Horizontal Velocity at the Bottom

[ezaron]

What version of the code are you using?
I'm using a recently checked-out branch, dev/gfdl, from GitHub - NOAA-GFDL/MOM6-examples: Example configurations for MOM6 and SIS2

Question:
What is the recommended method for computing and outputting the horizontal bottom current vector from MOM6?

I have looked through the diagnostics code and available_diagnostics file, and I don't see built-in method for outputting the bottom or near-bottom horizontal current vector.

I looked in the restart file, and it seems that the deepest layers have zero horizontal currents over much of the ocean (I am using ALE with 41 HYCOM-hybrid layers).

I tried to follow the code that computes taux_bot and tauy_bot. These seem to be computed from u(i,j,nz),v(i,j,nz) times a friction coefficient, but since the bottom velocity appears to be zero, I assume there are details here I don't understand, possibly related to the barotropic/baroclinic split.

-Ed

 

[kshedstrom@alaska_edu]

Those bottom zero velocities could be in density layers denser than you have at that location. You need to find the bottom physical layer. The variables tob and sob are temperature and salinity at the bottom of the water column, above the hidden (unused) layers. You can follow the code for producing them to add uob and vob.