MODULE advec_s_pw_mod

!------------------------------------------------------------------------------!
! Current revisions:
! -----------------
!
!
! Former revisions:
! -----------------
! $Id: advec_s_pw.f90 1011 2012-09-20 08:15:29Z suehring $
!
! 1010 2012-09-20 07:59:54Z raasch
! cpp switch __nopointer added for pointer free version
!
! 19 2007-02-23 04:53:48Z raasch
! Calculation extended for gridpoint nzt
!
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.12  2006/02/23 09:42:55  raasch
! nzb_2d replaced by nzb_s_inner
!
! Revision 1.1  1997/08/29 08:54:20  raasch
! Initial revision
!
!
! Description:
! ------------
! Advection term for scalar variables using the Piacsek and Williams scheme
! (form C3). Contrary to PW itself, for reasons of accuracy their scheme is
! slightly modified as follows: the values of those scalars that are used for
! the computation of the flux divergence are reduced by the value of the
! relevant scalar at the location where the difference is computed (sk(k,j,i)).
! NOTE: at the first grid point above the surface computation still takes place!
!------------------------------------------------------------------------------!

    PRIVATE
    PUBLIC advec_s_pw

    INTERFACE advec_s_pw
       MODULE PROCEDURE advec_s_pw
       MODULE PROCEDURE advec_s_pw_ij
    END INTERFACE
 
 CONTAINS


!------------------------------------------------------------------------------!
! Call for all grid points
!------------------------------------------------------------------------------!
    SUBROUTINE advec_s_pw( sk )

       USE arrays_3d
       USE control_parameters
       USE grid_variables
       USE indices

       IMPLICIT NONE

       INTEGER ::  i, j, k

#if defined( __nopointer )
       REAL, DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  sk
#else
       REAL, DIMENSION(:,:,:), POINTER ::  sk
#endif
 

       DO  i = nxl, nxr
          DO  j = nys, nyn
             DO  k = nzb_s_inner(j,i)+1, nzt
                tend(k,j,i) = tend(k,j,i)                                      &
              -0.5 * ( ( u(k,j,i+1) - u_gtrans ) * ( sk(k,j,i+1) - sk(k,j,i) ) &
                     - ( u(k,j,i)   - u_gtrans ) * ( sk(k,j,i-1) - sk(k,j,i) ) &
                     ) * ddx                                                   &
              -0.5 * ( ( v(k,j+1,i) - v_gtrans ) * ( sk(k,j+1,i) - sk(k,j,i) ) &
                     - ( v(k,j,i)   - v_gtrans ) * ( sk(k,j-1,i) - sk(k,j,i) ) &
                     ) * ddy                                                   &
              -      (   w(k,j,i)                * ( sk(k+1,j,i) - sk(k,j,i) ) &
                     -   w(k-1,j,i)              * ( sk(k-1,j,i) - sk(k,j,i) ) &
                     ) * dd2zu(k)
             ENDDO
          ENDDO
       ENDDO

    END SUBROUTINE advec_s_pw


!------------------------------------------------------------------------------!
! Call for grid point i,j
!------------------------------------------------------------------------------!
    SUBROUTINE advec_s_pw_ij( i, j, sk )

       USE arrays_3d
       USE control_parameters
       USE grid_variables
       USE indices

       IMPLICIT NONE

       INTEGER ::  i, j, k

#if defined( __nopointer )
       REAL, DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  sk
#else
       REAL, DIMENSION(:,:,:), POINTER ::  sk
#endif


       DO  k = nzb_s_inner(j,i)+1, nzt
          tend(k,j,i) = tend(k,j,i)                                            &
              -0.5 * ( ( u(k,j,i+1) - u_gtrans ) * ( sk(k,j,i+1) - sk(k,j,i) ) &
                     - ( u(k,j,i)   - u_gtrans ) * ( sk(k,j,i-1) - sk(k,j,i) ) &
                     ) * ddx                                                   &
              -0.5 * ( ( v(k,j+1,i) - v_gtrans ) * ( sk(k,j+1,i) - sk(k,j,i) ) &
                     - ( v(k,j,i)   - v_gtrans ) * ( sk(k,j-1,i) - sk(k,j,i) ) &
                     ) * ddy                                                   &
              -      (   w(k,j,i)                * ( sk(k+1,j,i) - sk(k,j,i) ) &
                     -   w(k-1,j,i)              * ( sk(k-1,j,i) - sk(k,j,i) ) &
                     ) * dd2zu(k)
       ENDDO

    END SUBROUTINE advec_s_pw_ij

 END MODULE advec_s_pw_mod