Problem with ST4 SDSBCHOICE=2

[benoitp-cmc]

Describe the bug I have a Great Lakes case where I run with T500. It used to produce a reasonnable wave forecast, following #189 the forecast is much slower (more than 6 times) and produces Hs up to 125 m.

To Reproduce Try a run with T500 parameters

• Before 189: SDSC1=1, SDSBCK=0.185, etc.
• After 189: SDSBCHOICE=2, SDSBCK=0.185, etc.

Expected behavior Same behaviour as before #189. Not 125 m wave heights.

Additional context

• With T500 (SDSC1=1, SDSBCK=0.185), the T441/Ardhuin et al. if would be true and so would be the T500/Filipot et al. if. The second if depends on the PB value defined in the first if.
• The second to last line of T500/Filipot et al PB = (1-SSDSC(1))*PB2*A + SSDSC(1)*PB no longer works now that SDSBCHOICE uses SSDSC(1) and must be 2 in this context rather than a namelist option (1 for T500).
• tp1.8. is the only regression test for SDSBCHOICE=2. It only runs for a minute and no wind input which is probably why it gave sensible results.

/cc @mickaelaccensi

[mickaelaccensi]

Hi Benoit, Can you try with this branch: https://github.com/umr-lops/WW3/tree/feature/ST4table

If the issue is still here, I'll see with Fabrice to add a bugfix in this branch

Mickael

[benoitp-cmc]

It did not compile (Intel).

.../model/src/w3gdatmd.F90(2639): error #6460: This is not a component name that is defined in the encompassing structure.   [SINTAILPAR]
    SINTAILPAR  => MPARS(IMOD)%SRCPS%SINTAILPAR
-------------------------------------^
.../model/src/w3gdatmd.F90(2639): error #6794: The rank of the target is different from the pointer.   [SINTAILPAR]
    SINTAILPAR  => MPARS(IMOD)%SRCPS%SINTAILPAR
----^
.../model/src/w3gdatmd.F90(2639): error #6795: The target must be of the same type and kind type parameters as the pointer.   [SINTAILPAR]
    SINTAILPAR  => MPARS(IMOD)%SRCPS%SINTAILPAR
----^

I don't understand all the changes in this branch but it doesn't look like they would adress the first two bullets I mention in "Additional context".

[benoitp-cmc]

What I think is needed is changes similar to this: https://github.com/eccc-waves/WW3/tree/bugfix/sdsbchoice2

With this branch, I no longer get 120 m Hs. But it's not right yet, I get Hs that are ~40% higher than with the old T500.

[ardhuin]

Hello ...I'll have to check a few things on what I've changed that could affect the tail of the spectrum. It almost sounds like dissipation is zero... It is easy to use ts1.1 to check for these kind of things. thanks for spotting this issue.

[benoitp-cmc]

Merci d'y jeter un coup d'oeil.

With SSDSC(1)=2 and PB=0, the calculation of PB = (1-SSDSC(1))*PB2*A + SSDSC(1)*PB, likely gives a negative probability of breaking.

Once the wind starts, the energy accumulates very rapidly with only episodical dissipation until Hs reaches a fixed height. The pattern of max Hs seems to match bathymetry pretty closely, up to a point.

Signficant wave height (m) after 24 hours from cold start (similar to 6 hours except in some isolated corners)

Bathymetry (m)

[ardhuin]

OK, there was one line missing in the code, and the dissipation was effectively zero. basically in w3src4md.F90 we need to have SRHS = DDIAG * A just before ! CASE(3) I've just added this and an option in ww3_ts1 to test this T500 setting (this is in a local ST4 branch). Mickael should be pushing this through shortly.

[benoitp-cmc]

I will test next week.

[benoitp-cmc]

Adding SRHS = DDIAG * A helped. On its own the result is still pretty far (~50% too high). Along with a476ee83658dfc414a68d55dcd83a9d161858c94 and d73e29566468ebac9448aba29bdec249a3a4fcc8 the results are pretty close but still about 10% higher than before #189. I'll try ww3_ts1.

[ardhuin]

OK. I will have to dig deeper and check all the parameters ...

Adding SRHS = DDIAG * A helped. On its own the result is still pretty far (~50% too high). Along with a476ee8 [1] and d73e295 [2] the results are pretty close but still about 10% higher than before #189 [3]. I'll try ww3_ts1.

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Links:

[1] https://github.com/NOAA-EMC/WW3/commit/a476ee83658dfc414a68d55dcd83a9d161858c94 [2] https://github.com/NOAA-EMC/WW3/commit/d73e29566468ebac9448aba29bdec249a3a4fcc8 [3] https://github.com/NOAA-EMC/WW3/pull/189 [4] https://github.com/NOAA-EMC/WW3/issues/1074#issuecomment-1756378773 [5] https://github.com/notifications/unsubscribe-auth/AG4TOHXBFQWKP2ASUQ2WZUTX6XFW3AVCNFSM6AAAAAA42KMQTSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTONJWGM3TQNZXGM

-- Fabrice Ardhuin Laboratoire d'Océanographie Physique et Spatiale, Brest, France Phone: (33) 6 52 86 64 41 -- Groupe de recherche sur les états de mer: http://wwz.ifremer.fr/iowaga