#include "cppdefs.h"
      MODULE nf_fread4d_mod
!
!svn $Id$
!================================================== Hernan G. Arango ===
!  Copyright (c) 2002-2020 The ROMS/TOMS Group                         !
!    Licensed under a MIT/X style license                              !
!    See License_ROMS.txt                                              !
!=======================================================================
!                                                                      !
!  This function reads in a generic floating point 4D array from an    !
!  input NetCDF file.                                                  !
!                                                                      !
!  On Input:                                                           !
!                                                                      !
!     ng         Nested grid number (integer)                          !
!     model      Calling model identifier (integer)                    !
!     ncname     NetCDF file name (string)                             !
!     ncid       NetCDF file ID (integer)                              !
!     ncvname    NetCDF variable name (string)                         !
!     ncvarid    NetCDF variable ID (integer)                          !
!     tindex     NetCDF time record index to read (integer)            !
!     gtype      C-grid type (integer)                                 !
!     Vsize      Variable dimensions in NetCDF file (integer 1D array) !
!     LBi        I-dimension Lower bound (integer)                     !
!     UBi        I-dimension Upper bound (integer)                     !
!     LBj        J-dimension Lower bound (integer)                     !
!     UBj        J-dimension Upper bound (integer)                     !
!     LBk        K-dimension Lower bound (integer)                     !
!     UBk        K-dimension Upper bound (integer)                     !
!     LBt        Time-dimension Lower bound (integer)                  !
!     UBt        Time-dimension Upper bound (integer)                  !
!     Ascl       Factor to scale field after reading (real).           !
!     Amask      Land/Sea mask, if any (real 4D array)                 !
!                                                                      !
!  On Output:                                                          !
!                                                                      !
!     Amin       Field minimum value (real)                            !
!     Amax       Field maximum value (real)                            !
!     A          Field to read in (real 4D array)                      !
!     nf_fread4d Error flag (integer)                                  !
!                                                                      !
!=======================================================================
!
      implicit none

      CONTAINS

#if defined PARALLEL_IN && defined DISTRIBUTE
!
!***********************************************************************
      FUNCTION nf_fread4d (ng, model, ncname, ncid,                     &
     &                     ncvname, ncvarid,                            &
     &                     tindex, gtype, Vsize,                        &
     &                     LBi, UBi, LBj, UBj, LBk, UBk, LBt, UBt,      &
     &                     Ascl, Amin, Amax,                            &
# ifdef MASKING
     &                     Amask,                                       &
# endif
     &                     A)
!***********************************************************************
!
      USE mod_param
      USE mod_parallel
      USE mod_iounits
      USE mod_ncparam
      USE mod_netcdf
      USE mod_scalars
!
      USE distribute_mod, ONLY : mp_bcasti, mp_reduce
# if defined MASKING && defined READ_WATER
      USE distribute_mod, ONLY : mp_collect
# endif
      USE strings_mod,    ONLY : FoundError
!
      implicit none
!
!  Imported variable declarations.
!
      integer, intent(in) :: ng, model, ncid, ncvarid, tindex, gtype
      integer, intent(in) :: LBi, UBi, LBj, UBj, LBk, UBk, LBt, UBt
      integer, intent(in) :: Vsize(4)

      real(dp), intent(in)  :: Ascl
      real(r8), intent(out) :: Amin
      real(r8), intent(out) :: Amax

      character (len=*), intent(in) :: ncname
      character (len=*), intent(in) :: ncvname

# ifdef ASSUMED_SHAPE
#  ifdef MASKING
      real(r8), intent(in) :: Amask(LBi:,LBj:)
#  endif
      real(r8), intent(out) :: A(LBi:,LBj:,LBk:,LBt:)
# else
#  ifdef MASKING
      real(r8), intent(in) :: Amask(LBi:UBi,LBj:UBj)
#  endif
      real(r8), intent(out) :: A(LBi:UBi,LBj:UBj,LBk:UBk,LBt:UBt)
# endif
!
!  Local variable declarations.
!
      logical, dimension(3) :: foundit

      integer :: i, ic, ij, j, jc, k, kc, l, lc, np, Npts
      integer :: Imin, Imax, Isize, Jmin, Jmax, Jsize, IJsize
      integer :: Istr, Iend
      integer :: Ioff, Joff, Koff, Loff
      integer :: Ilen, Jlen, Klen, Llen, IJlen
      integer :: Cgrid, MyType, ghost, status, wtype

      integer, dimension(5) :: start, total

      integer :: nf_fread4d

      real(r8) :: Afactor, Aoffset, Aspval

      real(r8), parameter :: IniVal= 0.0_r8

      real(r8), dimension(2) :: buffer
      real(r8), dimension(3) :: AttValue

# if defined MASKING && defined READ_WATER
      real(r8), allocatable :: A2d(:)
# endif
      real(r8), allocatable :: wrk(:)

      character (len= 3), dimension(2) :: op_handle
      character (len=12), dimension(3) :: AttName
!
!-----------------------------------------------------------------------
!  Set starting and ending indices to process.
!-----------------------------------------------------------------------
!
!  Set first and last grid point according to staggered C-grid
!  classification. Set the offsets for variables with starting
!  zero-index.  Recall the NetCDF does not support a zero-index.
!
!  Notice that (Imin,Jmin) and (Imax,Jmax) are the corner of the
!  computational tile. If ghost=0, ghost points are not processed.
!  They will be processed elsewhere by the appropriate call to any
!  of the routines in "mp_exchange.F".  If ghost=1, the ghost points
!  are read.
!
# ifdef NO_READ_GHOST
      ghost=0                        ! non-overlapping, no ghost points
# else
      IF (model.eq.iADM) THEN
        ghost=0                      ! non-overlapping, no ghost points
      ELSE
        ghost=1                      ! overlapping, read ghost points
      END IF
# endif

      MyType=gtype

      SELECT CASE (ABS(MyType))
        CASE (p2dvar, p3dvar)
          Cgrid=1
          Isize=IOBOUNDS(ng)%xi_psi
          Jsize=IOBOUNDS(ng)%eta_psi
        CASE (r2dvar, r3dvar, w3dvar)
          Cgrid=2
          Isize=IOBOUNDS(ng)%xi_rho
          Jsize=IOBOUNDS(ng)%eta_rho
        CASE (u2dvar, u3dvar)
          Cgrid=3
          Isize=IOBOUNDS(ng)%xi_u
          Jsize=IOBOUNDS(ng)%eta_u
        CASE (v2dvar, v3dvar)
          Cgrid=4
          Isize=IOBOUNDS(ng)%xi_v
          Jsize=IOBOUNDS(ng)%eta_v
        CASE DEFAULT
          Cgrid=2
          Isize=IOBOUNDS(ng)%xi_rho
          Jsize=IOBOUNDS(ng)%eta_rho
      END SELECT

      Imin=BOUNDS(ng)%Imin(Cgrid,ghost,MyRank)
      Imax=BOUNDS(ng)%Imax(Cgrid,ghost,MyRank)
      Jmin=BOUNDS(ng)%Jmin(Cgrid,ghost,MyRank)
      Jmax=BOUNDS(ng)%Jmax(Cgrid,ghost,MyRank)

      Ilen=Imax-Imin+1
      Jlen=Jmax-Jmin+1
      Klen=UBk-LBk+1
      Llen=UBt-LBt+1
!
!  Check if the following attributes: "scale_factor", "add_offset", and
!  "_FillValue" are present in the input NetCDF variable:
!
!  If the "scale_value" attribute is present, the data is multiplied by
!  this factor after reading.
!  If the "add_offset" attribute is present, this value is added to the
!  data after reading.
!  If both "scale_factor" and "add_offset" attributes are present, the
!  data are first scaled before the offset is added.
!  If the "_FillValue" attribute is present, the data having this value
!  is treated as missing and it is replaced with zero. This feature it
!  is usually related with the land/sea masking.
!
      AttName(1)='scale_factor'
      AttName(2)='add_offset  '
      AttName(3)='_FillValue  '

      CALL netcdf_get_fatt (ng, model, ncname, ncvarid, AttName,        &
     &                      AttValue, foundit,                          &
     &                      ncid = ncid)
      IF (FoundError(exit_flag, NoError, __LINE__,                      &
     &               __FILE__)) THEN
        nf_fread4d=ioerror
        RETURN
      END IF

      IF (.not.foundit(1)) THEN
        Afactor=1.0_r8
      ELSE
        Afactor=AttValue(1)
      END IF

      IF (.not.foundit(2)) THEN
        Aoffset=0.0_r8
      ELSE
        Aoffset=AttValue(2)
      END IF

      IF (.not.foundit(3)) THEN
        Aspval=spval_check
      ELSE
        Aspval=AttValue(3)
      END IF
!
!-----------------------------------------------------------------------
!  Parallel I/O: Read in tile data from requested field and scale it.
!                Processing both water and land points.
!-----------------------------------------------------------------------
!
      IF (gtype.gt.0) THEN
!
!  Set offsets due the NetCDF dimensions. Recall that some output
!  variables not always start at one.
!
        SELECT CASE (ABS(MyType))
          CASE (p2dvar, p3dvar)
            Ioff=0
            Joff=0
          CASE (r2dvar, r3dvar, w3dvar)
            Ioff=1
            Joff=1
          CASE (u2dvar, u3dvar)
            Ioff=0
            Joff=1
          CASE (v2dvar, v3dvar)
            Ioff=1
            Joff=0
          CASE DEFAULT
            Ioff=1
            Joff=1
        END SELECT

        IF (LBk.eq.0) THEN
          Koff=1
        ELSE
          Koff=0
        END IF

        IF (LBt.eq.0) THEN
          Loff=1
        ELSE
          Loff=0
        END IF

        Npts=Ilen*Jlen*Klen*Llen
!
!  Allocate scratch work array.
!
        IF (.not.allocated(wrk)) THEN
          allocate ( wrk(Npts) )
          wrk=0.0_r8
        END IF
!
!  Read in data: all parallel nodes read their own tile data.
!
        start(1)=Imin+Ioff
        total(1)=Ilen
        start(2)=Jmin+Joff
        total(2)=Jlen
        start(3)=LBk+Koff
        total(3)=Klen
        start(4)=LBt+Loff
        total(4)=Llen
        start(5)=tindex
        total(5)=1

        status=nf90_get_var(ncid, ncvarid, wrk, start, total)
        nf_fread4d=status
!
!  Scale read data and process fill values, if any.  Compute minimum
!  and maximum values.
!
        IF (status.eq.nf90_noerr) THEN
          Amin=spval
          Amax=-spval
          DO i=1,Npts
            IF (ABS(wrk(i)).ge.ABS(Aspval)) THEN
              wrk(i)=0.0_r8                   ! masked with _FillValue
            ELSE
              wrk(i)=Ascl*(Afactor*wrk(i)+Aoffset)
              Amin=MIN(Amin,wrk(i))
              Amax=MAX(Amax,wrk(i))
            END IF
          END DO
!
!  Set minimum and maximum values: global reduction.
!
          buffer(1)=Amin
          op_handle(1)='MIN'
          buffer(2)=Amax
          op_handle(2)='MAX'
          CALL mp_reduce (ng, model, 2, buffer, op_handle)
          Amin=buffer(1)
          Amax=buffer(2)
!
!  Unpack read data.
!
          ic=0
          DO l=LBt,UBt
            DO k=LBk,UBk
              DO j=Jmin,Jmax
                DO i=Imin,Imax
                  ic=ic+1
                  A(i,j,k,l)=wrk(ic)
                END DO
              END DO
            END DO
          END DO
        ELSE
          exit_flag=2
          ioerror=status
        END IF
      END IF

# if defined MASKING && defined READ_WATER
!
!-----------------------------------------------------------------------
!  Parallel I/O: Read in tile data from requested field and scale it.
!                Processing water points only.
!-----------------------------------------------------------------------
!
      IF (gtype.lt.0) THEN
!
!  Set number of points to process, grid type switch, and offsets due
!  array packing into 1D array in column-major order.
!
        SELECT CASE (ABS(MyType))
          CASE (p3dvar)
            IJlen=IOBOUNDS(ng)%xy_psi
            wtype=p2dvar
            Ioff=0
            Joff=1
          CASE (r3dvar, w3dvar)
            IJlen=IOBOUNDS(ng)%xy_rho
            wtype=r2dvar
            Ioff=1
            Joff=0
          CASE (u3dvar)
            IJlen=IOBOUNDS(ng)%xy_u
            wtype=u2dvar
            Ioff=0
            Joff=0
          CASE (v3dvar)
            IJlen=IOBOUNDS(ng)%xy_v
            wtype=v2dvar
            Ioff=1
            Joff=1
          CASE DEFAULT
            IJlen=IOBOUNDS(ng)%xy_rho
            wtype=r2dvar
            Ioff=1
            Joff=0
        END SELECT

        IF (LBk.eq.0) THEN
          Koff=0
        ELSE
          Koff=1
        END IF

        IF (LBt.eq.0) THEN
          Loff=1
        ELSE
          Loff=0
        END IF

        Npts=IJlen*Klen*Llen
        IJsize=Isize*Jsize
!
!  Allocate scratch work arrays.
!
        IF (.not.allocated(A2d)) THEN
          allocate ( A2d(IJsize) )
        END IF
        IF (.not.allocated(wrk)) THEN
          allocate ( wrk(Npts) )
          wrk=IniVal
        END IF
!
!  Read in data: all parallel nodes read a segment of the 1D data.
!  Recall that water points are pack in the NetCDF file in a single
!  dimension.
!
        CALL tile_bounds_1d (ng, MyRank, Npts, Istr, Iend)

        start(1)=Istr
        total(1)=Iend-Istr+1
        start(2)=1
        total(2)=tindex

        status=nf90_get_var(ncid, ncvarid, wrk(Istr:), start, total)
        nf_fread4d=status
!
!  Global reduction of work array.  We need this because the packing
!  of the water point only affects the model tile partition.
!
        IF (status.eq.nf90_noerr) THEN
          CALL mp_collect (ng, model, Npts, IniVal, wrk)
!
!  Scale read data and process fill values, if any.  Compute minimum
!  and maximum values.
!
          Amin=spval
          Amax=-spval
          DO i=1,Npts
            IF (ABS(wrk(i)).ge.ABS(Aspval)) THEN
              wrk(i)=0.0_r8             ! set _FillValue to zero
            ELSE
              wrk(i)=Ascl*(Afactor*wrk(i)+Aoffset)
              Amin=MIN(Amin,wrk(i))
              Amax=MAX(Amax,wrk(i))
            END IF
          END DO
!
!  Unpack read data.  This is tricky in parallel I/O.  The cheapeast
!  thing to do is reconstruct a packed 2D global array and then select
!  the appropriate values for the tile.
!
          DO l=LBt,UBt
            lc=(l-Loff)*IJlen*Klen
            DO k=LBk,UBk
              kc=(k-Koff)*IJlen+lc
              A2d=IniVal
              DO np=1,IJlen
                ij=SCALARS(ng)%IJwater(np,wtype)
                A2d(ij)=wrk(np+kc)
              END DO
              DO j=Jmin,Jmax
                jc=(j-Joff)*Isize
                DO i=Imin,Imax
                  ij=i+Ioff+jc
                  A(i,j,k,l)=A2d(ij)
                END DO
              END DO
            END DO
          END DO
        ELSE
          exit_flag=2
          ioerror=status
        END IF
      END IF
# endif
!
!-----------------------------------------------------------------------
!  Deallocate scratch work vector.
!-----------------------------------------------------------------------
!
# if defined MASKING && defined READ_WATER
      IF (allocated(A2d)) THEN
        deallocate (A2d)
      END IF
# endif

      IF (allocated(wrk)) THEN
        deallocate (wrk)
      END IF

      RETURN
      END FUNCTION nf_fread4d

#else

!
!***********************************************************************
      FUNCTION nf_fread4d (ng, model, ncname, ncid,                     &
     &                     ncvname, ncvarid,                            &
     &                     tindex, gtype, Vsize,                        &
     &                     LBi, UBi, LBj, UBj, LBk, UBk, LBt, UBt,      &
     &                     Ascl, Amin, Amax,                            &
# ifdef MASKING
     &                     Amask,                                       &
# endif
     &                     A)
!***********************************************************************
!
      USE mod_param
      USE mod_parallel
      USE mod_iounits
      USE mod_ncparam
      USE mod_netcdf
      USE mod_scalars
!
# ifdef DISTRIBUTE
      USE distribute_mod, ONLY : mp_bcasti
#  ifdef INLINE_2DIO
      USE distribute_mod, ONLY : mp_scatter2d
#  else
      USE distribute_mod, ONLY : mp_scatter3d
#  endif

# endif
      USE strings_mod,    ONLY : FoundError
!
      implicit none
!
!  Imported variable declarations.
!
      integer, intent(in) :: ng, model, ncid, ncvarid, tindex, gtype
      integer, intent(in) :: LBi, UBi, LBj, UBj, LBk, UBk, LBt, UBt
      integer, intent(in) :: Vsize(4)

      real(dp), intent(in)  :: Ascl
      real(r8), intent(out) :: Amin
      real(r8), intent(out) :: Amax

      character (len=*), intent(in) :: ncname
      character (len=*), intent(in) :: ncvname

# ifdef ASSUMED_SHAPE
#  ifdef MASKING
      real(r8), intent(in) :: Amask(LBi:,LBj:)
#  endif
      real(r8), intent(out) :: A(LBi:,LBj:,LBk:,LBt:)
# else
#  ifdef MASKING
      real(r8), intent(in) :: Amask(LBi:UBi,LBj:UBj)
#  endif
      real(r8), intent(out) :: A(LBi:UBi,LBj:UBj,LBk:UBk,LBt:UBt)
# endif
!
!  Local variable declarations.
!
      logical, dimension(3) :: foundit

      integer :: i, j, k, ic, fourth, Npts, NWpts, status, wtype
      integer :: Imin, Imax, Jmin, Jmax, Koff, Loff
      integer :: Ilen, Jlen, Klen, IJlen, MyType
# ifdef DISTRIBUTE
      integer :: Nghost
# endif
      integer, dimension(5) :: start, total

      integer :: nf_fread4d

      real(r8) :: Afactor, Aoffset, Aspval

      real(r8), dimension(3) :: AttValue

# if defined INLINE_2DIO && defined DISTRIBUTE
      real(r8), dimension(2+(Lm(ng)+2)*(Mm(ng)+2)) :: wrk
# else
      real(r8), dimension(2+(Lm(ng)+2)*(Mm(ng)+2)*(UBk-LBk+1)) :: wrk
# endif

      character (len=12), dimension(3) :: AttName
!
!-----------------------------------------------------------------------
!  Set starting and ending indices to process.
!-----------------------------------------------------------------------
!
!  Set first and last grid point according to staggered C-grid
!  classification. Set loops offsets.
!
      MyType=gtype

      SELECT CASE (ABS(MyType))
        CASE (p2dvar, p3dvar)
          Imin=IOBOUNDS(ng)%ILB_psi
          Imax=IOBOUNDS(ng)%IUB_psi
          Jmin=IOBOUNDS(ng)%JLB_psi
          Jmax=IOBOUNDS(ng)%JUB_psi
        CASE (r2dvar, r3dvar, w3dvar)
          Imin=IOBOUNDS(ng)%ILB_rho
          Imax=IOBOUNDS(ng)%IUB_rho
          Jmin=IOBOUNDS(ng)%JLB_rho
          Jmax=IOBOUNDS(ng)%JUB_rho
        CASE (u2dvar, u3dvar)
          Imin=IOBOUNDS(ng)%ILB_u
          Imax=IOBOUNDS(ng)%IUB_u
          Jmin=IOBOUNDS(ng)%JLB_u
          Jmax=IOBOUNDS(ng)%JUB_u
        CASE (v2dvar, v3dvar)
          Imin=IOBOUNDS(ng)%ILB_v
          Imax=IOBOUNDS(ng)%IUB_v
          Jmin=IOBOUNDS(ng)%JLB_v
          Jmax=IOBOUNDS(ng)%JUB_v
        CASE DEFAULT
          Imin=IOBOUNDS(ng)%ILB_rho
          Imax=IOBOUNDS(ng)%IUB_rho
          Jmin=IOBOUNDS(ng)%JLB_rho
          Jmax=IOBOUNDS(ng)%JUB_rho
      END SELECT

      Ilen=Imax-Imin+1
      Jlen=Jmax-Jmin+1
      Klen=UBk-LBk+1
      IJlen=Ilen*Jlen

#ifdef INLINE_2DIO
      IF (LBk.eq.0) THEN
        Koff=0
      ELSE
        Koff=1
      END IF
#endif

      IF (LBt.eq.0) THEN
        Loff=1
      ELSE
        Loff=0
      END IF
!
!  Check if the following attributes: "scale_factor", "add_offset", and
!  "_FillValue" are present in the input NetCDF variable:
!
!  If the "scale_value" attribute is present, the data is multiplied by
!  this factor after reading.
!  If the "add_offset" attribute is present, this value is added to the
!  data after reading.
!  If both "scale_factor" and "add_offset" attributes are present, the
!  data are first scaled before the offset is added.
!  If the "_FillValue" attribute is present, the data having this value
!  is treated as missing and it is replaced with zero. This feature it
!  is usually related with the land/sea masking.
!
      AttName(1)='scale_factor'
      AttName(2)='add_offset  '
      AttName(3)='_FillValue  '

      CALL netcdf_get_fatt (ng, model, ncname, ncvarid, AttName,        &
     &                      AttValue, foundit,                          &
     &                      ncid = ncid)
      IF (FoundError(exit_flag, NoError, __LINE__,                      &
     &               __FILE__)) THEN
        nf_fread4d=ioerror
        RETURN
      END IF

      IF (.not.foundit(1)) THEN
        Afactor=1.0_r8
      ELSE
        Afactor=AttValue(1)
      END IF

      IF (.not.foundit(2)) THEN
        Aoffset=0.0_r8
      ELSE
        Aoffset=AttValue(2)
      END IF

      IF (.not.foundit(3)) THEN
        Aspval=spval_check
      ELSE
        Aspval=AttValue(3)
      END IF

# ifdef DISTRIBUTE
!
!  Set the number of tile ghost points, Nghost, to scatter in
!  distributed-memory applications. If Nghost=0, the ghost points
!  are not processed.  They will be processed elsewhere by the
!  appropriate call to any of the routines in "mp_exchange.F".
!
#  ifdef NO_READ_GHOST
      Nghost=0
#  else
      IF (model.eq.iADM) THEN
        Nghost=0
      ELSE
        Nghost=NghostPoints
      END IF
#  endif
# endif
# if defined READ_WATER && defined MASKING
!
!  If processing water points only, set number of points and type
!  switch.
!
      SELECT CASE (ABS(MyType))
        CASE (p3dvar)
          Npts=IOBOUNDS(ng)%xy_psi
          wtype=p2dvar
        CASE (r3dvar, w3dvar)
          Npts=IOBOUNDS(ng)%xy_rho
          wtype=r2dvar
        CASE (u3dvar)
          Npts=IOBOUNDS(ng)%xy_u
          wtype=u2dvar
        CASE (v3dvar)
          Npts=IOBOUNDS(ng)%xy_v
          wtype=v2dvar
        CASE DEFAULT
          Npts=IOBOUNDS(ng)%xy_rho
          wtype=r2dvar
      END SELECT
      NWpts=(Lm(ng)+2)*(Mm(ng)+2)
#  if !(defined INLINE_2DIO && defined DISTRIBUTE)
      Npts=Npts*Klen
#  endif
# endif
!
!  Initialize local array to avoid denormalized numbers. This
!  facilitates processing and debugging.
!
      wrk=0.0_r8
!
!-----------------------------------------------------------------------
!  Serial I/O: Read in requested field and scale it.
!-----------------------------------------------------------------------
!
!  Proccess data as 3D slides.
!
      Amin=spval
      Amax=-spval

      DO fourth=LBt,UBt
        IF (MyType.gt.0) THEN
          start(1)=1
          total(1)=Ilen
          start(2)=1
          total(2)=Jlen
          start(3)=1
          total(3)=Klen
          start(4)=fourth+Loff
          total(4)=1
          start(5)=tindex
          total(5)=1
          Npts=IJlen
# if !(defined INLINE_2DIO && defined DISTRIBUTE)
          Npts=Npts*Klen
# endif
# if defined READ_WATER && defined MASKING
        ELSE
          start(1)=1+(fourth+Loff-1)*Npts
          total(1)=Npts
          start(2)=1
          total(2)=tindex
# endif
        END IF
# if defined INLINE_2DIO && defined DISTRIBUTE
!
!  Process data as 2D slices (level by level) to reduce memory
!  requirements.
!
      DO k=LBk,UBk
        start(3)=k-Koff+1
        total(3)=1
# endif
        status=nf90_noerr
        IF (InpThread) THEN
          status=nf90_get_var(ncid, ncvarid, wrk, start, total)
          IF (status.eq.nf90_noerr) THEN
            DO i=1,Npts
              IF (ABS(wrk(i)).ge.ABS(Aspval)) THEN
                wrk(i)=0.0_r8                 ! masked with _FillValue
              ELSE
                wrk(i)=Ascl*(Afactor*wrk(i)+Aoffset)
                Amin=MIN(Amin,wrk(i))
                Amax=MAX(Amax,wrk(i))
              END IF
            END DO
          END IF
        END IF
# ifdef DISTRIBUTE
        CALL mp_bcasti (ng, model, status)
# endif
        IF (FoundError(status, nf90_noerr, __LINE__,                    &
     &                 __FILE__)) THEN
          exit_flag=2
          ioerror=status
          nf_fread4d=status
          RETURN
        END IF
!
!-----------------------------------------------------------------------
!  Serial I/O: Unpack read field.
!-----------------------------------------------------------------------
!
# ifdef DISTRIBUTE
#  ifdef INLINE_2DIO
        CALL mp_scatter2d (ng, model, LBi, UBi, LBj, UBj,               &
     &                     Nghost, MyType, Amin, Amax,                  &
#   if defined READ_WATER && defined MASKING
     &                     NWpts, SCALARS(ng)%IJwater(:,wtype),         &
#   endif
     &                     Npts, wrk, A(:,:,k,fourth))
      END DO
#  else
        CALL mp_scatter3d (ng, model, LBi, UBi, LBj, UBj, LBk, UBk,     &
     &                     Nghost, MyType, Amin, Amax,                  &
#   if defined READ_WATER && defined MASKING
     &                     NWpts, SCALARS(ng)%IJwater(:,wtype),         &
#   endif
     &                     Npts, wrk, A(:,:,:,fourth))
#  endif
# else
        IF (MyType.gt.0) THEN
          ic=0
          DO k=LBk,UBk
            DO j=Jmin,Jmax
              DO i=Imin,Imax
                ic=ic+1
                A(i,j,k,fourth)=wrk(ic)
              END DO
            END DO
          END DO
#  if defined MASKING || defined READ_WATER
        ELSE
          ic=0
          DO k=LBk,UBk
            DO j=Jmin,Jmax
              DO i=Imin,Imax
                IF (Amask(i,j).gt.0.0_r8) THEN
                  ic=ic+1
                  A(i,j,k,fourth)=wrk(ic)
                ELSE
                  A(i,j,k,fourth)=0.0_r8
                END IF
              END DO
            END DO
          END DO
#  endif
        END IF
# endif
      END DO

      nf_fread4d=status

      RETURN
      END FUNCTION nf_fread4d
#endif
      END MODULE nf_fread4d_mod
