Fix interior obcs

[kshedstrom]

Just the non-rotational parts of PR #752 for now.

[Hallberg-NOAA]

There are a handful of issued related to the use of wide halos in the barotropic solver that will need to be addressed (see the detailed comments), but otherwise this PR is looking good to me.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 21.91%. Comparing base (bb66d8a) to head (0171c8d).

Files with missing lines	Patch %	Lines
src/core/MOM_open_boundary.F90	0.00%	8 Missing ⚠️

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HEAD has 1 upload less than BASE

Flag	BASE (bb66d8a)	HEAD (0171c8d)
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Additional details and impacted files

@@              Coverage Diff              @@
##           dev/gfdl     #814       +/-   ##
=============================================
- Coverage     38.15%   21.91%   -16.25%     
=============================================
  Files           296      136      -160     
  Lines         87322    32868    -54454     
  Branches      16303     5847    -10456     
=============================================
- Hits          33316     7202    -26114     
+ Misses        48012    25109    -22903     
+ Partials       5994      557     -5437     

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[kshedstrom]

Thanks for pointing out that the array needs wide halos. Hopefully this takes care of the problem - I don't have wide halo tests since they aren't compatible with OBCs.

[Hallberg-NOAA]

I am convinced that this revised PR is now correct as written.

The one point about this commit that is still troubling me is that some diagnostics are changing slightly, so this PR is tripping over the automated TC testing. Moreover there does not appear to be way to recover the previous answers. If we were to add a new runtime parameter (like EXTERIOR_OBC_BUG) and a logical bug-fix test (like changing line 4900 of MOM_barotropic.F90 to if (associated(OBC) .and. (CS%exterior_OBC_bug == .false.)) then and something similar at lines 652 and 1056 of MOM_tracer_advect.F90, and perhaps add some logical tests at about lines 5079-5080 of MOM_open_boundary.F90, could we recover the previous answers with the right run-time parameter settings?

If such adding the new runtime parameter did work recover the previous (incorrect?) answers, it would greatly ease my unease about bending the rules for our testing, and I would by very happy to accept this PR without reservations.

[kshedstrom]

Thank you for the suggestions! I will add the logic to the MASKING_DEPTH code if it fails the tc testing.

[Hallberg-NOAA]

With the recent changes to this PR, all of my previous concerns have been addressed.

[Hallberg-NOAA]

This PR has passed pipeline testing at https://gitlab.gfdl.noaa.gov/ogrp/mom6ci/MOM6/-/pipelines/26527 with the expected warnings about a new runtime parameter.