MODULE advec_s_pw_mod

!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2014 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
!
!
! Former revisions:
! -----------------
! $Id: advec_s_pw.f90 1321 2014-03-20 09:40:40Z maronga $
!
! 1320 2014-03-20 08:40:49Z raasch
! ONLY-attribute added to USE-statements,
! kind-parameters added to all INTEGER and REAL declaration statements,
! kinds are defined in new module kinds,
! revision history before 2012 removed,
! comment fields (!:) to be used for variable explanations added to
! all variable declaration statements
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 1010 2012-09-20 07:59:54Z raasch
! cpp switch __nopointer added for pointer free version
!
! 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,                                                          &
           ONLY:  dd2zu, tend, u, v, w

       USE control_parameters,                                                 &
           ONLY:  u_gtrans, v_gtrans

       USE grid_variables,                                                     &
           ONLY:  ddx, ddy

       USE indices,                                                            &
           ONLY:  nxl, nxr, nyn, nys, nzb_s_inner, nzt

       USE kinds


       IMPLICIT NONE

       INTEGER(iwp) ::  i !:
       INTEGER(iwp) ::  j !:
       INTEGER(iwp) ::  k !:

#if defined( __nopointer )
       REAL(wp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  sk !:
#else
       REAL(wp), 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,                                                          &
           ONLY:  dd2zu, tend, u, v, w

       USE control_parameters,                                                 &
           ONLY:  u_gtrans, v_gtrans

       USE grid_variables,                                                     &
           ONLY:  ddx, ddy

       USE indices,                                                            &
           ONLY:  nzb_s_inner, nzt

       USE kinds


       IMPLICIT NONE

       INTEGER(iwp) ::  i !:
       INTEGER(iwp) ::  j !:
       INTEGER(iwp) ::  k !:

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