Draft ChangeLog.

Author: jimmielin

doc/ChangeLog

@@ -1,12 +1,13 @@
-Tag name: cam6_4_xxx
-Originator(s): pel
-Date:
-One-line Summary: Fix (energy) bug in physics-dynamics coupling
-Github PR URL: https://github.com/ESCOMP/CAM/pull/
+Tag name: cam6_4_173
+Originator(s): pel, peverwhee, hplin
+Date: 15 May 2026
+One-line Summary: Fix energy bugs in physics-dynamics coupling, RRTMGP diagnostics, and ZM scheme
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1554
 
 Purpose of changes (include the issue number and title text for each relevant GitHub issue):
-
-  Fix (energy) bug in physics-dynamics coupling -- issue #1551
+- Closes #1551 - Bug in physics tendency scaling
+- Closes #1553 - RRTMGP diagnostic net_flx bug
+- Closes #1550 - ZM scheme no longer conserving energy
 
 Describe any changes made to build system: N/A
 
@@ -16,20 +17,56 @@ List any changes to the defaults for the boundary datasets: N/A
 
 Describe any substantial timing or memory changes: N/A
 
-Code reviewed by:
+Code reviewed by: nusbaume, cacraig (atmos_phys)
 
 List all files eliminated: N/A
 
 List all files added and what they do: N/A
 
 List all existing files that have been modified, and describe the changes:
 
+M       .gitmodules
+ - Update atmos_phys external to atmos_phys0_21_003
+
+M       src/atmos_phys (external)
+ - Update to atmos_phys0_21_003: fix ZM scheme factor for energy conservation
+
+M       src/physics/cam/physpkg.F90
+M       src/physics/cam7/physpkg.F90
+M       src/physics/simple/physpkg.F90
+ - Move cam_thermo_water_update call to after state is saved (inside the
+   .not.moist_mixing_ratio_dycore block) so that cp/cv is updated using
+   post-physics water variables for energy diagnostics only
+ - Save and restore cp_or_cv_dycore along with state tracers/pdel/ps so
+   the energy-diagnostic-only call to physics_dme_adjust does not corrupt
+   the cp/cv used by the dycore energy consistency adjustment
+
+M       src/physics/rrtmgp/radiation.F90
+ - Move zeroing of flns/flnt (longwave net flux at surface/TOA) from
+   before the shortwave block to before the longwave block, fixing
+   incorrect net_flx diagnostics
+
+M       src/utils/air_composition.F90
+ - Remove 'protected' attribute from cp_or_cv_dycore to allow physpkg to
+   save/restore it across the diagnostic physics_dme_adjust call
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
 
+derecho/intel/aux_cam:
 
+derecho/nvhpc/aux_cam:
+
+izumi/nag/aux_cam:
+
+izumi/gnu/aux_cam:
+
+Summarize any changes to answers:
 Expecting failures against baseline for all tests using SE dycore
 (only tests without moisture should not fail)
 
-
 ===============================================================
 
 Tag name: cam6_4_171