Update changelog

Author: ekluzek

doc/ChangeLog

@@ -1,4 +1,120 @@
 ===============================================================
+Tag name: ctsm5.4.018
+Originator(s): erik (Erik Kluzek,UCAR/TSS,303-497-1326)
+Date: Wed Feb 11 11:54:03 AM MST 2026
+One-line Summary: Quick fix so that we can use Nitrogen Deposition sent from the ATM model
+
+Purpose and description of changes
+----------------------------------
+
+Add the ndep_inparm namelist to drv_flds_in, so that CTSM can turn on ndep from the ATM model. Also turn on using the ndep from the ATM model for the cam LndTuningMode testmods. And make sure ndep comes from CAM when we are coupled to CAM.
+
+Significant changes to scientifically-supported configurations
+--------------------------------------------------------------
+
+Does this tag change answers significantly for any of the following physics configurations? No
+(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 Add ndep_inparm namelist to drv_flds_in #3742
+ Fixes When coupled to CAM, ndep is still read in from CTSM rather than using what CAM is sending #3737
+ Fixes Ndep from ATM is now hard coded to 2 fields #3743
+ Fixes Have testmods with cam LndTuningMode use ndep from ATM #3744
+ Fixes Add CLM_NDEP_FROM_CPL XML variable #3747
+ Fixes Difference between ndep from CTSM streams and from DATM is significant #3748
+ Some work on Move settings from use_cases to namelist_defaults #605
+
+Notes of particular relevance for users
+---------------------------------------
+Caveats for users (e.g., need to interpolate initial conditions):
+   Now you can trigger whether Nitrogen Deposition is coming from the ATM model or read inside of CTSM
+   (before it was ALWAYS read in)
+   This only matters for Bgc or BgcCrop compsets
+   You can see if ndep is coming from ATM or CTSM by doing this in your case:
+      ./xmlquery CLM_NDEP_FROM_CPL
+      # (will be TRUE if coming from either DATM or CAM, FALSE if read internally in CTSM
+      grep ndep CaseDocs/*
+      # If the above is FALSE for an I compset you'll see matches in: datm_in and lnd_in
+      # If the above is TRUE when coupled to CAM you'll see matches in: atm_in and drv_flds_in
+      # (and in lnd_in, but just for the empty namelist: &ndepdyn_nml)
+
+      The lnd.log file also will explicitly say whether ndep is coming from ATM or read by CTSM
+
+Changes to CTSM's user interface (e.g., new/renamed XML or namelist variables):
+   New XML variable: CLM_NDEP_FROM_CPL
+   For I compsets this is set to FALSE, but when coupled to CAM it's set to TRUE
+
+Changes made to namelist defaults (e.g., changed parameter values):
+   None from the user perspective, unless you try to run with CLM_NML_USE_CASE==UNSET
+
+Changes to documentation:
+  Updated notes on ndep
+
+Notes of particular relevance for developers:
+---------------------------------------------
+
+Caveats for developers (e.g., code that is duplicated that requires double maintenance):
+   Settings for ndep moved from the use_case files to namelist_defaults_ctsm
+   ndep_list added to namelist_definition_drv_flds.xml
+
+Changes to tests or testing:
+   clm*cam*LndTuningMode testmods changed to have ndep come from the ATM model (so DATM)
+   build-namelist tester updated to accomidate the addition of CLM_NDEP_FROM_CPL
+
+
+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 (some changes relative to ctsm5.4.018)
+
+  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 (just when coupled to CAM or the CAM LndTuningMode testmods are used)
+
+  Summarize any changes to answers, i.e.,
+    - what code configurations: Only BGC cases for when Coupled to CAM / CAM LND_TUNING_MODE
+    - what platforms/compilers: All
+    - nature of change: same climate, changes Nitrogen deposition
+
+  We didn't run simulations but as the change to ndep is a normalized RMS of 1.e-4 we felt it should be OK
+
+Other details
+-------------
+
+Pull Requests that document the changes (include PR ids):
+(https://github.com/ESCOMP/ctsm/pull)
+
+  #3745 -- allows ndep to come from ATM model
+
+===============================================================
+===============================================================
 Tag name: ctsm5.4.017
 Originator(s): slevis (Samuel Levis,UCAR/TSS,303-665-1310)
 Date: Mon Feb  9 12:34:51 PM MST 2026

doc/ChangeSum

@@ -1,5 +1,6 @@
 Tag                   Who      Date  Summary
 ============================================================================================================================
+       ctsm5.4.018     erik 02/11/2026 Quick fix so that we can use Nitrogen Deposition sent from the ATM model
        ctsm5.4.017   slevis 02/09/2026 Introduce CRUJRA2024b datm option (Greenand snow hole filled)
        ctsm5.4.016 samrabin 02/06/2026 Merge b4b-dev to master
        ctsm5.4.015     erik 02/03/2026 Update CISM to latest version with answer changes