Define a new history field e.g., the relaxation temperature profile
Note, these instructions are only valid for the 2018 CESM2 release. If you wish to run the Held-Suarez configuration prior to the CESM2 release, please contact Isla Simpson (firstname.lastname@example.org)
An example of source code modifications to output the relaxation temperature profile as a history field can be downloaded here here. Here, the original modules are named filename-ORIG and the modified modules are named filename. Users can compare these two files to identify the modifications that have been made and should then translate these modifications into the appropriate module versions within their own CESM version. The source code modifications provided here are designed to work with CESM2, but users should be able to make similar modifications with subsequent model releases, although the exact location required for code modifications may differ slightly.
The result of these modifications are that an additional history field containing the equilibrium temperature profile (TREF) is written to the output when specified as an output field in $CASEDIR/user_nl_cam. See e.g., information on altering CAM output