This is the code as used for the results presented here. It is intended for use in the CESM1.0.5 version, to include carbon isotopes in the ocean model. In order to use this code with the standard CESM1.0.5 version of the CESM, all code included here needs to be placed in SourceMods/src.pop2/. 

To turn on the abiotic radiocarbon, abio_dic_dic14 needs to be added as option to the OCN_TRACER_MODULES variable in env_build in the case directory. To turn on the biotic carbon isotopes, the ecosystem and carbon isotope module need to be turned on by adding option ecosys and Ciso to OCN_TRACER_MODULES. For the ecosystem module active case we also used the "OCN_CHL_TYPE=prognostic in env_conf. The default set-up is for constant atmospheric CO2, d13C, and D14C values.

This code is development code and has not undergone CESM code review. Please cite the final GMD paper when using this code. 
Jahn, A., Lindsay, K., Giraud, X., Gruber, N., Otto-Bliesner, B. L., Liu, Z., and Brady, E. C.: Carbon isotopes in the ocean model of the Community Earth System Model (CESM1), Geosci. Model Dev., 2015.
 
A significantly updated version of the carbon isotope that works with the newest version of the CESM will be released as part of CESM2 in 2016. 