Ww3 gse2

[aronroland]

Pull Request Summary

Description

Solves the anisotropic diffusion equation following Booij and Holthuijsen (1987, hereafter denoted as BH87). We apply a simple Galerkin scheme for the non-diagonal terms and treat the diagonal terms using linear shape functions. The scheme has been tested in various global setups. We have further developed the filter functions introduced by Hendrik, e.g., we fade out the diffusion coefficients when waves reach shallow water. This is crucial, as we have much higher resolution near the coastlines within the multiscale approach. An implicit implementation could also be a future option, but this, from my point of view, is not fruitful. For the interested reader, the justification for this is given by Peter Janssen in his JCP paper. Why use higher order schemes and then degrade them by adding diffusion? To keep it short, if the resolution goes to lim -> 0, the diffusion coefficient goes to infinity, which renders this approach not really optimal. We must keep in mind that all of this is only done since the model is limited by the finite bandwidth approximation, which was chosen to discretize the wave spectra. For example, when increasing the spectral resolution, the GSE effect vanishes. In conclusion, we can say that all this is not needed if the spectral resolution is high enough, which was not affordable at the time when this was developed. Nowadays, we must reevaluate the whole approach.

Please also include the following information:

• Add any suggestions for a reviewer
  none
• Mention any labels that should be added: bug, documentation, enhancement, new feature
  enhancement
• 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: mod_def change, out_grd change, out_pnt change, restart file change, Regression test
  No!

Issue(s) addressed

#930

Commit Message

adding gse alleviation for ug grids.

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.
• 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.
  This needs further attention by Jessica, we need to chose, which test we want.

Testing

• How were these changes tested?
  Global runs with significant GSE.
• Are the changes covered by regression tests? (If not, why? Do new tests need to be added?)
  Not yet see above.
• Have the matrix regression tests been run (if yes, please note HPC and compiler)?
  Will be done by ERDC
• Please indicate the expected changes in the regression test output, (Note the list of known non-identical tests.)
  None
• Please provide the summary output of matrix.comp (matrix.Diff.txt, matrixCompFull.txt and matrixCompSummary.txt):
  Will follow ...

[JessicaMeixner-NOAA]

@aronroland thank you for submitting this PR! As soon as the testing information from ERDC is added we'll start the tests and review.

[JessicaMeixner-NOAA]

Please add descriptions of the new terms to model/inp/ww3_grid.inp in the UNST namelist section: https://github.com/NOAA-EMC/WW3/blob/develop/model/inp/ww3_grid.inp#L318

[JessicaMeixner-NOAA]

@aronroland once this is done I can try to do some tests of this feature, but will need additional information before I can do so. We'll wait to run regression tests once we have testing information included in the PR. Lastly, you checked the box for "If a new feature was added, a regression test for testing the new feature is added", but I don't see the new regression test included yet, so we'll need that as well before this can be merged. That being said, as soon as I have enough information to run a test on my end I can do that.

[JessicaMeixner-NOAA]

Thanks for adding updates to ww3_grid.inp !

[aronroland]

Hi Jessica, as I see things we would like to proceed with the small global case. I have no time to work on the synthetic test case now but I promise to do that in the 2nd half of this year. We will inform u when the full pull request is ready for review. Cheers Aron From: Jessica Meixner ***@***.***> Sent: Mittwoch, 10. Januar 2024 17:33 To: NOAA-EMC/WW3 ***@***.***> Cc: Aron Roland ***@***.***>; Mention ***@***.***> Subject: Re: [NOAA-EMC/WW3] Ww3 gse2 (PR #1143) @JessicaMeixner-NOAA commented on this pull request.

_____ In model/src/w3gridmd.F90 <#1143 (comment)> :

JGS_BLOCK_GAUSS_SEIDEL = .TRUE.

JGS_USE_JACOBI = .TRUE. + JGS_LGSE = .FALSE. @aronroland <https://github.com/aronroland> once this is done I can try to do some tests of this feature, but will need additional information before I can do so. We'll wait to run regression tests once we have testing information included in the PR. Lastly, you checked the box for "If a new feature was added, a regression test for testing the new feature is added", but I don't see the new regression test included yet, so we'll need that as well before this can be merged. That being said, as soon as I have enough information to run a test on my end I can do that. — Reply to this email directly, view it on GitHub <#1143 (comment)> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB2S43WILPUJIW7KX2DFRELYN27FBAVCNFSM6AAAAABAXURM7OVHI2DSMVQWIX3LMV43YUDVNRWFEZLROVSXG5CSMV3GSZLXHMYTQMJTGYZTQMZZGY> . You are receiving this because you were mentioned. <https://github.com/notifications/beacon/AB2S43UE7EWZW6JFJJCQ4QTYN27FBA5CNFSM6AAAAABAXURM7OWGG33NNVSW45C7OR4XAZNRKB2WY3CSMVYXKZLTORJGK5TJMV32UY3PNVWWK3TUL5UWJTTMDHWPY.gif> Message ID: ***@***.*** ***@***.***> >