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mom-ocean / MOM5

The Modular Ocean Model
https://mom-ocean.github.io/
GNU Lesser General Public License v3.0
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Fix submeso scale smoothing #264

Open aidanheerdegen opened 6 years ago

aidanheerdegen commented 6 years ago

Grid scale noise observed in the ACCESS-OM2 models (https://github.com/OceansAus/access-om2/issues/110) could be addressed if the smooth_hblt option was fixed.

!  <DATA NAME="smooth_hblt" TYPE="logical">
!  For smoothing on the submeso bldepth field. This is useful 
!  since the bldepth obtained from KPP or diagnosed mld can 
!  have some grid noise. 
!  Default smooth_hblt=.false. since this agrees with legacy.
!  Note that this scheme fails to reproduce across
!  processor layout, so it remains broken.  
!  </DATA>

https://github.com/mom-ocean/MOM5/blob/master/src/mom5/ocean_param/lateral/ocean_submesoscale.F90#L1330

russfiedler commented 6 years ago

To expand on this. It appears that the smoothing as it stands allows the the boundary layer depth to be smoothed to below the maximum depth of the water column if the surrounding values of hblt are large enough. It appears that subsequent code assumes that the value of hblt is sensible when calculating kblt etc. There should be a sanity check for the value, something like hblt=min(hblt,zbot) where zbot is the depth of the column.

StephenGriffies commented 6 years ago

I agree @russfiedler ; sanity check is needed.