Add ChangeLog entry.

Author: nusbaume

doc/ChangeLog

@@ -1,5 +1,70 @@
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+Tag name: cam6_4_072
+Originator(s): sjsprecious
+Date: 28 February 2025
+One-line Summary: Fix broken RRTMGP GPU tests
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1260
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+Fixes #997 - RRTMGP not working with GPUs on derecho
+
+Describe any changes made to build system: N/A
+
+Describe any changes made to the namelist: N/A
+
+List any changes to the defaults for the boundary datasets: N/A
+
+Describe any substantial timing or memory changes: N/A
+
+Code reviewed by: nusbaume
+
+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       cime_config/testdefs/testmods_dirs/cam/outfrq9s_gpu_default/shell_commands
+M       cime_config/testdefs/testmods_dirs/cam/outfrq9s_gpu_pcols760/shell_commands
+ - Update Derecho GPU regression test to use RRTMGP.
+
+M       src/physics/rrtmgp/radiation.F90
+ - Update OpenACC calls to allow RRTMGP to run on Derecho's GPUs.
+
+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:
+
+ERP_Ln9.f09_f09_mg17.FCSD_HCO.derecho_intel.cam-outfrq9s (Overall: FAIL)
+SMS_Ld1.f09_f09_mg17.FCHIST_GC.derecho_intel.cam-outfrq1d (Overall: DIFF)
+ - pre-existing failures due to HEMCO not having reproducible results (issues #1018 and #856)
+
+SMS_D_Ln9.f19_f19_mg17.FXHIST.derecho_intel.cam-outfrq9s_amie (Overall: FAIL)
+SMS_D_Ln9_P1280x1.ne0CONUSne30x8_ne0CONUSne30x8_mt12.FCHIST.derecho_intel.cam-outfrq9s (Overall: FAIL)
+ - pre-existing failures due to build-namelist error requiring CLM/CTSM external update
+
+derecho/nvhpc/aux_cam:
+
+ERS_Ln9.ne30pg3_ne30pg3_mg17.F2000dev.derecho_nvhpc.cam-outfrq9s_gpu_default (Overall: DIFF)
+ - Expected namelist and baseline answer changes due to the addition of RRTMGP.
+
+izumi/nag/aux_cam: ALL PASS
+
+izumi/gnu/aux_cam: ALL PASS
+
+CAM tag used for the baseline comparison tests if different than previous
+tag:
+
+Summarize any changes to answers: b4b
+
+===============================================================
+===============================================================
+
 Tag name: cam6_4_071
 Originator(s): mwaxmonsky
 Date: 26 February 2025