source: palm/trunk/SOURCE/subsidence_mod.f90 @ 4261

!> @file subsidence_mod.f90
!------------------------------------------------------------------------------!
! This file is part of the PALM model system.
!
! 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 1997-2019 Leibniz Universitaet Hannover
!------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
! 
! 
! Former revisions:
! -----------------
! $Id: subsidence_mod.f90 4182 2019-08-22 15:20:23Z scharf $
! Corrected "Former revisions" section
! 
! 3655 2019-01-07 16:51:22Z knoop
! add subroutine and variable description
!
! Revision 3.7 2009-12-11 14:15:58Z heinze
! Initial revision 
!
! Description:
! ------------
!> Impact of large-scale subsidence or ascent as tendency term for use 
!> in the prognostic equation of potential temperature. This enables the 
!> construction of a constant boundary layer height z_i with time.
!-----------------------------------------------------------------------------!
 MODULE subsidence_mod
 


    IMPLICIT NONE

    PRIVATE
    PUBLIC  init_w_subsidence, subsidence

    INTERFACE init_w_subsidence
       MODULE PROCEDURE init_w_subsidence
    END INTERFACE init_w_subsidence

    INTERFACE subsidence
       MODULE PROCEDURE subsidence
       MODULE PROCEDURE subsidence_ij
    END INTERFACE subsidence

 CONTAINS

!------------------------------------------------------------------------------!
! Description:
! ------------
!> Initialize vertical subsidence velocity w_subs.
!------------------------------------------------------------------------------!
    SUBROUTINE init_w_subsidence 

       USE arrays_3d,                                                          &
           ONLY:  dzu, w_subs, zu

       USE control_parameters,                                                 &
           ONLY:  message_string, ocean_mode, subs_vertical_gradient,          &
                  subs_vertical_gradient_level, subs_vertical_gradient_level_i

       USE indices,                                                            &
           ONLY:  nzb, nzt

       USE kinds

       IMPLICIT NONE

       INTEGER(iwp) ::  i !< loop index
       INTEGER(iwp) ::  k !< loop index

       REAL(wp)     ::  gradient   !< vertical gradient of subsidence velocity
       REAL(wp)     ::  ws_surface !< subsidence velocity at the surface

       IF ( .NOT. ALLOCATED( w_subs ) )  THEN
          ALLOCATE( w_subs(nzb:nzt+1) )
          w_subs = 0.0_wp
       ENDIF 

       IF ( ocean_mode )  THEN
          message_string = 'applying large scale vertical motion is not ' //   &
                           'allowed for ocean mode'
          CALL message( 'init_w_subsidence', 'PA0324', 2, 2, 0, 6, 0 )
       ENDIF

!
!--   Compute the profile of the subsidence/ascent velocity 
!--   using the given gradients
      i = 1
      gradient = 0.0_wp
      ws_surface = 0.0_wp
      

      subs_vertical_gradient_level_i(1) = 0
      DO  k = 1, nzt+1
         IF ( i < 11 )  THEN
            IF ( subs_vertical_gradient_level(i) < zu(k)  .AND. &
                 subs_vertical_gradient_level(i) >= 0.0_wp )  THEN
               gradient = subs_vertical_gradient(i) / 100.0_wp
               subs_vertical_gradient_level_i(i) = k - 1
               i = i + 1
            ENDIF
         ENDIF
         IF ( gradient /= 0.0_wp )  THEN
            IF ( k /= 1 )  THEN
               w_subs(k) = w_subs(k-1) + dzu(k) * gradient
            ELSE
               w_subs(k) = ws_surface   + 0.5_wp * dzu(k) * gradient
            ENDIF
         ELSE
            w_subs(k) = w_subs(k-1)
         ENDIF
      ENDDO

!
!--   In case of no given gradients for the subsidence/ascent velocity,
!--   choose zero gradient
      IF ( subs_vertical_gradient_level(1) == -9999999.9_wp )  THEN
         subs_vertical_gradient_level(1) = 0.0_wp
      ENDIF

    END SUBROUTINE init_w_subsidence


!------------------------------------------------------------------------------!
! Description:
! ------------
!> Add effect of large-scale subsidence to variable.
!------------------------------------------------------------------------------!
    SUBROUTINE subsidence( tendency, var, var_init, ls_index ) 

       USE arrays_3d,                                                          &
           ONLY:  ddzu, w_subs

       USE control_parameters,                                                 &
           ONLY:  dt_3d, intermediate_timestep_count, large_scale_forcing,     &
                  scalar_rayleigh_damping

       USE indices,                                                            &
           ONLY:  nxl, nxlg, nxr, nxrg, nyn, nyng, nys, nysg, nzb, nzt,        &
                  wall_flags_0

       USE kinds

       USE statistics,                                                         &
           ONLY:  sums_ls_l, weight_substep

       IMPLICIT NONE
 
       INTEGER(iwp) ::  i        !< loop index
       INTEGER(iwp) ::  j        !< loop index
       INTEGER(iwp) ::  k        !< loop index
       INTEGER(iwp) ::  ls_index !< index of large-scale subsidence in sums_ls_l

       REAL(wp)     ::  tmp_tend !< temporary tendency
       REAL(wp)     ::  tmp_grad !< temporary gradient 
    
       REAL(wp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  var      !< variable where to add subsidence
       REAL(wp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  tendency !< tendency of var
       REAL(wp), DIMENSION(nzb:nzt+1) ::  var_init                     !< initialization profile of var
       REAL(wp), DIMENSION(nzb:nzt+1) ::  var_mod                      !< modified profile of var

       var_mod = var_init

!
!--    Influence of w_subsidence on the current tendency term
       DO  i = nxl, nxr
          DO  j = nys, nyn

             DO  k = nzb+1, nzt 
                IF ( w_subs(k) < 0.0_wp )  THEN    ! large-scale subsidence
                   tmp_tend = - w_subs(k) *                                    &
                              ( var(k+1,j,i) - var(k,j,i) ) * ddzu(k+1) *      &
                                        MERGE( 1.0_wp, 0.0_wp,                 &
                                               BTEST( wall_flags_0(k,j,i), 0 ) )
                ELSE                               ! large-scale ascent
                   tmp_tend = - w_subs(k) *                                    &
                              ( var(k,j,i) - var(k-1,j,i) ) * ddzu(k) *        &
                                        MERGE( 1.0_wp, 0.0_wp,                 &
                                               BTEST( wall_flags_0(k,j,i), 0 ) )
                ENDIF

                tendency(k,j,i) = tendency(k,j,i) + tmp_tend

                IF ( large_scale_forcing )  THEN
                   sums_ls_l(k,ls_index) = sums_ls_l(k,ls_index) + tmp_tend    &
                                 * weight_substep(intermediate_timestep_count) &
                                 * MERGE( 1.0_wp, 0.0_wp,                      &
                                          BTEST( wall_flags_0(k,j,i), 0 ) )
                ENDIF
             ENDDO

             IF ( large_scale_forcing )  THEN
                sums_ls_l(nzt+1,ls_index) = sums_ls_l(nzt,ls_index)
             ENDIF

          ENDDO
       ENDDO

!
!--    Shifting of the initial profile is especially necessary with Rayleigh 
!--    damping switched on
       IF ( scalar_rayleigh_damping .AND.                                      &
            intermediate_timestep_count == 1 )  THEN
          DO  k = nzb, nzt
             IF ( w_subs(k) < 0.0_wp )  THEN      ! large-scale subsidence
                var_mod(k) = var_init(k) - dt_3d * w_subs(k) *  &
                                  ( var_init(k+1) - var_init(k) ) * ddzu(k+1)
             ENDIF
          ENDDO
!
!--      At the upper boundary, the initial profile is shifted with aid of 
!--      the gradient tmp_grad. (This is ok if the gradients are linear.)
         IF ( w_subs(nzt) < 0.0_wp )  THEN
            tmp_grad = ( var_init(nzt+1) - var_init(nzt) ) * ddzu(nzt+1)
            var_mod(nzt+1) = var_init(nzt+1) -  &
                                 dt_3d * w_subs(nzt+1) * tmp_grad
         ENDIF
       

         DO  k = nzt+1, nzb+1, -1
            IF ( w_subs(k) >= 0.0_wp )  THEN  ! large-scale ascent
               var_mod(k) = var_init(k) - dt_3d * w_subs(k) *  &
                                  ( var_init(k) - var_init(k-1) ) * ddzu(k) 
            ENDIF
         ENDDO
!
!--      At the lower boundary shifting is not necessary because the 
!--      subsidence velocity w_subs(nzb) vanishes.
         IF ( w_subs(nzb+1) >= 0.0_wp )  THEN
            var_mod(nzb) = var_init(nzb)
         ENDIF

         var_init = var_mod
      ENDIF


 END SUBROUTINE subsidence

!------------------------------------------------------------------------------!
! Description:
! ------------
!> Add effect of large-scale subsidence to variable.
!------------------------------------------------------------------------------!
 SUBROUTINE subsidence_ij( i, j, tendency, var, var_init, ls_index ) 

       USE arrays_3d,                                                          &
           ONLY:  ddzu, w_subs

       USE control_parameters,                                                 &
           ONLY:  dt_3d, intermediate_timestep_count, large_scale_forcing,     &
                  scalar_rayleigh_damping

       USE indices,                                                            &
           ONLY:  nxl, nxlg, nxrg, nyng, nys, nysg, nzb, nzt, wall_flags_0

       USE kinds

       USE statistics,                                                         &
           ONLY:  sums_ls_l, weight_substep

       IMPLICIT NONE
 
       INTEGER(iwp) ::  i        !< loop variable
       INTEGER(iwp) ::  j        !< loop variable
       INTEGER(iwp) ::  k        !< loop variable
       INTEGER(iwp) ::  ls_index !< index of large-scale subsidence in sums_ls_l

       REAL(wp)     ::  tmp_tend !< temporary tendency
       REAL(wp)     ::  tmp_grad !< temporary gradient
    
       REAL(wp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  var      !< variable where to add subsidence
       REAL(wp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ::  tendency !< tendency of var
       REAL(wp), DIMENSION(nzb:nzt+1) ::  var_init                     !< initialization profile of var
       REAL(wp), DIMENSION(nzb:nzt+1) ::  var_mod                      !< modified profile of var

       var_mod = var_init

!
!--    Influence of w_subsidence on the current tendency term
       DO  k = nzb+1, nzt 
          IF ( w_subs(k) < 0.0_wp )  THEN      ! large-scale subsidence
             tmp_tend = - w_subs(k) * ( var(k+1,j,i) - var(k,j,i) )            &
                                    * ddzu(k+1)                                &
                                    * MERGE( 1.0_wp, 0.0_wp,                   &
                                             BTEST( wall_flags_0(k,j,i), 0 ) )
          ELSE                                 ! large-scale ascent
             tmp_tend = - w_subs(k) * ( var(k,j,i) - var(k-1,j,i) ) * ddzu(k)  &
                                    * MERGE( 1.0_wp, 0.0_wp,                   &
                                             BTEST( wall_flags_0(k,j,i), 0 ) )
          ENDIF

          tendency(k,j,i) = tendency(k,j,i) + tmp_tend

          IF ( large_scale_forcing )  THEN
             sums_ls_l(k,ls_index) = sums_ls_l(k,ls_index) + tmp_tend          &
                                  * weight_substep(intermediate_timestep_count)&
                                  * MERGE( 1.0_wp, 0.0_wp,                     &
                                           BTEST( wall_flags_0(k,j,i), 0 ) )
          ENDIF
       ENDDO

       IF ( large_scale_forcing )  THEN
          sums_ls_l(nzt+1,ls_index) = sums_ls_l(nzt,ls_index)
       ENDIF

!
!--    Shifting of the initial profile is especially necessary with Rayleigh 
!--    damping switched on
       IF ( scalar_rayleigh_damping .AND.                                      &
            intermediate_timestep_count == 1 )  THEN
          IF ( i == nxl .AND. j == nys )  THEN ! shifting only once per PE 

             DO  k = nzb, nzt
                IF ( w_subs(k) < 0.0_wp )  THEN      ! large-scale subsidence
                   var_mod(k) = var_init(k) - dt_3d * w_subs(k) *  &
                                     ( var_init(k+1) - var_init(k) ) * ddzu(k+1)
                ENDIF
             ENDDO
!
!--          At the upper boundary, the initial profile is shifted with aid of 
!--          the gradient tmp_grad. (This is ok if the gradients are linear.)
             IF ( w_subs(nzt) < 0.0_wp )  THEN
                tmp_grad = ( var_init(nzt+1) - var_init(nzt) ) * ddzu(nzt+1)
                var_mod(nzt+1) = var_init(nzt+1) -  &
                                     dt_3d * w_subs(nzt+1) * tmp_grad
             ENDIF
       

             DO  k = nzt+1, nzb+1, -1
                IF ( w_subs(k) >= 0.0_wp )  THEN  ! large-scale ascent
                   var_mod(k) = var_init(k) - dt_3d * w_subs(k) *  &
                                      ( var_init(k) - var_init(k-1) ) * ddzu(k)
                ENDIF
             ENDDO
!
!--          At the lower boundary shifting is not necessary because the 
!--          subsidence velocity w_subs(nzb) vanishes.
             IF ( w_subs(nzb+1) >= 0.0_wp )  THEN
                var_mod(nzb) = var_init(nzb)
             ENDIF

             var_init = var_mod 

          ENDIF
       ENDIF

 END SUBROUTINE subsidence_ij


 END MODULE subsidence_mod