[0.25deg config] MINIMUM_DEPTH & MASKING_DEPTH in MOM_grid_init

[minghangli-uni]

[0.25deg config] MINIMUM_DEPTH & MASKING_DEPTH in MOM_grid_init

[minghangli-uni]

Sounds good. I'll update the PR and include a note about the modifications.

[aekiss]

Thanks for the detailed description @minghangli-uni.

To be pedantic, the min depth in the OM2 0.25° 50-level grid is actually 11.805749893188477 m - will that matter?

If this needs to match exactly, it seems like we should have an automatic way to set MINIMUM_DEPTH, so we don't need to remember to update it whenever we change the topography or number of depth levels.

[minghangli-uni]

Thank you for pointing this out @aekiss.

As long as MIN_DEPTH is between the MASKING_DEPTH=0.0 and the minimum depth (i.e., 11.805749893188477 m), the exact value of MIN_DEPTH is not critical.

[aekiss]

Yes, I was just about to post that :-)

So when we change to 75 levels we'll need to adjust MIN_DEPTH to suit the minimum we set in the updated topography.

[aekiss]

Actually, it would be simpler to set

MINIMUM_DEPTH = 0.0            !   [m] default = 0.0
                                ! If MASKING_DEPTH is unspecified, then anything shallower than MINIMUM_DEPTH is
                                ! assumed to be land and all fluxes are masked out. If MASKING_DEPTH is
                                ! specified, then all depths shallower than MINIMUM_DEPTH but deeper than
                                ! MASKING_DEPTH are rounded to MINIMUM_DEPTH.
MASKING_DEPTH = 0.0             !   [m] default = -9999.0
                                ! The depth below which to mask points as land points, for which all fluxes are
                                ! zeroed out. MASKING_DEPTH is ignored if it has the special default value.

and set the minimum depth when we generate topog.nc with topogtools min_max_depth, right?
I think that's what we meant in the namelist discussion.

[minghangli-uni]

Yes, I agree. Setting MINIMUM_DEPTH to 0.0 is simpler.

Bur it appears that if MASKING_DEPTH has its default value of -9999, it is automatically set to the same value as MINIMUM_DEPTH.

  if (mask_depth == -9999.*US%m_to_Z) mask_depth = min_depth

Since the default value of MINIMUM_DEPTH is 0, there is no need to configure these two parameters in the MOM_input.

[aekiss]

That would be even simpler, so I'm tempted to omit both parameters from MOM_input. Does that sound ok? MASKING_DEPTH = -9999 is the default, even though the comments say it's not the preferred approach.

[minghangli-uni]

ACCESS-NRI/access-om3-configs#78 is merged.