*+Add ePBL bottom boundary layer mixing option #717
Commits on Dec 2, 2024
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*Fix a bug when EPBL_ORIGINAL_PE_CALC is false
Corrected a bug that causes ePBL column to set the wrong variable and then use an uninitialized variable when EPBL_ORIGINAL_PE_CALC is set to false. This bug was present when the EPBL_ORIGINAL_PE_CALC was first added on Sept. 30, 2016, but it was not detected because only the default case with EPBL_ORIGINAL_PE_CALC = True appears to being used or tested. Any runs that used this code with debugging compile options would have trapped it immediately. This will change answers when EPBL_ORIGINAL_PE_CALC is false.
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+Add EPBL_MLD_ITER_BUG runtime parameter
Added the new runtime parameter EPBL_MLD_ITER_BUG that can be set to false to correct buggy logic that gives the wrong bounds for the next iteration when USE_MLD_ITERATION is true and successive guesses increase by exactly EPBL_MLD_TOLERANCE. By default all answers are bitwise identical, but there is a new runtime parameter in some MOM_parameter_doc files.
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+Add run-time ability to debug ePBL sensitivities
Added the ability to passively run ePBL_column twice in a diagnostic mode and then provide diagnostics of the differences in the diffusivities and boundary layer depths that are generated with the two options. This is controlled by the new runtime parameter EPBL_OPTIONS_DIFF, which is an integer that specifies which options to change or 0 (the default) to disable this capability. Associated with this are the new diagnostics ePBL_opt_diff_Kd_ePBL, ePBL_opt_maxdiff_Kd_ePBL and ePBL_opt_diff_h_ML, which only are registered when the differencing is enabled. For now, only changes associated with the settings of EPBL_ORIGINAL_PE_CALC and EPBL_ANSWER_DATE can be evaluated, but this list will grow as new options are added. As a part of these changes, there were some other reforms to the way that MOM_energetic_PBL handles diagnostics, with the 2-d and 3-d arrays changed from allocatable arrays with enduring memory commitments in the energetic_PBL_CS type into simple arrays in energetic_PBL, relying on the fact that compilers will be smart enough to avoid actually allocating this memory when it is unused to avoid expanding the overall memory requirements of MOM6. A number of allocate and deallocate calls were eliminated by these changes. In addition, explicit 'units=' descriptors were added to numerous register_diag_field calls to help identify inconsistent conversion factors. Also, the diagnostic of the number of boundary layer depth iterations was added to the ePBL_column_diags, which enabled the intent of the CS and G arguments to ePBL_column to be changed to intent(in). The unnecessary extra logic associated with the use of the OBL_converged variable in ePBL_column was eliminated, but the results are uneffected. Because the MOM_parameter_doc files were changing anyway, and because this commit is only a diagnostic change, about 6 spelling errors were corrected in ePBL parameter descriptions as a part of this commit. All answers are bitwise identical, but there is a new runtime parameter and there may be new diagnostics depending on the choice of a non-default value for that new parameter.
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+Add and test find_Kd_from_PE_chg
Added the new internal subroutine find_Kd_from_PE_chg inside of the MOM_energetic_PBL module to directly calculate an increment in the diapycnal diffusivity from an energy input. This can be used when ePBL does not convert released mean kinetic energy into turbulent kinetic energy (i.e., if MKE_TO_TKE_EFFIC = 0.) and is more efficient than the more general iterative approach. To preserve old answers, this new option is only enabled for the surface boundary layer when the new runtime parameter DIRECT_EPBL_MIXING_CALC is set to true. This new option can be tested passively by setting EPBL_OPTIONS_DIFF to 3 in a run that uses ePBL. By default all answers are bitwise identical, but there is a new runtime parameter in some of the MOM_parameter_doc files.
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+(*)Add ePBL bottom boundary mixing option
Add the option to do energetically consistent bottom boundary layer mixing with the new routine ePBL_BBL_column. ePBL_BBL_column is closely based on the surface-focused ePBL mixing in ePBL_column, but without adding convective instability driven mixing or mean-TKE driven mixing to avoid possible double-counting. This new option is enabled by setting the new runtime parameter EPBL_BBL_EFFIC to be positive. If both EPBL_BBL_EFFIC and BBL_EFFIC are set to positive values, there is a risk of double-counting, but this case is not being trapped for now. The changes include the addition of a new mandatory vertvisc_type argument to the publicly visible routine energetic_PBL. When this new ePBL bottom boundary layer mixing option is enabled, there are several new diagnostics available that are related to bottom boundary layer mixing. Several new checksum calls were also added with this new option when DEBUG = True. The MOM_parameter_doc files are altered by the addition of two new runtime parameters, and by the correction of several spelling errors in the descriptions of other ePBL parameters. By default, all answers are bitwise identical.
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+Add DECAY_ADJUSTED_BBL_TKE option for ePBL BBL
Added the ability to modify the bottom boundary layer TKE budget to account for an exponential decay of TKE away from the boundary and the fact that when the diffusivity is increased at an interface, it causes an increased buoyancy flux that varies linearly throughout a well mixed bottom boundary layer and through the layer above. This new capability is enabled by the new runtime parameter DECAY_ADJUSTED_BBL_TKE and is implemented via the new internal function exp_decay_TKE_adjust. In addition, this commit adds 9 bottom-boundary layer specific run-time parameters that are analogous to parameters that set the properties of the surface-driven mixing, and take their defaults from them, but can now be set independently for the bottom boundary layer. The inefficient option to use bisection to estimate the bottom boundary layer depth was eliminated, as it certain that it is not being used yet in any cases, and it should be deprecated for the estimation of the surface boundary layer. By default, all answers are bitwise identical, but there are up to 10 new runtime parameters that will appear in some MOM_parameter_doc files.
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