update ChangeLog

Author: fvitt

doc/ChangeLog

@@ -1,4 +1,70 @@
+===============================================================
+
+Tag name: cam6_4_122
+Originator(s): fvitt
+Date: 2 Oct 2025
+One-line Summary: Enable prescribed MAM5 volcanic forcings; chemistry preprocessor fix
+Github PR URLs:
+ https://github.com/ESCOMP/CAM/pull/1375
+ https://github.com/ESCOMP/CAM/pull/1391
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+ Enable the use of prescribed MAM5 stratospheric volcanic aerosol forcings.
+ (Updates needed for prescribed MAM5 stratospheric aerosols #1187)
+
+ Fix an issue with the chemistry preprocessor on derecho.
+ (Chemistry preprocessor broken on derecho #1389)
+
+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: cacraigucar
+
+List all files eliminated: N/A
+
+List all files added and what they do:
+
+A       cime_config/testdefs/testmods_dirs/cam/outfrq9s_cam7_presc_volc/shell_commands
+A       cime_config/testdefs/testmods_dirs/cam/outfrq9s_cam7_presc_volc/user_nl_cam
+A       cime_config/testdefs/testmods_dirs/cam/outfrq9s_cam7_presc_volc/user_nl_clm
+ - add regression test for precscribed MAM5 stratospheric aerosols
 
+List all existing files that have been modified, and describe the changes:
+
+M       .gitmodules
+M       chem_proc
+ - update preprocessor to tag cam_proc5_0_07
+
+M       cime_config/testdefs/testlist_cam.xml
+ - regression test for precscribed MAM5 stratospheric aerosols
+
+M       src/chemistry/utils/prescribed_strataero.F90
+ - add ability to include precscribed MAM5 stratospheric aerosols
+
+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: All PASS
+
+derecho/nvhpc/aux_cam:
+    FAIL ERS_Ln9.ne30pg3_ne30pg3_mt232.FHISTC_LTso.derecho_nvhpc.cam-outfrq9s_gpu_default RUN time=441
+    - pre-existing failure -- might be related to https://github.com/ESCOMP/CAM/issues/1383
+
+izumi/nag/aux_cam: All PASS
+
+izumi/gnu/aux_cam: All PASS
+
+Summarize any changes to answers: bit-for-bit unchanged
+
+===============================================================
 ===============================================================
 
 Tag name: cam6_4_121