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@Hallberg-NOAA Hallberg-NOAA commented Jul 22, 2025

This series of 3 commits updates the defaults for a total of 21 runtime parameters, and obsoletes another 7 runtime parameters, as agreed to in MOM6 consortium-wide meetings on July 29, 2024, December 16, 2024 and June 2, 2025.
The default equation of state is now EQN_OF_STATE = "WRIGHT_FULL", in place of the buggy previous default of "WRIGHT".

The 8 answer date parameters REGRIDDING_ANSWER_DATE, TIDES_ANSWER_DATE, WAVE_INTERFACE_ANSWER_DATE, MEKE_GM_SRC_ANSWER_DATE, NDIFF_ANSWER_DATE, KPP%ANSWER_DATE, HOR_DIFF_ANSWER_DATE and LOTW_BBL_ANSWER_DATE all now take their default values from DEFAULT_ANSWER_DATE.

The bug-retention parameters MEKE_GM_SRC_ALT_SLOPE_BUG, HOR_DIFF_LIMIT_BUG,
BACKSCATTER_UNDERBOUND, DETERMINE_TEMP_CONVERGENCE_BUG, LA_MISALIGNMENT_BUG,
IDL_HURR_SCM_EDGE_TAPER_BUG, VISC_REM_BUG and FRICTWORK_BUG are now false by
default.

With these changes, MASS_WEIGHT_IN_PRESSURE_GRADIENT_TOP now takes its default value from the setting for MASS_WEIGHT_IN_PRESSURE_GRADIENT. Similarly, the default for DRAG_DIFFUSIVITY_ANSWER_DATE is now set to follow SET_DIFF_ANSWER_DATE. KELVIN_WAVE_VEL_NUDGING_TIMESCALE is now set to a negative value by default, forcing the user to provide a valid value at runtime. SHELFWAVE_CORRECT_AMPLITUDE now defaults to True.

The parameters BETTER_BOUND_KH, BETTER_BOUND_AH, USE_DIABATIC_TIME_BUG, FIX_UNSPLIT_DT_VISC_BUG, CFL_BASED_TRUNCATIONS and KD_BACKGROUND_VIA_KDML_BUG have all been obsoleted and are no longer valid MOM6 runtime parameters.

These changes can change answers if any of the impacted parameters are taking their default values, but answers will not change if they are set explicitly. The easiest way to determine what parameters must now be set explicitly to
retain existing answers is to run a configuration twice with versions of the model from before and after this PR, and to compare the MOM_parameter_doc.all files to determine which parameters have been changed by the changing defaults.

The specific commits in this PR include:

  • 5ac077fad +Obsoleted 7 parameters, including BETTER_BOUND_KH
  • 05311b535 *Update defaults for 6 parameters (VISC_REM_BUG, )
  • 62d74dfc1 *Update defaults for EQN_OF_STATE and 14 parameters

@Hallberg-NOAA Hallberg-NOAA added answer-changing A change in results (actual or potential) Parameter change Input parameter changes (addition, removal, or description) labels Jul 22, 2025
@Hallberg-NOAA Hallberg-NOAA changed the title Update param defaults 2025 +*Update parameter defaults for 2024 and 2025, including EQN_OF_STATE Jul 22, 2025
@Hallberg-NOAA Hallberg-NOAA force-pushed the update_param_defaults_2025 branch from 663d389 to ca0a081 Compare July 28, 2025 13:44
  Updated the default values of 15 runtime parameters, as agreed upon in a MOM6
consortium wide conversations on July 29, 2024 and December 16, 2024.  The most
prominent of these is that the default equation of state is now EQN_OF_STATE =
"WRIGHT_FULL", in place of the buggy previous default of "WRIGHT".

  The 8 answer date parameters REGRIDDING_ANSWER_DATE, TIDES_ANSWER_DATE,
WAVE_INTERFACE_ANSWER_DATE, MEKE_GM_SRC_ANSWER_DATE, NDIFF_ANSWER_DATE,
KPP%ANSWER_DATE, HOR_DIFF_ANSWER_DATE and LOTW_BBL_ANSWER_DATE all now take
their default values from DEFAULT_ANSWER_DATE.

  The bug-retention parameters MEKE_GM_SRC_ALT_SLOPE_BUG, HOR_DIFF_LIMIT_BUG,
BACKSCATTER_UNDERBOUND, DETERMINE_TEMP_CONVERGENCE_BUG, LA_MISALIGNMENT_BUG and
IDL_HURR_SCM_EDGE_TAPER_BUG are now false by default.

  The MOM_input files for the test cases in the `.testing/tc[01234]` directories
were updated to explicitly set all of these parameters to their previous default
values if they are used in the relevant cases, as well as parameters that will
be change following discussions from June 2, 2205.

  Bitwise identical answers are recovered if all 15 of these parameters are set
explicitly, but answers can change if any of these parameters take default
values.  All of these default changes are the consensus decision of
consortium-wise MOM6 dev calls.
  Updated the default values of 6 runtime parameters, as agreed upon in a MOM6
consortium wide conversations on June 2, 2025. VISC_REM_BUG and FRICTWORK_BUG
are now false by default. MASS_WEIGHT_IN_PRESSURE_GRADIENT_TOP now takes its
default value from the setting for MASS_WEIGHT_IN_PRESSURE_GRADIENT.  Similarly,
the default for DRAG_DIFFUSIVITY_ANSWER_DATE is now set to follow
SET_DIFF_ANSWER_DATE. KELVIN_WAVE_VEL_NUDGING_TIMESCALE is now set to a negative
value by default, forcing the user to provide a valid value at runtime.
SHELFWAVE_CORRECT_AMPLITUDE now defaults to True.
  Obsoleted 7 runtime parameters that always take the same value, as agreed upon
in a MOM6 consortium wide conversations on June 2, 2025, and added tests to
catch these parameters in MOM_obsolete_params.  The parameters that were
obsoleted include BETTER_BOUND_KH, BETTER_BOUND_AH, USE_DIABATIC_TIME_BUG,
FIX_UNSPLIT_DT_VISC_BUG, CFL_BASED_TRUNCATIONS and KD_BACKGROUND_VIA_KDML_BUG.
The runtime parameter MAXVEL still exists, but it is logged in a different order
than before, changing the contents of the MOM_parameter_doc files. All answers
are bitwise identical in cases that run, but cases that use these parameters
will experience a fatal error.
@Hallberg-NOAA Hallberg-NOAA force-pushed the update_param_defaults_2025 branch from ca0a081 to 5ac077f Compare August 5, 2025 14:31
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This PR has now been added as a PR directly to main on MOM-ocean in PR mom-ocean#1670. It is being retained as a PR to dev/gfdl for now to facilitate pipeline testing.

@Hallberg-NOAA Hallberg-NOAA marked this pull request as draft August 6, 2025 08:41
  Added code to set all intent(out) arguments in the stub version of the
MOM_generic_tracer routines MOM_generic_tracer_stock(),
MOM_generic_tracer_min_max() and MOM_generic_tracer_get() to avoid compile-time
warnings.  These stub routines are never supposed to be used, and there would be
a fatal error during the registration phase if they are used.  The values that
are set in these stub routines are extremely large or otherwise nonsensical so
that it would make it easier to debug them if they were used accidentally.  All
answers are bitwise identical in any cases that run successfully.
@marshallward marshallward merged commit 56a772c into NOAA-GFDL:dev/gfdl Aug 21, 2025
52 checks passed
@Hallberg-NOAA Hallberg-NOAA deleted the update_param_defaults_2025 branch August 21, 2025 15:22
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