!-------------------------------------- LICENCE BEGIN ------------------------------------
!Environment Canada - Atmospheric Science and Technology License/Disclaimer, 
!                     version 3; Last Modified: May 7, 2008.
!This is free but copyrighted software; you can use/redistribute/modify it under the terms 
!of the Environment Canada - Atmospheric Science and Technology License/Disclaimer 
!version 3 or (at your option) any later version that should be found at: 
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!
!This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
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!See the above mentioned License/Disclaimer for more details.
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!-------------------------------------- LICENCE END --------------------------------------
***s/r vzpng_zmean_ad - ADJ of vzpng_zmean 
*
#include "model_macros_f.h"
*

      subroutine vspng_zmean_ad( F_pert,F_field,tsum,DIST_DIM, Nk, lmean) 2
*
      implicit none
*
      integer DIST_DIM, Nk
      real F_field(DIST_SHAPE,Nk),F_pert(DIST_SHAPE,Nk),tsum(l_nj,Nk)
      logical lmean
*
*author 
*     M.Tanguay - rpn - december 2006
*     
*revision
*v3_30 - Tanguay M.      - initial MPI version 
*v3_31 - Tanguay M.      - up to date with respect to vspng_zmean   
*     
*object
*     see id section
*     
*implicits
#include "glb_ld.cdk"
*
      integer i,j,k
      integer i0,in,j0,jn,k0,kn,njk,err
      real*8 sum(l_nj,Nk),gsum(l_nj,Nk)
*
*--------------------------------------------------------------------
*
      i0 = 1
      in = l_ni
      j0 = 1
      jn = l_nj
      k0 = 1
      kn = Nk
      njk= l_nj*Nk
*
*     Zero adjoint variables
*     ----------------------
      sum  = 0.
      gsum = 0.
*
      if(lmean) then
*
!$omp parallel
!$omp do
         do k=kn,k0,-1
            do j=jn,j0,-1
               do i=in,i0,-1
                  tsum     (j,k) = - F_pert(i,j,k) + tsum     (j,k)
                  F_field(i,j,k) =   F_pert(i,j,k) + F_field(i,j,k)
                  F_pert (i,j,k) = 0.                  
               end do
            end do
         end do
!$omp enddo
!$omp end parallel
*
         gsum = tsum/dble(G_ni)+gsum
         tsum = 0.
*
         call rpn_comm_ALLREDUCE ( gsum, sum, l_nj*Nk,
     $                "MPI_DOUBLE_PRECISION","MPI_SUM","EW",err )
*
!$omp parallel 
!$omp do
         do k=kn,k0,-1
            do j=jn,j0,-1
               do i=in,i0,-1
                  F_field(i,j,k) = real(sum(j,k)) + F_field(i,j,k)
               end do
               sum(j,k) = 0.
            end do
         end do
!$omp enddo
!$omp end parallel
*
      else
*
!$omp parallel
!$omp do
         do k=kn,k0,-1
            do j=jn,j0,-1
               do i=in,i0,-1
                  tsum     (j,k) = F_pert(i,j,k) + tsum     (j,k)
                  F_field(i,j,k) = F_pert(i,j,k) + F_field(i,j,k)
                  F_pert (i,j,k) = 0.                  
               end do
            end do
         end do
!$omp enddo
!$omp end parallel
      endif
*
*----------------------------------------------------------------
*
      return
      end subroutine vspng_zmean_ad