ssh=0 in the corners with BDY

[clem]

Context

I run a regional configuration with 4 boundaries using BDY (both in 3.6 stable and in the trunk) and I encounter a problem in the 4 corners of my domain: SSH=0 there while it should not be.

Analysis

The issue only occurs with BDY (a closed boundary simulation is OK)
It is not due to the tides (removed).
I checked the input files which are OK at the corners (SSH/=0).

Fix

Does anybody know where it can come from?

[clem]

In addition, I do not understand in the trunk the complexity of the subroutine bdy_ssh (in bdydyn2d.F90).

The following lines:

            zcoef1 = bdytmask(ii-1,ij  ) +  bdytmask(ii+1,ij  )
            zcoef2 = bdytmask(ii  ,ij-1) +  bdytmask(ii  ,ij+1)
            IF ( zcoef1+zcoef2 == 0 ) THEN
               ! corner
               zcoef = bdytmask(ii-1,ij) + bdytmask(ii+1,ij) +  bdytmask(ii,ij-1) +  bdytmask(ii,ij+1)
               zssh(ii,ij) = zssh(ii-1,ij  ) * bdytmask(ii-1,ij  ) + &
                 &           zssh(ii+1,ij  ) * bdytmask(ii+1,ij  ) + &
                 &           zssh(ii  ,ij-1) * bdytmask(ii  ,ij-1) + &
                 &           zssh(ii  ,ij+1) * bdytmask(ii  ,ij+1)
               zssh(ii,ij) = ( zssh(ii,ij) / MAX( 1, zcoef) ) * tmask(ii,ij,1)

Can be replaced by:

            zcoef = bdytmask(ii-1,ij) + bdytmask(ii+1,ij) +  bdytmask(ii,ij-1) +  bdytmask(ii,ij+1)
            IF ( zcoef == 0 ) THEN
               zssh(ii,ij) = 0._wp

Or do I miss something here?

[gmattia]

I’d suggest to simplify the subroutine bdy_ssh (bdydyn2d.F90 in the trunk) as it is done in 3.6 stable version.
In the 4 corners of domain SSH=0, it's no correct.
In subroutine bdy_ssh (in 3.6 stable version ), when zcoeff=0 zssh(ii,jj)=0, but I don't understand.

[gmattia]

In subroutine bdy_ssh (in 3.6 stable version ), when zcoeff=0 zssh(ii,jj)=0,
but I still do not understand the motivation.

[clevy]

The fix is now described in ticket 1997 and should be applied both on 3_6_STABLE, in the trunk and in devmerge_2017 branch

[clem]

fixed at r10518