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Specify CAM initial files in a multi-instance CESM run

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Specify CAM initial files in a multi-instance CESM run

Hi there,


I want to run multi-instance CESM (for the test run, 2 instances) with different atmosphere initial conditions. So I first perform a hybrid run to obtain CAM initial files at different times (exp1). Then I carry out another hybrid run with 2 instances (exp2) based on the CAM initial and restart files of exp1.

For exp2, the related variables in env_run.xml are set as below:

  • RUN_TYPE = hybrid
  • RUN_REFCASE = exp1
  • RUN_REFDATE = 0001-01-03 (exp1 was run for 2 days from 0001-01-01)
  • RUN_REFTOD = 00000

After ./build, I copy all the files in the exp1 restart directory to the $RUNDIR of exp2, and I am sure that two different CAM initial files ( & with required names are provided. But after I submit exp2, I get many lines of the below error in cesm.log:


But in cam.buildnml.csh, I notice that below lines are included:

  • if ($RUN_TYPE == 'hybrid') then
  •   if (-e ${RUN_REFCASE}.cam${inst_string}.i.${RUN_REFDATE}-${RUN_REFTOD}.nc) then
  •     set ncdata = "ncdata='${RUN_REFCASE}.cam${inst_string}.i.${RUN_REFDATE}-${RUN_REFTOD}.nc'"
  •   else
  •     set ncdata = "ncdata='${RUN_REFCASE}.cam.i.${RUN_REFDATE}-${RUN_REFTOD}.nc'"
  •     if ($inst_string != "") echo "WARNING: $ncdata is being used"
  •   endif
  • endif

I do not understand why the model cannot find the 2 initial files I provided, and still try to find the default initial file, which leads to the above error.


After I specify the 2 provided initial files in 2 user_nl_000* files with ncdata, the model no longer get the above error, but I get many lines of below error in the cesm.log:

  • ERROR: aborting in ice-pio_ropen with invalid file

Besides, if I only run 1 instance the same way as above to specify the CAM initial file from a previous run, the model can complete successfully.


Can you help me with the above 2 questions which only found in the multi-instance scenario? (1. why the model cannot recognize the 2 CAM initial files I provided before specified with ncdata, 2. why I get the ice-pio_ropen error which not happened in the single instance run)


Your help will be much appreciated. Thanks!

Hi, I got the same problem. Did it work for? Best regards, Xiang-Yu

Xiangyu Li


You need to specify the initial file for the ice model in user_nl file.

Thanks a lot! I am new to CESM2.1.1. Did you mean "user_nl_cice"? Which variable should I specify in "user_nl_cice"?

Xiangyu Li


Yes. In user_nl_cice, and the variable is "ice_ic".

Thanks a lot! Using CESM2.1.1, copying all the restart files to inputdata/cesm2_init/${REFCASE}/0024-01-01 works. Of course, one needs to make sure that the ice files are indeed ouputted. But I got the following error? Did you see this? forrtl: severe (24): end-of-file during read, unit 97, file /cluster/work/users/xiangyuli/cesm/BW-control-190626-hybrid/run/./

Xiangyu Li


No, I have not used cesm2, and I have not seen this kind of error before.

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