ctsm5.4.013

[CTSM Gatekeeper]

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Tag name: ctsm5.4.013
Originator(s): erik (Erik Kluzek,UCAR/TSS,303-497-1326)
Date: Wed Jan 28 12:24:02 AM MST 2026
One-line Summary: Patch the Greenland snow hole with initial conditions for ne30 and tweak the C14 isotope latitudes

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

Point to tweaked C14 Isotope file so that the latitude line is straight and regrid doesn't change depending on processor count.

Also bring in a new ne30 finidat (Initial Conditions or IC) file so that the Greenland snow hole won't exist in ne30 initial conditions.


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]:

Fixes #3708 -- Patch Greenland snow "hole"
Fixes #3716 -- Use "tweaked" lat/lon C14 dataset so that the lattitude line will be straight and answers same on PE layout change

Notes of particular relevance for users
---------------------------------------

Caveats for users (e.g., need to interpolate initial conditions):
ONLY the ne30 IC file was updated, so this doesn't fix other resolutions
And the datm forcing still has the problem of too low snow over Greenland

Changes made to namelist defaults (e.g., changed parameter values):
Updated: stream_fldfilename_atm_c14 and stream_meshfile_atm_c14
Updated: finidat for ne30np4.pg3 grid (use the BgcCrop file for both BGC and SP cases)

Notes of particular relevance for developers:
---------------------------------------------

Changes to tests or testing: Removed some expected fails that have been passing


Testing summary: regular
----------------
[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

If the tag used for baseline comparisons was NOT the previous tag, note that here:


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

Changes answers relative to baseline: Yes! for f10 ciso cases, and ne30.pg3 cases

Summarize any changes to answers, i.e.,
- what code configurations: All
- what platforms/compilers: All
- nature of change:
minor for f10 Carbon Isotope C14 (the latitude line is straightened)
New IC for ne30.pg3 cases, so startup is different

Other details
-------------

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

https://github.com/ESCOMP/CTSM/pull/3711 "ne30 IC to patch Greenland snow hole, Tweaked C14 isotope file"

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