source: palm/trunk/SOURCE/init_3d_model.f90 @ 77

#if defined( __ibmy_special )
@PROCESS NOOPTimize
#endif
 SUBROUTINE init_3d_model

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: init_3d_model.f90 77 2007-03-29 04:26:56Z raasch $
!
! 75 2007-03-22 09:54:05Z raasch
! Arrays for radiation boundary conditions are allocated (u_m_l, u_m_r, etc.),
! bugfix for cases with the outflow damping layer extending over more than one
! subdomain, moisture renamed humidity,
! new initializing action "by_user" calls user_init_3d_model,
! precipitation_amount/rate, ts_value are allocated, +module netcdf_control,
! initial velocities at nzb+1 are regarded for volume
! flow control in case they have been set zero before (to avoid small timesteps)
! -uvmean_outflow, uxrp, vynp eliminated
!
! 19 2007-02-23 04:53:48Z raasch
! +handling of top fluxes
!
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.49  2006/08/22 15:59:07  raasch
! No optimization of this file on the ibmy (Yonsei Univ.)
!
! Revision 1.1  1998/03/09 16:22:22  raasch
! Initial revision
!
!
! Description:
! ------------
! Allocation of arrays and initialization of the 3D model via
! a) pre-run the 1D model
! or
! b) pre-set constant linear profiles
! or
! c) read values of a previous run
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE averaging
    USE cloud_parameters
    USE constants
    USE control_parameters
    USE cpulog
    USE indices
    USE interfaces
    USE model_1d
    USE netcdf_control
    USE particle_attributes
    USE pegrid
    USE profil_parameter
    USE random_function_mod
    USE statistics

    IMPLICIT NONE

    INTEGER ::  i, j, k, sr

    INTEGER, DIMENSION(:), ALLOCATABLE ::  ngp_2dh_l, ngp_3d_inner_l

    INTEGER, DIMENSION(:,:), ALLOCATABLE ::  ngp_2dh_outer_l

    REAL, DIMENSION(1:2) ::  volume_flow_area_l, volume_flow_initial_l


!
!-- Allocate arrays
    ALLOCATE( ngp_2dh(0:statistic_regions), ngp_2dh_l(0:statistic_regions), &
              ngp_3d(0:statistic_regions),                                  &
              ngp_3d_inner(0:statistic_regions),                            &
              ngp_3d_inner_l(0:statistic_regions),                          &
              sums_divnew_l(0:statistic_regions),                           &
              sums_divold_l(0:statistic_regions) )
    ALLOCATE( rdf(nzb+1:nzt) )
    ALLOCATE( hom_sum(nzb:nzt+1,var_hom,0:statistic_regions),               &
              ngp_2dh_outer(nzb:nzt+1,0:statistic_regions),                 &
              ngp_2dh_outer_l(nzb:nzt+1,0:statistic_regions),               &
              rmask(nys-1:nyn+1,nxl-1:nxr+1,0:statistic_regions),           &
              sums(nzb:nzt+1,var_sum),                                      &
              sums_l(nzb:nzt+1,var_sum,0:threads_per_task-1),               &
              sums_l_l(nzb:nzt+1,0:statistic_regions,0:threads_per_task-1), &
              sums_up_fraction_l(10,3,0:statistic_regions),                 &
              sums_wsts_bc_l(nzb:nzt+1,0:statistic_regions),                &
              ts_value(var_ts,0:statistic_regions) )
    ALLOCATE( km_damp_x(nxl-1:nxr+1), km_damp_y(nys-1:nyn+1) )

    ALLOCATE( rif_1(nys-1:nyn+1,nxl-1:nxr+1), shf_1(nys-1:nyn+1,nxl-1:nxr+1), &
              ts(nys-1:nyn+1,nxl-1:nxr+1), tswst_1(nys-1:nyn+1,nxl-1:nxr+1),  &
              us(nys-1:nyn+1,nxl-1:nxr+1), usws_1(nys-1:nyn+1,nxl-1:nxr+1),   &
              vsws_1(nys-1:nyn+1,nxl-1:nxr+1), z0(nys-1:nyn+1,nxl-1:nxr+1) )

    IF ( timestep_scheme(1:5) /= 'runge' )  THEN
!
!--    Leapfrog scheme needs two timelevels of diffusion quantities
       ALLOCATE( rif_2(nys-1:nyn+1,nxl-1:nxr+1),   &
                 shf_2(nys-1:nyn+1,nxl-1:nxr+1),   &
                 tswst_2(nys-1:nyn+1,nxl-1:nxr+1), &
                 usws_2(nys-1:nyn+1,nxl-1:nxr+1),  &
                 vsws_2(nys-1:nyn+1,nxl-1:nxr+1) )
    ENDIF

    ALLOCATE( d(nzb+1:nzta,nys:nyna,nxl:nxra),         &
              e_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              e_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              e_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              kh_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              km_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              p(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),    &
              pt_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              pt_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              pt_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              tend(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              u_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              u_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              u_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              v_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              v_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              v_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
              w_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              w_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1),  &
              w_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )

    IF ( timestep_scheme(1:5) /= 'runge' )  THEN
       ALLOCATE( kh_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                 km_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
    ENDIF

    IF ( humidity  .OR.  passive_scalar ) THEN
!
!--    2D-humidity/scalar arrays
       ALLOCATE ( qs(nys-1:nyn+1,nxl-1:nxr+1),     &
                  qsws_1(nys-1:nyn+1,nxl-1:nxr+1), &
                  qswst_1(nys-1:nyn+1,nxl-1:nxr+1) )

       IF ( timestep_scheme(1:5) /= 'runge' )  THEN
          ALLOCATE( qsws_2(nys-1:nyn+1,nxl-1:nxr+1), &
                    qswst_2(nys-1:nyn+1,nxl-1:nxr+1) )
       ENDIF
!
!--    3D-humidity/scalar arrays
       ALLOCATE( q_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                 q_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                 q_3(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )

!
!--    3D-arrays needed for humidity only
       IF ( humidity )  THEN
          ALLOCATE( vpt_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )

          IF ( timestep_scheme(1:5) /= 'runge' )  THEN
             ALLOCATE( vpt_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
          ENDIF

          IF ( cloud_physics ) THEN
!
!--          Liquid water content
             ALLOCATE ( ql_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
!
!--          Precipitation amount and rate (only needed if output is switched)
             ALLOCATE( precipitation_amount(nys-1:nyn+1,nxl-1:nxr+1), &
                       precipitation_rate(nys-1:nyn+1,nxl-1:nxr+1) )
          ENDIF

          IF ( cloud_droplets )  THEN
!
!--          Liquid water content, change in liquid water content,
!--          real volume of particles (with weighting), volume of particles
             ALLOCATE ( ql_1(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                        ql_2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                        ql_v(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1), &
                        ql_vp(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
          ENDIF

       ENDIF

    ENDIF

!
!-- 3D-array for storing the dissipation, needed for calculating the sgs
!-- particle velocities
    IF ( use_sgs_for_particles )  THEN
       ALLOCATE ( diss(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
    ENDIF

    IF ( dt_dosp /= 9999999.9 )  THEN
       ALLOCATE( spectrum_x( 1:nx/2, 1:10, 1:10 ), &
                 spectrum_y( 1:ny/2, 1:10, 1:10 ) )
    ENDIF

!
!-- 4D-array for storing the Rif-values at vertical walls
    IF ( topography /= 'flat' )  THEN
       ALLOCATE( rif_wall(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1,1:4) )
       rif_wall = 0.0
    ENDIF

!
!-- Velocities at nzb+1 needed for volume flow control
    IF ( conserve_volume_flow )  THEN
       ALLOCATE( u_nzb_p1_for_vfc(nys:nyn), v_nzb_p1_for_vfc(nxl:nxr) )
       u_nzb_p1_for_vfc = 0.0
       v_nzb_p1_for_vfc = 0.0
    ENDIF

!
!-- Arrays to store velocity data from t-dt needed for radiation boundary
!-- conditions
    IF ( outflow_l )  THEN
       ALLOCATE( u_m_l(nzb:nzt+1,nys-1:nyn+1,-1:1), &
                 v_m_l(nzb:nzt+1,nys-1:nyn+1,-1:1), &
                 w_m_l(nzb:nzt+1,nys-1:nyn+1,-1:1) )
    ENDIF
    IF ( outflow_r )  THEN
       ALLOCATE( u_m_r(nzb:nzt+1,nys-1:nyn+1,nx-1:nx+1), &
                 v_m_r(nzb:nzt+1,nys-1:nyn+1,nx-1:nx+1), &
                 w_m_r(nzb:nzt+1,nys-1:nyn+1,nx-1:nx+1) )
    ENDIF
    IF ( outflow_s )  THEN
       ALLOCATE( u_m_s(nzb:nzt+1,-1:1,nxl-1:nxr+1), &
                 v_m_s(nzb:nzt+1,-1:1,nxl-1:nxr+1), &
                 w_m_s(nzb:nzt+1,-1:1,nxl-1:nxr+1) )
    ENDIF
    IF ( outflow_n )  THEN
       ALLOCATE( u_m_n(nzb:nzt+1,ny-1:ny+1,nxl-1:nxr+1), &
                 v_m_n(nzb:nzt+1,ny-1:ny+1,nxl-1:nxr+1), &
                 w_m_n(nzb:nzt+1,ny-1:ny+1,nxl-1:nxr+1) )
    ENDIF

!
!-- Initial assignment of the pointers
    IF ( timestep_scheme(1:5) /= 'runge' )  THEN

       rif_m   => rif_1;    rif   => rif_2
       shf_m   => shf_1;    shf   => shf_2
       tswst_m => tswst_1;  tswst => tswst_2
       usws_m  => usws_1;   usws  => usws_2
       vsws_m  => vsws_1;   vsws  => vsws_2
       e_m  => e_1;   e  => e_2;   e_p  => e_3;   te_m  => e_3
       kh_m => kh_1;  kh => kh_2
       km_m => km_1;  km => km_2
       pt_m => pt_1;  pt => pt_2;  pt_p => pt_3;  tpt_m => pt_3
       u_m  => u_1;   u  => u_2;   u_p  => u_3;   tu_m  => u_3
       v_m  => v_1;   v  => v_2;   v_p  => v_3;   tv_m  => v_3
       w_m  => w_1;   w  => w_2;   w_p  => w_3;   tw_m  => w_3

       IF ( humidity  .OR.  passive_scalar )  THEN
          qsws_m  => qsws_1;   qsws  => qsws_2
          qswst_m => qswst_1;  qswst => qswst_2
          q_m    => q_1;     q    => q_2;     q_p => q_3;     tq_m => q_3
          IF ( humidity )        vpt_m  => vpt_1;   vpt  => vpt_2
          IF ( cloud_physics )   ql   => ql_1
          IF ( cloud_droplets )  THEN
             ql   => ql_1
             ql_c => ql_2
          ENDIF
       ENDIF

    ELSE

       rif   => rif_1
       shf   => shf_1
       tswst => tswst_1
       usws  => usws_1
       vsws  => vsws_1
       e     => e_1;   e_p  => e_2;   te_m  => e_3;   e_m  => e_3
       kh    => kh_1
       km    => km_1
       pt    => pt_1;  pt_p => pt_2;  tpt_m => pt_3;  pt_m => pt_3
       u     => u_1;   u_p  => u_2;   tu_m  => u_3;   u_m  => u_3
       v     => v_1;   v_p  => v_2;   tv_m  => v_3;   v_m  => v_3
       w     => w_1;   w_p  => w_2;   tw_m  => w_3;   w_m  => w_3

       IF ( humidity  .OR.  passive_scalar )  THEN
          qsws   => qsws_1
          qswst  => qswst_1
          q      => q_1;     q_p  => q_2;     tq_m => q_3;    q_m => q_3
          IF ( humidity )        vpt  => vpt_1
          IF ( cloud_physics )   ql   => ql_1
          IF ( cloud_droplets )  THEN
             ql   => ql_1
             ql_c => ql_2
          ENDIF
       ENDIF

    ENDIF

!
!-- Initialize model variables
    IF ( TRIM( initializing_actions ) /= 'read_restart_data' )  THEN
!
!--    First model run of a possible job queue.
!--    Initial profiles of the variables must be computes.
       IF ( INDEX( initializing_actions, 'set_1d-model_profiles' ) /= 0 )  THEN
!
!--       Use solutions of the 1D model as initial profiles,
!--       start 1D model
          CALL init_1d_model
!
!--       Transfer initial profiles to the arrays of the 3D model
          DO  i = nxl-1, nxr+1
             DO  j = nys-1, nyn+1
                e(:,j,i)  = e1d
                kh(:,j,i) = kh1d
                km(:,j,i) = km1d
                pt(:,j,i) = pt_init
                u(:,j,i)  = u1d
                v(:,j,i)  = v1d
             ENDDO
          ENDDO

          IF ( humidity  .OR.  passive_scalar )  THEN
             DO  i = nxl-1, nxr+1
                DO  j = nys-1, nyn+1
                   q(:,j,i) = q_init
                ENDDO
             ENDDO
          ENDIF

          IF ( .NOT. constant_diffusion )  THEN
             DO  i = nxl-1, nxr+1
                DO  j = nys-1, nyn+1
                   e(:,j,i)  = e1d
                ENDDO
             ENDDO
!
!--          Store initial profiles for output purposes etc.
             hom(:,1,25,:) = SPREAD( l1d, 2, statistic_regions+1 )

             IF ( prandtl_layer )  THEN
                rif  = rif1d(nzb+1)
                ts   = 0.0  ! could actually be computed more accurately in the
                            ! 1D model. Update when opportunity arises.
                us   = us1d
                usws = usws1d
                vsws = vsws1d
             ELSE
                ts   = 0.0  ! must be set, because used in
                rif  = 0.0  ! flowste
                us   = 0.0
                usws = 0.0
                vsws = 0.0
             ENDIF

          ELSE
             e    = 0.0  ! must be set, because used in
             rif  = 0.0  ! flowste
             ts   = 0.0
             us   = 0.0
             usws = 0.0
             vsws = 0.0
          ENDIF

!
!--       In every case qs = 0.0 (see also pt)
!--       This could actually be computed more accurately in the 1D model.
!--       Update when opportunity arises!
          IF ( humidity  .OR.  passive_scalar )  qs = 0.0

!
!--       inside buildings set velocities back to zero
          IF ( topography /= 'flat' )  THEN
             DO  i = nxl-1, nxr+1
                DO  j = nys-1, nyn+1
                   u(nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v(nzb:nzb_v_inner(j,i),j,i) = 0.0
                ENDDO
             ENDDO
!
!--          WARNING: The extra boundary conditions set after running the
!--          -------  1D model impose an error on the divergence one layer
!--                   below the topography; need to correct later 
!--          ATTENTION: Provisional correction for Piacsek & Williams
!--          ---------  advection scheme: keep u and v zero one layer below
!--                     the topography.
             IF ( ibc_uv_b == 0 )  THEN
!
!--             Satisfying the Dirichlet condition with an extra layer below
!--             the surface where the u and v component change their sign.
                DO  i = nxl-1, nxr+1
                   DO  j = nys-1, nyn+1
                      IF ( nzb_u_inner(j,i) == 0 ) u(0,j,i) = -u(1,j,i)
                      IF ( nzb_v_inner(j,i) == 0 ) v(0,j,i) = -v(1,j,i)
                   ENDDO
                ENDDO

             ELSE
!
!--             Neumann condition
                DO  i = nxl-1, nxr+1
                   DO  j = nys-1, nyn+1
                      IF ( nzb_u_inner(j,i) == 0 ) u(0,j,i) = u(1,j,i)
                      IF ( nzb_v_inner(j,i) == 0 ) v(0,j,i) = v(1,j,i)
                   ENDDO
                ENDDO

             ENDIF

          ENDIF

       ELSEIF ( INDEX(initializing_actions, 'set_constant_profiles') /= 0 ) &
       THEN
!
!--       Use constructed initial profiles (velocity constant with height,
!--       temperature profile with constant gradient)
          DO  i = nxl-1, nxr+1
             DO  j = nys-1, nyn+1
                pt(:,j,i) = pt_init
                u(:,j,i)  = u_init
                v(:,j,i)  = v_init
             ENDDO
          ENDDO

!
!--       Set initial horizontal velocities at the lowest computational grid levels
!--       to zero in order to avoid too small time steps caused by the diffusion
!--       limit in the initial phase of a run (at k=1, dz/2 occurs in the
!--       limiting formula!). The original values are stored to be later used for
!--       volume flow control.
          DO  i = nxl-1, nxr+1
             DO  j = nys-1, nyn+1
                u(nzb:nzb_u_inner(j,i)+1,j,i) = 0.0
                v(nzb:nzb_v_inner(j,i)+1,j,i) = 0.0
             ENDDO
          ENDDO
          IF ( conserve_volume_flow )  THEN
             IF ( nxr == nx )  THEN
                DO  j = nys, nyn
                   k = nzb_u_inner(j,nx) + 1
                   u_nzb_p1_for_vfc(j) = u_init(k) * dzu(k)
                ENDDO
             ENDIF
             IF ( nyn == ny )  THEN
                DO  i = nxl, nxr
                   k = nzb_v_inner(ny,i) + 1
                   v_nzb_p1_for_vfc(i) = v_init(k) * dzu(k)
                ENDDO
             ENDIF
          ENDIF

          IF ( humidity  .OR.  passive_scalar )  THEN
             DO  i = nxl-1, nxr+1
                DO  j = nys-1, nyn+1
                   q(:,j,i) = q_init
                ENDDO
             ENDDO
          ENDIF

          
          IF ( constant_diffusion )  THEN
             km   = km_constant
             kh   = km / prandtl_number
          ELSE
             kh   = 0.01   ! there must exist an initial diffusion, because 
             km   = 0.01   ! otherwise no TKE would be produced by the
                           ! production terms, as long as not yet
                           ! e = (u*/cm)**2 at k=nzb+1
          ENDIF
          e    = 0.0
          rif  = 0.0
          ts   = 0.0
          us   = 0.0
          usws = 0.0
          vsws = 0.0
          IF ( humidity  .OR.  passive_scalar ) qs = 0.0

!
!--       Compute initial temperature field and other constants used in case
!--       of a sloping surface
          IF ( sloping_surface )  CALL init_slope

       ELSEIF ( INDEX(initializing_actions, 'by_user') /= 0 ) &
       THEN
!
!--       Initialization will completely be done by the user
          CALL user_init_3d_model

       ENDIF

!
!--    Calculate virtual potential temperature
       IF ( humidity ) vpt = pt * ( 1.0 + 0.61 * q )

!
!--    Store initial profiles for output purposes etc.
       hom(:,1,5,:) = SPREAD( u(:,nys,nxl), 2, statistic_regions+1 )
       hom(:,1,6,:) = SPREAD( v(:,nys,nxl), 2, statistic_regions+1 )
       IF ( ibc_uv_b == 0 )  THEN
          hom(nzb,1,5,:) = -hom(nzb+1,1,5,:)  ! due to satisfying the Dirichlet 
          hom(nzb,1,6,:) = -hom(nzb+1,1,6,:)  ! condition with an extra layer 
              ! below the surface where the u and v component change their sign
       ENDIF
       hom(:,1,7,:)  = SPREAD( pt(:,nys,nxl), 2, statistic_regions+1 )
       hom(:,1,23,:) = SPREAD( km(:,nys,nxl), 2, statistic_regions+1 )
       hom(:,1,24,:) = SPREAD( kh(:,nys,nxl), 2, statistic_regions+1 )


       IF ( humidity )  THEN
!
!--       Store initial profile of total water content, virtual potential
!--       temperature 
          hom(:,1,26,:) = SPREAD(   q(:,nys,nxl), 2, statistic_regions+1 )
          hom(:,1,29,:) = SPREAD( vpt(:,nys,nxl), 2, statistic_regions+1 )
          IF ( cloud_physics  .OR.  cloud_droplets ) THEN
!
!--          Store initial profile of specific humidity and potential
!--          temperature
             hom(:,1,27,:) = SPREAD(  q(:,nys,nxl), 2, statistic_regions+1 )
             hom(:,1,28,:) = SPREAD( pt(:,nys,nxl), 2, statistic_regions+1 )
          ENDIF
       ENDIF

       IF ( passive_scalar )  THEN
!
!--       Store initial scalar profile
          hom(:,1,26,:) = SPREAD(  q(:,nys,nxl), 2, statistic_regions+1 )
       ENDIF

!
!--    Initialize fluxes at bottom surface
       IF ( use_surface_fluxes )  THEN

          IF ( constant_heatflux )  THEN
!
!--          Heat flux is prescribed
             IF ( random_heatflux )  THEN
                CALL disturb_heatflux
             ELSE
                shf = surface_heatflux
!
!--             Over topography surface_heatflux is replaced by wall_heatflux(0)
                IF ( TRIM( topography ) /= 'flat' )  THEN
                   DO  i = nxl-1, nxr+1
                      DO  j = nys-1, nyn+1
                         IF ( nzb_s_inner(j,i) /= 0 )  THEN
                            shf(j,i) = wall_heatflux(0)
                         ENDIF
                      ENDDO
                   ENDDO
                ENDIF
             ENDIF
             IF ( ASSOCIATED( shf_m ) )  shf_m = shf
          ENDIF

!
!--       Determine the near-surface water flux
          IF ( humidity  .OR.  passive_scalar )  THEN
             IF ( constant_waterflux )  THEN
                qsws   = surface_waterflux
                IF ( ASSOCIATED( qsws_m ) )  qsws_m = qsws
             ENDIF
          ENDIF

       ENDIF

!
!--    Initialize fluxes at top surface
!--    Currently, only the heatflux can be prescribed. The latent flux is
!--    zero in this case!
       IF ( use_top_fluxes )  THEN

          IF ( constant_top_heatflux )  THEN
!
!--          Heat flux is prescribed
             tswst = top_heatflux
             IF ( ASSOCIATED( tswst_m ) )  tswst_m = tswst

             IF ( humidity  .OR.  passive_scalar )  THEN
                qswst = 0.0
                IF ( ASSOCIATED( qswst_m ) )  qswst_m = qswst
             ENDIF
         ENDIF

       ENDIF

!
!--    Initialize Prandtl layer quantities
       IF ( prandtl_layer )  THEN

          z0 = roughness_length

          IF ( .NOT. constant_heatflux )  THEN 
!
!--          Surface temperature is prescribed. Here the heat flux cannot be
!--          simply estimated, because therefore rif, u* and theta* would have
!--          to be computed by iteration. This is why the heat flux is assumed
!--          to be zero before the first time step. It approaches its correct
!--          value in the course of the first few time steps.
             shf   = 0.0
             IF ( ASSOCIATED( shf_m ) )  shf_m = 0.0
          ENDIF

          IF ( humidity  .OR.  passive_scalar )  THEN
             IF ( .NOT. constant_waterflux )  THEN
                qsws   = 0.0
                IF ( ASSOCIATED( qsws_m ) )   qsws_m = 0.0
             ENDIF
          ENDIF

       ENDIF

!
!--    Calculate the initial volume flow at the right and north boundary
       IF ( conserve_volume_flow )  THEN

          volume_flow_initial_l = 0.0
          volume_flow_area_l    = 0.0
  
          IF ( nxr == nx )  THEN
             DO  j = nys, nyn
                DO  k = nzb_2d(j,nx) + 1, nzt
                   volume_flow_initial_l(1) = volume_flow_initial_l(1) + &
                                              u(k,j,nx) * dzu(k)
                   volume_flow_area_l(1)    = volume_flow_area_l(1) + dzu(k)
                ENDDO
!
!--             Correction if velocity at nzb+1 has been set zero further above
                volume_flow_initial_l(1) = volume_flow_initial_l(1) + &
                                           u_nzb_p1_for_vfc(j)
             ENDDO
          ENDIF

          IF ( nyn == ny )  THEN
             DO  i = nxl, nxr
                DO  k = nzb_2d(ny,i) + 1, nzt  
                   volume_flow_initial_l(2) = volume_flow_initial_l(2) + &
                                              v(k,ny,i) * dzu(k)
                   volume_flow_area_l(2)    = volume_flow_area_l(2) + dzu(k)
                ENDDO
!
!--             Correction if velocity at nzb+1 has been set zero further above
                volume_flow_initial_l(2) = volume_flow_initial_l(2) + &
                                           v_nzb_p1_for_vfc(i)
             ENDDO
          ENDIF

#if defined( __parallel )
          CALL MPI_ALLREDUCE( volume_flow_initial_l(1), volume_flow_initial(1),&
                              2, MPI_REAL, MPI_SUM, comm2d, ierr )
          CALL MPI_ALLREDUCE( volume_flow_area_l(1), volume_flow_area(1),      &
                              2, MPI_REAL, MPI_SUM, comm2d, ierr )
#else
          volume_flow_initial = volume_flow_initial_l
          volume_flow_area    = volume_flow_area_l
#endif  
       ENDIF

!
!--    For the moment, perturbation pressure and vertical velocity are zero
       p = 0.0; w = 0.0

!
!--    Initialize array sums (must be defined in first call of pres)
       sums = 0.0

!
!--    Treating cloud physics, liquid water content and precipitation amount
!--    are zero at beginning of the simulation
       IF ( cloud_physics )  THEN
          ql = 0.0
          IF ( precipitation )  precipitation_amount = 0.0
       ENDIF

!
!--    Initialize spectra
       IF ( dt_dosp /= 9999999.9 )  THEN
          spectrum_x = 0.0
          spectrum_y = 0.0
       ENDIF

!
!--    Impose vortex with vertical axis on the initial velocity profile
       IF ( INDEX( initializing_actions, 'initialize_vortex' ) /= 0 )  THEN
          CALL init_rankine
       ENDIF

!
!--    Impose temperature anomaly (advection test only)
       IF ( INDEX( initializing_actions, 'initialize_ptanom' ) /= 0 )  THEN
          CALL init_pt_anomaly
       ENDIF

!
!--    If required, change the surface temperature at the start of the 3D run
       IF ( pt_surface_initial_change /= 0.0 )  THEN
          pt(nzb,:,:) = pt(nzb,:,:) + pt_surface_initial_change
       ENDIF

!
!--    If required, change the surface humidity/scalar at the start of the 3D
!--    run
       IF ( ( humidity .OR. passive_scalar ) .AND. &
            q_surface_initial_change /= 0.0 )  THEN
          q(nzb,:,:) = q(nzb,:,:) + q_surface_initial_change
       ENDIF

!
!--    Initialize the random number generator (from numerical recipes)
       CALL random_function_ini

!
!--    Impose random perturbation on the horizontal velocity field and then
!--    remove the divergences from the velocity field
       IF ( create_disturbances )  THEN
          CALL disturb_field( nzb_u_inner, tend, u )
          CALL disturb_field( nzb_v_inner, tend, v )
          n_sor = nsor_ini
          CALL pres
          n_sor = nsor
       ENDIF

!
!--    Once again set the perturbation pressure explicitly to zero in order to
!--    assure that it does not generate any divergences in the first time step.
!--    At t=0 the velocity field is free of divergence (as constructed above).
!--    Divergences being created during a time step are not yet known and thus
!--    cannot be corrected during the time step yet.
       p = 0.0

!
!--    Initialize old and new time levels.
       IF ( timestep_scheme(1:5) /= 'runge' )  THEN
          e_m = e; pt_m = pt; u_m = u; v_m = v; w_m = w; kh_m = kh; km_m = km
       ELSE
          te_m = 0.0; tpt_m = 0.0; tu_m = 0.0; tv_m = 0.0; tw_m = 0.0
       ENDIF
       e_p = e; pt_p = pt; u_p = u; v_p = v; w_p = w

       IF ( humidity  .OR.  passive_scalar )  THEN
          IF ( ASSOCIATED( q_m ) )  q_m = q
          IF ( timestep_scheme(1:5) == 'runge' )  tq_m = 0.0
          q_p = q
          IF ( humidity  .AND.  ASSOCIATED( vpt_m ) )  vpt_m = vpt
       ENDIF

!
!--    Initialize old timelevels needed for radiation boundary conditions
       IF ( outflow_l )  THEN
          u_m_l(:,:,:) = u(:,:,-1:1)
          v_m_l(:,:,:) = v(:,:,-1:1)
          w_m_l(:,:,:) = w(:,:,-1:1)
       ENDIF
       IF ( outflow_r )  THEN
          u_m_r(:,:,:) = u(:,:,nx-1:nx+1)
          v_m_r(:,:,:) = v(:,:,nx-1:nx+1)
          w_m_r(:,:,:) = w(:,:,nx-1:nx+1)
       ENDIF
       IF ( outflow_s )  THEN
          u_m_s(:,:,:) = u(:,-1:1,:)
          v_m_s(:,:,:) = v(:,-1:1,:)
          w_m_s(:,:,:) = w(:,-1:1,:)
       ENDIF
       IF ( outflow_n )  THEN
          u_m_n(:,:,:) = u(:,ny-1:ny+1,:)
          v_m_n(:,:,:) = v(:,ny-1:ny+1,:)
          w_m_n(:,:,:) = w(:,ny-1:ny+1,:)
       ENDIF

    ELSEIF ( TRIM( initializing_actions ) == 'read_restart_data' ) &
    THEN
!
!--    Read binary data from restart file
       CALL read_3d_binary

!
!--    Calculate initial temperature field and other constants used in case
!--    of a sloping surface
       IF ( sloping_surface )  CALL init_slope

!
!--    Initialize new time levels (only done in order to set boundary values
!--    including ghost points)
       e_p = e; pt_p = pt; u_p = u; v_p = v; w_p = w
       IF ( humidity  .OR.  passive_scalar )  q_p = q

    ELSE
!
!--    Actually this part of the programm should not be reached
       IF ( myid == 0 )  PRINT*,'+++ init_3d_model: unknown initializing ', &
                                                    'problem'
       CALL local_stop
    ENDIF

!
!-- If required, initialize dvrp-software
    IF ( dt_dvrp /= 9999999.9 )  CALL init_dvrp

!
!-- If required, initialize quantities for handling cloud physics
!-- This routine must be called before init_particles, because
!-- otherwise, array pt_d_t, needed in data_output_dvrp (called by
!-- init_particles) is not defined.
    CALL init_cloud_physics

!
!-- If required, initialize particles
    IF ( particle_advection )  CALL init_particles

!
!-- Initialize quantities for special advections schemes
    CALL init_advec

!
!-- Initialize Rayleigh damping factors
    rdf = 0.0
    IF ( rayleigh_damping_factor /= 0.0 )  THEN
       DO  k = nzb+1, nzt
          IF ( zu(k) >= rayleigh_damping_height )  THEN
             rdf(k) = rayleigh_damping_factor * &
                      ( SIN( pi * 0.5 * ( zu(k) - rayleigh_damping_height )    &
                                      / ( zu(nzt) - rayleigh_damping_height ) )&
                      )**2
          ENDIF
       ENDDO
    ENDIF

!
!-- Initialize diffusivities used within the outflow damping layer in case of
!-- non-cyclic lateral boundaries. A linear increase is assumed over the first
!-- half of the width of the damping layer
    IF ( bc_lr == 'dirichlet/radiation' )  THEN

       DO  i = nxl-1, nxr+1
          IF ( i >= nx - outflow_damping_width )  THEN
             km_damp_x(i) = km_damp_max * MIN( 1.0,                    &
                            ( i - ( nx - outflow_damping_width ) ) /   &
                            REAL( outflow_damping_width/2 )            &
                                             )
          ELSE
             km_damp_x(i) = 0.0
          ENDIF
       ENDDO

    ELSEIF ( bc_lr == 'radiation/dirichlet' )  THEN

       DO  i = nxl-1, nxr+1
          IF ( i <= outflow_damping_width )  THEN
             km_damp_x(i) = km_damp_max * MIN( 1.0,                    &
                            ( outflow_damping_width - i ) /            &
                            REAL( outflow_damping_width/2 )            &
                                             )
          ELSE
             km_damp_x(i) = 0.0
          ENDIF
       ENDDO

    ENDIF

    IF ( bc_ns == 'dirichlet/radiation' )  THEN

       DO  j = nys-1, nyn+1
          IF ( j >= ny - outflow_damping_width )  THEN
             km_damp_y(j) = km_damp_max * MIN( 1.0,                    &
                            ( j - ( ny - outflow_damping_width ) ) /   &
                            REAL( outflow_damping_width/2 )            &
                                             )
          ELSE
             km_damp_y(j) = 0.0
          ENDIF
       ENDDO

    ELSEIF ( bc_ns == 'radiation/dirichlet' )  THEN

       DO  j = nys-1, nyn+1
          IF ( j <= outflow_damping_width )  THEN
             km_damp_y(j) = km_damp_max * MIN( 1.0,                    &
                            ( outflow_damping_width - j ) /            &
                            REAL( outflow_damping_width/2 )            &
                                             )
          ELSE
             km_damp_y(j) = 0.0
          ENDIF
       ENDDO

    ENDIF

!
!-- Initialize local summation arrays for UP flow_statistics. This is necessary
!-- because they may not yet have been initialized when they are called from 
!-- flow_statistics (or - depending on the chosen model run - are never 
!-- initialized)
    sums_divnew_l      = 0.0
    sums_divold_l      = 0.0
    sums_l_l           = 0.0
    sums_up_fraction_l = 0.0
    sums_wsts_bc_l     = 0.0

!
!-- Pre-set masks for regional statistics. Default is the total model domain.
    rmask = 1.0

!
!-- User-defined initializing actions. Check afterwards, if maximum number
!-- of allowed timeseries is not exceeded
    CALL user_init

    IF ( dots_num > dots_max )  THEN
       IF ( myid == 0 )  THEN
          PRINT*, '+++ user_init: number of time series quantities exceeds', &
                  ' its maximum of dots_max = ', dots_max
          PRINT*, '    Please increase dots_max in modules.f90.'
       ENDIF
       CALL local_stop
    ENDIF

!
!-- Input binary data file is not needed anymore. This line must be placed
!-- after call of user_init!
    CALL close_file( 13 )

!
!-- Compute total sum of active mask grid points
!-- ngp_2dh: number of grid points of a horizontal cross section through the
!--          total domain
!-- ngp_3d:  number of grid points of the total domain
!-- Note: The lower vertical index nzb_s_outer imposes a small error on the 2D 
!-- ----  averages of staggered variables such as u and v due to the topography
!--       arrangement on the staggered grid. Maybe revise later.
    ngp_2dh_outer_l = 0
    ngp_2dh_outer   = 0
    ngp_2dh_l       = 0
    ngp_2dh         = 0
    ngp_3d_inner_l  = 0
    ngp_3d_inner    = 0
    ngp_3d          = 0
    ngp_sums        = ( nz + 2 ) * var_sum

    DO  sr = 0, statistic_regions
       DO  i = nxl, nxr
          DO  j = nys, nyn
             IF ( rmask(j,i,sr) == 1.0 )  THEN
!
!--             All xy-grid points
                ngp_2dh_l(sr) = ngp_2dh_l(sr) + 1
!
!--             xy-grid points above topography
                DO  k = nzb_s_outer(j,i), nz + 1
                   ngp_2dh_outer_l(k,sr) = ngp_2dh_outer_l(k,sr) + 1
                ENDDO
!
!--             All grid points of the total domain above topography
                ngp_3d_inner_l(sr) = ngp_3d_inner_l(sr) + &
                                     ( nz - nzb_s_inner(j,i) + 2 )
             ENDIF
          ENDDO
       ENDDO
    ENDDO

    sr = statistic_regions + 1
#if defined( __parallel )
    CALL MPI_ALLREDUCE( ngp_2dh_l(0), ngp_2dh(0), sr, MPI_INTEGER, MPI_SUM,  &
                        comm2d, ierr )
    CALL MPI_ALLREDUCE( ngp_2dh_outer_l(0,0), ngp_2dh_outer(0,0), (nz+2)*sr, &
                        MPI_INTEGER, MPI_SUM, comm2d, ierr )
    CALL MPI_ALLREDUCE( ngp_3d_inner_l(0), ngp_3d_inner(0), sr, MPI_INTEGER, &
                        MPI_SUM, comm2d, ierr )
#else
    ngp_2dh       = ngp_2dh_l
    ngp_2dh_outer = ngp_2dh_outer_l
    ngp_3d_inner  = ngp_3d_inner_l
#endif

    ngp_3d = ngp_2dh * ( nz + 2 )

!
!-- Set a lower limit of 1 in order to avoid zero divisions in flow_statistics,
!-- buoyancy, etc. A zero value will occur for cases where all grid points of
!-- the respective subdomain lie below the surface topography
    ngp_2dh_outer = MAX( 1, ngp_2dh_outer(:,:) ) 
    ngp_3d_inner  = MAX( 1, ngp_3d_inner(:)    )

    DEALLOCATE( ngp_2dh_l, ngp_2dh_outer_l, ngp_3d_inner_l )


 END SUBROUTINE init_3d_model