynamics time steps per physics time step is set by the namelist variable fv_nsplit. By default it is set to 8. You can try doubling it to 16. If that doesn't work, keep doubling. It may be possible to get to a stable condition, after which you can reduce fv_nsplit again.

The only restriction on the value of fv_nsplit is that it must be a multiple of fv_nspltrac (default value 2), which in turn must be a multiple of fv_nspltvrm (default value 2). Sometimes it can help to increase these other two namelist variables at the same time. For example, you could try putting these changes in your user_nl_cam:

fv_nsplit = 128
fv_nspltrac = 128
fv_nspltvrm = 128
 

koichi omi

koichi
New Member
Thank you so much for your advice!

I tried the following setting.

fv_nsplit = 4096
fv_nspltrac = 4096
fv_nspltvrm = 4096

But the calculation failed to converge.
Is there any other suggestion to fix this problem?

Or, is doubling "fv_nsplit" the only way to fix this problem?
 

mmills

CSEG and Liaisons
Staff member
So the model runs fine if you don't add the NO emissions? Perhaps you are adding a very large amount. Have you checked units to make sure your emissions make sense? Can you try starting with a reduced level of NO emissions?
 

koichi omi

koichi
New Member
Thank you for your reply.

The model runs successfully when I don't add the NO emission.
In addition, the model also runs successfully when I add one-third of the amount I want to add.
So, perhaps NO emission I added was a little large.

Is there any suggestion to run the model with increased level of NO emission?
 

mmills

CSEG and Liaisons
Staff member
You could try increasing the emissions steadily to allow chemistry to adjust.
 
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