[BUG] derivation of thetaot300 and thetaot700

[YanchunHe]

Describe the bug
cite H.Pohlmann

I am trying to compare thetaot300 and thetaot700 for OHC between MPI-ESM1-2-LR and NorESM2-LM. I had expected the values to be similar to the SST data. However, the data from the NorESM2-LM model are mainly between -1 and 3 deg C. Are theses anomalies? Against which mean?

To Reproduce
...

Additional context
cite I.Bethke

I can confirm the problem and suspect a bug in the post-processing that vertically integrates. The code in question is https://github.com/NorESMhub/noresm2cmor/blob/master/source/m_modelsocn.F , lines 1517-1540:

c --- - Average over upper 300 m
        CASE ('dzavg300')
          fldtmp=1e20
          DO j=1,jj
            DO i=1,ii
              IF (fld(i,j,1).NE.1e20) THEN
                fldtmp(i,j,1)= (min(300.,pdepth(i,j),depth_bnds(2,1))
     .                         -min(300.,pdepth(i,j),depth_bnds(1,1)))
     .                         *pbot(i,j)/pdepth(i,j)
                fld(i,j,1)=fld(i,j,1)*fldtmp(i,j,1)
              END IF
              DO k=2,kk
                IF (fld(i,j,k).NE.1e20) THEN
                  fldtmp(i,j,k)= (min(300.,pdepth(i,j),depth_bnds(2,k))
     .                           -min(300.,pdepth(i,j),depth_bnds(1,k)))
     .                           *pbot(i,j)/pdepth(i,j)
                  fld(i,j,k)=fld(i,j,k-1)+fld(i,j,k)*fldtmp(i,j,k)
                  fldtmp(i,j,1)=fldtmp(i,j,1)+fldtmp(i,j,k)
                ENDIF
              ENDDO
              IF (fld(i,j,1).NE.1e20)
     .          fld(i,j,1)=fld(i,j,1)/fldtmp(i,j,1)
            ENDDO
          ENDDO  

! I think
                  fld(i,j,k)=fld(i,j,k-1)+fld(i,j,k)*fldtmp(i,j,k)
! needs to be changed to
                  fld(i,j,1)=fld(i,j,1)+fld(i,j,k)*fldtmp(i,j,k)

[YanchunHe]

@monsieuralok

Could you please retract all thetao300, thetao700 and thetao2000 for all model versions and experiments?