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how to activate "ciso" option in the ecosystem model?

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how to activate "ciso" option in the ecosystem model?



Can someone help me on how to activate the "ciso" option in POP2 using CESM2 version, so i can get to see the carbon isotopes in my simulation?


As far as i see, it is not an option like "iage" or "ecosys" in env_build, and i see the namelist option  "ciso_on" in marbl_in, but what is the proper way/command to activate it?


Thanks a lot,



What version of CESM are you running? Prior to CESM 2.0, you enable carbon isotopes by running


$ ./xmlchange -a OCN_TRACER_MODULES=ciso


from your case directory. For CESM 2.0, create a file named user_nl_marbl and add the line


ciso_on = .true.


to it. Two things to note:


1. You need to have the ecosystem tracer module turned on (typically done by selecting a compset that uses ocean BGC)

2. If you have already built your case, you will need to do a clean build because CISO changes the ocean tracer count (and that's a build-time specification). I believe the following will work for all versions of CESM:


$ ./ --clean-all

$ ./


If --clean-all is not recognized as an option in your version of, try either "./ --clean" or just make a new case.

Michael Levy

CESM Software Engineering Group (CSEG)

ML-417, x1748


Hi Michael,


Thanks a lot. It worked now.

I am using the CESM2 version so i created the user_nl_marbl file and put the ciso_on=.true. flag there.


Thanks again


Dear all,

I am trying to produce a simulation using POP2 and CESM2 version with carbon isotopes in my simulation using the "use_ciso=.true." option set in user_nl_marbl.
My case compiles just fine but during execution I encouter the error:

POP aborting...
Error in getting varid for netCDF field DI13C_CUR

Looking into this, I find that CESM2 is trying to read DI13C_CUR from /inputfiles/cesm2_init/b.e20.B1850.f09_g17.pi_control.all.297/0130-01-01/ right before the crash. However, if I look at the information of that .nc file, DI13C_CUR is not found. A colleage was able to run the ciso option a couple of weeks back, so I was wondering if there have been any changes to the input data repository lately?

I am thankful for any suggestions that help me solve this issue.


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