[Climate Land Model]

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Tag name: ctsm5.3.085
Originator(s): slevis (Samuel Levis,UCAR/TSS,303-665-1310)
Date: Fri Nov 14 11:08:54 AM MST 2025
One-line Summary: Merge b4b-dev to master

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

PRs
#3581 by Bill Sacks: Generalize some paths so unit testing works in a CESM checkout, previously assumed standalone CTSM checkout.
#3561 by Erik Kluzek: Start adding streams infrastructure for carbon isotopes.

Significant changes to scientifically-supported configurations
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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
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List of CTSM issues fixed (include CTSM Issue # and description) [one per line]:
Resolves #2837
Resolves #3502
Design notes in #3546
Some work on #3346

Testing summary:
----------------
[PASS means all tests PASS; OK means tests PASS other than expected fails.]

python testing (if python code has changed; see instructions in python/README.md; document testing done):

derecho - PASS

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

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

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

Changes answers relative to baseline:
No

Other details
-------------
Pull Requests that document the changes (include PR ids):
https://github.com/ESCOMP/ctsm/pull/3609

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[Climate Land Model]