feature_brcoeff: slope-dependant breaking coefficient

[mpezerat]

Pull Request Summary

Computes a slope-dependant breaking coefficient for the depth-induced breaking source term

Description

Computes a slope-dependant breaking coefficient (BRCOEF) for the depth-induced breaking source term. A new flag (BRFLAG) is added to SDB1 namelist to choose between a constant breaking coefficient (BRFLAG=F, default value) prescribed with BJALFA parameter (same as before) or the adapting breaking coeff. (BRFLAG=T). In such case, the slope coefficient can be slightly adapted by the user through BJALFA parameter (default value 40).
Several studies demonstrate the robustness of this parameterization already implemented in the spectral wave model WWM (e.g. see Pezerat et al, 2021, OM), which allows to prevent an over dissipation by depth-induced breaking, especially in dissipative surf zone.
Please also include the following information:

• Add any suggestions for a reviewer: Aron Roland, Ali Abdolali
• Mention any labels that should be added: new feature
• Are answer changes expected from this PR? Please describe the changes and the reason why in addition to which of the following labels would apply: out_grd change

Issue(s) addressed

None

Commit Message

Slope dependant breaking coefficient.

Check list

• [x ] Branch is up to date with the authoritative repository (NOAA-EMC) develop branch.
• [x ] Checked the checklist for a developer submitting to develop.
• [x ] If a version number update is required, checked the updating version number checklist.
• [x ] If a new feature was added, a regression test for testing the new feature is added.

Testing

• How were these changes tested? This new feature has been tested on regtest tp18 (Haas and Warner) and personnal configuration using unstructured grid.
• Are the changes covered by regression tests? (If not, why? Do new tests need to be added?)
• Have the matrix regression tests been run (if yes, please note HPC and compiler)?
• Please indicate the expected changes in the regression test output, (Note the list of known non-identical tests.)
• Please provide the summary output of matrix.comp (matrix.Diff.txt, matrixCompFull.txt and matrixCompSummary.txt):