ctsm5.4.005

[CTSM Gatekeeper]

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Tag name: ctsm5.4.005
Originator(s): rgknox (Ryan Knox, LAWRENCE BERKELEY NATIONAL LABORATORY, rgk...@lbl.gov)
Date: Fri Dec 19 11:33:00 AM MST 2025
One-line Summary: FATES JSON parameter files

Purpose and description of changes
----------------------------------

These changes accommodate a JSON format to the FATES parameter file.

New documentation has been updated in the FATES User's Guide:
https://fates-users-guide.readthedocs.io/en/latest/user/Parameter-File.html


Significant changes to scientifically-supported configurations
--------------------------------------------------------------

Does this tag change answers significantly for any of the following physics configurations?

(Details of any changes will be given in the "Answer changes" section below.)

[Put an [X] in the box for any configuration with significant answer changes.]

[ ] clm6_0

[ ] clm5_0

[ ] ctsm5_0-nwp

[ ] clm4_5


Bugs fixed
----------
List of CTSM issues fixed (include CTSM Issue # and description) [one per line]:
Work on #2126

Notes of particular relevance for users
---------------------------------------
Caveats for users (e.g., need to interpolate initial conditions): Please see documentation.

Changes to CTSM's user interface (e.g., new/renamed XML or namelist variables): Yes, the FATES parameter file is now a different format. Again, see documentation.

Changes made to namelist defaults (e.g., changed parameter values): The path to the FATES default parameter file is now the file FATES version control, i.e src/fates/parameter_files/fates_params_default.json

Changes to the datasets (e.g., parameter, surface or initial files): No values changed

Changes to documentation: https://fates-users-guide.readthedocs.io/en/latest/user/users-guide.html


Notes of particular relevance for developers:
---------------------------------------------
The API related to parameter I/O between FATES and CTSM is way less complicated. CTSM simply passes FATES the file-path to the parameter file, FATES handles the rest.


Testing summary:
----------------

[PASS means all tests PASS; OK means tests PASS other than expected fails.]

build-namelist tests (if CLMBuildNamelist.pm has changed):

derecho - OK

regular tests (aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing):

derecho ----- OK
izumi ------- OK

fates tests: (give name of baseline if different from CTSM tagname, normally fates baselines are fates-<FATES TAG>-<CTSM TAG>)
derecho ----- OK
izumi ------- OK compared against fates-sci.1.88.0_api.42.0.0-ctsm5.4.001


Answer changes
--------------

Changes answers relative to baseline: Yes

- The FATES JSON updates have B4B results in all configurations (i.e. no changes).
- FATES tag sci.1.88.6_api.42.0.0, a key bug fix, generated subtle but non-signficant answer changes
in non-SP and non-st3 FATES configurations: https://github.com/NGEET/fates/releases/tag/sci.1.88.6_api.42.0.0

Other details
-------------
List any git submodules updated (cime, rtm, mosart, cism, fates, etc.):

fates from sci.1.88.0_api.42.0.0 to ... sci.1.89.0_api.43.0.0

Pull Requests that document the changes (include PR ids):
https://github.com/ESCOMP/ctsm/pull/3570
https://github.com/NGEET/fates/pull/1493

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