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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

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