Updated CORRELATION algorithm

[arango]

The CORRELATION driver that computes the 4D-Var error covariance normalization coefficients is updated:

• The set-up in read_phypar.F was cleaned out, so only the input grid and initial conditions NetCDF are processed. The other input ROMS NetCDF files are ignored since they are not needed.

• The input parameter NTIMES was overwritten and set to 1 since this driver does not timestep the ROMS kernel. The computer was running out of memory when ADJUST_BOUNDARY, ADJUST_STFLUX, or ADJUST_WSTRESS was activated with very large NTIMES and small NOBC and NSFF.

We have a case with:

   NTIMES =  788400
     NOBC == 10
     NSFF == 10

So the internal parameter:

    Nbrec = 1 + ntime(ng)/Nobc(ng) = 78841

resulting in the following array been allocated as:

    t_obc(0:217, 40, 4, 78841, 2, 2)

which is huge, and we several similar arrays when ADJUST_BOUNDARY is activated. Warnings for such cases were added in read_phypar.F. It makes sense to make NTIMES=1 in this driver to avoid such problem in the future.

• Lots of warnings were added to get_state.F when the needed NetCDF variable is not founded in the input NetCDF file. For example, to process tangent linear model free-surface we have:

  !
  !  Read in tangent linear free-surface (m).
  !
          IF (get_var(idFsur)) THEN
            foundit=find_string(var_name, n_var, TRIM(Vname(1,idFsur)),   &
       &                        varid)
            IF (foundit) THEN
              gtype=var_flag(varid)*r2dvar
              status=nf_fread2d(ng, IDmod, ncname, ncINPid,               &
       &                        Vname(1,idFsur), varid,                   &
       &                        InpRec, gtype, Vsize,                     &
       &                        LBi, UBi, LBj, UBj,                       &
       &                        Fscl, Fmin, Fmax,                         &
  # ifdef MASKING
       &                        GRID(ng) % rmask,                         &
  # endif
       &                        OCEAN(ng) % tl_zeta(:,:,Tindex))
              IF (FoundError(status, nf90_noerr, __LINE__,                &
       &                     __FILE__)) THEN
                IF (Master) THEN
                  WRITE (stdout,60) string, TRIM(Vname(1,idFsur)),        &
       &                            InpRec, TRIM(ncname)
                END IF
                exit_flag=2
                ioerror=status
                RETURN
              ELSE
                IF (Master) THEN
                  WRITE (stdout,70) TRIM(Vname(2,idFsur)), Fmin, Fmax
                END IF
              END IF
            ELSE
              IF (Master) THEN
                WRITE (stdout,80) string, TRIM(Vname(1,idFsur)),          &
       &                          TRIM(ncname)
              END IF
              exit_flag=4
              IF (FoundError(exit_flag, nf90_noerr, __LINE__,             &
       &                     __FILE__)) THEN
                RETURN
              END IF
            END IF
          END IF
  

  so the new piece of code is after the ELSE statement if the variable is not found:

         IF (get_var(idFsur)) THEN
           ...
           IF (foundit) THEN
             ...
           ELSE
             IF (Master) THEN
               WRITE (stdout,80) string, TRIM(Vname(1,idFsur)),          &
      &                          TRIM(ncname)
             END IF
             exit_flag=4
             IF (FoundError(exit_flag, nf90_noerr, __LINE__,             &
      &                     __FILE__)) THEN
               RETURN
             END IF
           END IF
         END IF
  

Many thanks to Andy Moore for reporting some of these issues.