source: palm/trunk/SOURCE/init_3d_model.f90 @ 763

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

!------------------------------------------------------------------------------!
! Current revisions:
! ------------------
! 
!
! Former revisions:
! -----------------
! $Id: init_3d_model.f90 760 2011-09-15 14:37:54Z suehring $
!
! 759 2011-09-15 13:58:31Z raasch
! Splitting of parallel I/O in blocks of PEs
! Bugfix: No zero assignments to volume_flow_initial and volume_flow_area in
! case of normal restart runs.
!
! 713 2011-03-30 14:21:21Z suehring
! weight_substep and weight_pres are given as fractions.
!
! 709 2011-03-30 09:31:40Z raasch
! formatting adjustments
!
! 707 2011-03-29 11:39:40Z raasch
! p_sub renamed p_loc and allocated depending on the chosen pressure solver,
! initial assignments of zero to array p for iterative solvers only,
! bc_lr/ns replaced by bc_lr/ns_dirrad/raddir
!
! 680 2011-02-04 23:16:06Z gryschka
! bugfix: volume_flow_control
!
! 673 2011-01-18 16:19:48Z suehring 
! weight_substep (moved from advec_ws) and weight_pres added.
! Allocate p_sub when using Multigrid or SOR solver.
! Call of ws_init moved behind the if requests.
!
! 667 2010-12-23 12:06:00Z suehring/gryschka
! nxl-1, nxr+1, nys-1, nyn+1 replaced by nxlg, nxrg, nysg, nyng in loops and 
! allocation of arrays. Calls of exchange_horiz are modified.
! Call ws_init to initialize arrays needed for calculating statisticas and for
! optimization when ws-scheme is used.
! Initial volume flow is now calculated by using the variable hom_sum.
! Therefore the correction of initial volume flow for non-flat topography
! removed (removed u_nzb_p1_for_vfc and v_nzb_p1_for_vfc) 
! Changed surface boundary conditions for u and v in case of ibc_uv_b == 0 from
! mirror to Dirichlet boundary conditions (u=v=0), so that k=nzb is 
! representative for the height z0.
! Bugfix: type conversion of '1' to 64bit for the MAX function (ngp_3d_inner) 
!
! 622 2010-12-10 08:08:13Z raasch
! optional barriers included in order to speed up collective operations
!
! 560 2010-09-09 10:06:09Z weinreis
! bugfix: correction of calculating ngp_3d for 64 bit
!
! 485 2010-02-05 10:57:51Z raasch
! calculation of ngp_3d + ngp_3d_inner changed because they have now 64 bit
!
! 407 2009-12-01 15:01:15Z maronga
! var_ts is replaced by dots_max 
! Enabled passive scalar/humidity wall fluxes for non-flat topography
!
! 388 2009-09-23 09:40:33Z raasch
! Initialization of prho added.
! bugfix: correction of initial volume flow for non-flat topography
! bugfix: zero initialization of arrays within buildings for 'cyclic_fill'
! bugfix: avoid that ngp_2dh_s_inner becomes zero
! initializing_actions='read_data_for_recycling' renamed to 'cyclic_fill', now
! independent of turbulent_inflow
! Output of messages replaced by message handling routine.
! Set the starting level and the vertical smoothing factor used for 
! the external pressure gradient
! +conserve_volume_flow_mode: 'default', 'initial_profiles', 'inflow_profile'
! and 'bulk_velocity'
! If the inversion height calculated by the prerun is zero,
! inflow_damping_height must be explicitly specified.
!
! 181 2008-07-30 07:07:47Z raasch
! bugfix: zero assignments to tendency arrays in case of restarts,
! further extensions and modifications in the initialisation of the plant 
! canopy model,
! allocation of hom_sum moved to parin, initialization of spectrum_x|y directly
! after allocating theses arrays,
! read data for recycling added as new initialization option,
! dummy allocation for diss
!
! 138 2007-11-28 10:03:58Z letzel
! New counter ngp_2dh_s_inner.
! Allow new case bc_uv_t = 'dirichlet_0' for channel flow.
! Corrected calculation of initial volume flow for 'set_1d-model_profiles' and
! 'set_constant_profiles' in case of buildings in the reference cross-sections.
!
! 108 2007-08-24 15:10:38Z letzel
! Flux initialization in case of coupled runs, +momentum fluxes at top boundary,
! +arrays for phase speed c_u, c_v, c_w, indices for u|v|w_m_l|r changed
! +qswst_remote in case of atmosphere model with humidity coupled to ocean
! Rayleigh damping for ocean, optionally calculate km and kh from initial
! TKE e_init
!
! 97 2007-06-21 08:23:15Z raasch
! Initialization of salinity, call of init_ocean
!
! 87 2007-05-22 15:46:47Z raasch
! var_hom and var_sum renamed pr_palm
!
! 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 advec_ws
    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, ind_array(1), j, k, sr

    INTEGER, DIMENSION(:), ALLOCATABLE ::  ngp_2dh_l

    INTEGER, DIMENSION(:,:), ALLOCATABLE ::  ngp_2dh_outer_l,  &
         ngp_2dh_s_inner_l

    REAL ::  a, b

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

    REAL, DIMENSION(:), ALLOCATABLE ::  ngp_3d_inner_l, ngp_3d_inner_tmp


!
!-- 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),                          &
              ngp_3d_inner_tmp(0:statistic_regions),                        &
              sums_divnew_l(0:statistic_regions),                           &
              sums_divold_l(0:statistic_regions) )
    ALLOCATE( dp_smooth_factor(nzb:nzt), rdf(nzb+1:nzt) )
    ALLOCATE( ngp_2dh_outer(nzb:nzt+1,0:statistic_regions),                 &
              ngp_2dh_outer_l(nzb:nzt+1,0:statistic_regions),               &
              ngp_2dh_s_inner(nzb:nzt+1,0:statistic_regions),               &
              ngp_2dh_s_inner_l(nzb:nzt+1,0:statistic_regions),             &
              rmask(nysg:nyng,nxlg:nxrg,0:statistic_regions),           &
              sums(nzb:nzt+1,pr_palm+max_pr_user),                          &
              sums_l(nzb:nzt+1,pr_palm+max_pr_user,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(dots_max,0:statistic_regions) )
    ALLOCATE( km_damp_x(nxlg:nxrg), km_damp_y(nysg:nyng) )

    ALLOCATE( rif_1(nysg:nyng,nxlg:nxrg), shf_1(nysg:nyng,nxlg:nxrg), &
              ts(nysg:nyng,nxlg:nxrg), tswst_1(nysg:nyng,nxlg:nxrg),  &
              us(nysg:nyng,nxlg:nxrg), usws_1(nysg:nyng,nxlg:nxrg),   &
              uswst_1(nysg:nyng,nxlg:nxrg),                               &
              vsws_1(nysg:nyng,nxlg:nxrg),                                &
              vswst_1(nysg:nyng,nxlg:nxrg), z0(nysg:nyng,nxlg:nxrg) )

    IF ( timestep_scheme(1:5) /= 'runge' )  THEN
!
!--    Leapfrog scheme needs two timelevels of diffusion quantities
       ALLOCATE( rif_2(nysg:nyng,nxlg:nxrg),   &
                 shf_2(nysg:nyng,nxlg:nxrg),   &
                 tswst_2(nysg:nyng,nxlg:nxrg), &
                 usws_2(nysg:nyng,nxlg:nxrg),  &
                 uswst_2(nysg:nyng,nxlg:nxrg), &
                 vswst_2(nysg:nyng,nxlg:nxrg), &
                 vsws_2(nysg:nyng,nxlg:nxrg) )
    ENDIF

    ALLOCATE( d(nzb+1:nzta,nys:nyna,nxl:nxra),         &
              e_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              e_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              e_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              kh_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              km_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              p(nzb:nzt+1,nysg:nyng,nxlg:nxrg),    &
              pt_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              pt_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              pt_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              tend(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              u_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              u_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              u_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              v_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              v_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              v_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
              w_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              w_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
              w_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
!
!-- Following array is required for perturbation pressure within the iterative
!-- pressure solvers. For the multistep schemes (Runge-Kutta), array p holds
!-- the weighted average of the substeps and cannot be used in the Poisson
!-- solver.
    IF ( psolver == 'sor' )  THEN
       ALLOCATE( p_loc(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
    ELSEIF ( psolver == 'multigrid' )  THEN
!
!--    For performance reasons, multigrid is using one ghost layer only
       ALLOCATE( p_loc(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
    ENDIF

    IF ( timestep_scheme(1:5) /= 'runge' )  THEN
       ALLOCATE( kh_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                 km_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
    ENDIF

    IF ( humidity  .OR.  passive_scalar ) THEN
!
!--    2D-humidity/scalar arrays
       ALLOCATE ( qs(nysg:nyng,nxlg:nxrg),     &
                  qsws_1(nysg:nyng,nxlg:nxrg), &
                  qswst_1(nysg:nyng,nxlg:nxrg) )

       IF ( timestep_scheme(1:5) /= 'runge' )  THEN
          ALLOCATE( qsws_2(nysg:nyng,nxlg:nxrg), &
                    qswst_2(nysg:nyng,nxlg:nxrg) )
       ENDIF
!
!--    3D-humidity/scalar arrays
       ALLOCATE( q_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                 q_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                 q_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )

!
!--    3D-arrays needed for humidity only
       IF ( humidity )  THEN
          ALLOCATE( vpt_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )

          IF ( timestep_scheme(1:5) /= 'runge' )  THEN
             ALLOCATE( vpt_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
          ENDIF

          IF ( cloud_physics ) THEN
!
!--          Liquid water content
             ALLOCATE ( ql_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
!
!--          Precipitation amount and rate (only needed if output is switched)
             ALLOCATE( precipitation_amount(nysg:nyng,nxlg:nxrg), &
                       precipitation_rate(nysg:nyng,nxlg:nxrg) )
          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,nysg:nyng,nxlg:nxrg), &
                        ql_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                        ql_v(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                        ql_vp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
          ENDIF

       ENDIF

    ENDIF

    IF ( ocean )  THEN
       ALLOCATE( saswsb_1(nysg:nyng,nxlg:nxrg), &
                 saswst_1(nysg:nyng,nxlg:nxrg) )
       ALLOCATE( prho_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
                 rho_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
                 sa_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg),   &
                 sa_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg),   &
                 sa_3(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
       prho => prho_1
       rho  => rho_1  ! routines calc_mean_profile and diffusion_e require
                      ! density to be apointer
       IF ( humidity_remote )  THEN
          ALLOCATE( qswst_remote(nysg:nyng,nxlg:nxrg))
          qswst_remote = 0.0
       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,nysg:nyng,nxlg:nxrg) )
    ELSE
       ALLOCATE ( diss(2,2,2) )  ! required because diss is used as a
                                 ! formal parameter
    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 ) )
       spectrum_x = 0.0
       spectrum_y = 0.0
    ENDIF

!
!-- 3D-arrays for the leaf area density and the canopy drag coefficient
    IF ( plant_canopy ) THEN
       ALLOCATE ( lad_s(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
                  lad_u(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
                  lad_v(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
                  lad_w(nzb:nzt+1,nysg:nyng,nxlg:nxrg),  &
                  cdc(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )

       IF ( passive_scalar ) THEN
          ALLOCATE ( sls(nzb:nzt+1,nysg:nyng,nxlg:nxrg),   &
                     sec(nzb:nzt+1,nysg:nyng,nxlg:nxrg) ) 
       ENDIF

       IF ( cthf /= 0.0 ) THEN
          ALLOCATE ( lai(nzb:nzt+1,nysg:nyng,nxlg:nxrg),   &
                     canopy_heat_flux(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
       ENDIF

    ENDIF

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

!
!-- Arrays to store velocity data from t-dt and the phase speeds which
!-- are needed for radiation boundary conditions
    IF ( outflow_l )  THEN
       ALLOCATE( u_m_l(nzb:nzt+1,nysg:nyng,1:2), &
                 v_m_l(nzb:nzt+1,nysg:nyng,0:1), &
                 w_m_l(nzb:nzt+1,nysg:nyng,0:1) )
    ENDIF
    IF ( outflow_r )  THEN
       ALLOCATE( u_m_r(nzb:nzt+1,nysg:nyng,nx-1:nx), &
                 v_m_r(nzb:nzt+1,nysg:nyng,nx-1:nx), &
                 w_m_r(nzb:nzt+1,nysg:nyng,nx-1:nx) )
    ENDIF
    IF ( outflow_l  .OR.  outflow_r )  THEN
       ALLOCATE( c_u(nzb:nzt+1,nysg:nyng), c_v(nzb:nzt+1,nysg:nyng), &
                 c_w(nzb:nzt+1,nysg:nyng) )
    ENDIF
    IF ( outflow_s )  THEN
       ALLOCATE( u_m_s(nzb:nzt+1,0:1,nxlg:nxrg), &
                 v_m_s(nzb:nzt+1,1:2,nxlg:nxrg), &
                 w_m_s(nzb:nzt+1,0:1,nxlg:nxrg) )
    ENDIF
    IF ( outflow_n )  THEN
       ALLOCATE( u_m_n(nzb:nzt+1,ny-1:ny,nxlg:nxrg), &
                 v_m_n(nzb:nzt+1,ny-1:ny,nxlg:nxrg), &
                 w_m_n(nzb:nzt+1,ny-1:ny,nxlg:nxrg) )
    ENDIF
    IF ( outflow_s  .OR.  outflow_n )  THEN
       ALLOCATE( c_u(nzb:nzt+1,nxlg:nxrg), c_v(nzb:nzt+1,nxlg:nxrg), &
                 c_w(nzb:nzt+1,nxlg:nxrg) )
    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
       uswst_m => uswst_1;  uswst => uswst_2
       vsws_m  => vsws_1;   vsws  => vsws_2
       vswst_m => vswst_1;  vswst => vswst_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
       uswst => uswst_1
       vsws  => vsws_1
       vswst => vswst_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

       IF ( ocean )  THEN
          saswsb => saswsb_1
          saswst => saswst_1
          sa     => sa_1;    sa_p => sa_2;    tsa_m => sa_3
       ENDIF

    ENDIF
    
!
!-- Allocate arrays containing the RK coefficient for calculation of 
!-- perturbation pressure and turbulent fluxes. At this point values are
!-- set for pressure calculation during initialization (where no timestep
!-- is done). Further below the values needed within the timestep scheme
!-- will be set.
    ALLOCATE( weight_substep(1:intermediate_timestep_count_max), &
              weight_pres(1:intermediate_timestep_count_max) )
    weight_substep = 1.0
    weight_pres    = 1.0
    intermediate_timestep_count = 1  ! needed when simulated_time = 0.0
       
!
!-- Initialize model variables
    IF ( TRIM( initializing_actions ) /= 'read_restart_data'  .AND.  &
         TRIM( initializing_actions ) /= 'cyclic_fill' )  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 = nxlg, nxrg
             DO  j = nysg, nyng
                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 = nxlg, nxrg
                DO  j = nysg, nyng
                   q(:,j,i) = q_init
                ENDDO
             ENDDO
          ENDIF

          IF ( .NOT. constant_diffusion )  THEN
             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   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
          uswst = top_momentumflux_u
          vswst = top_momentumflux_v

!
!--       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.
!
!--           Following was removed, because mirror boundary condition are
!--           replaced by dirichlet boundary conditions 
!
!             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
             IF ( ibc_uv_b == 1 )  THEN
!
!--             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 = nxlg, nxrg
             DO  j = nysg, nyng
                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 = nxlg, nxrg
             DO  j = nysg, nyng
                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 ( humidity  .OR.  passive_scalar )  THEN
             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   q(:,j,i) = q_init
                ENDDO
             ENDDO
          ENDIF

          IF ( ocean )  THEN
             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   sa(:,j,i) = sa_init
                ENDDO
             ENDDO
          ENDIF
          
          IF ( constant_diffusion )  THEN
             km   = km_constant
             kh   = km / prandtl_number
             e    = 0.0
          ELSEIF ( e_init > 0.0 )  THEN
             DO  k = nzb+1, nzt
                km(k,:,:) = 0.1 * l_grid(k) * SQRT( e_init )
             ENDDO
             km(nzb,:,:)   = km(nzb+1,:,:)
             km(nzt+1,:,:) = km(nzt,:,:)
             kh   = km / prandtl_number
             e    = e_init
          ELSE
             IF ( .NOT. ocean )  THEN
                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
             ELSE
                kh   = 0.00001
                km   = 0.00001
             ENDIF
             e    = 0.0
          ENDIF
          rif   = 0.0
          ts    = 0.0
          us    = 0.0
          usws  = 0.0
          uswst = top_momentumflux_u
          vsws  = 0.0
          vswst = top_momentumflux_v
          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
!
!--    Bottom boundary
       IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2  )  THEN
          u(nzb,:,:) = 0.0
          v(nzb,:,:) = 0.0
       ENDIF

!
!--    Apply channel flow boundary condition
       IF ( TRIM( bc_uv_t ) == 'dirichlet_0' )  THEN

          u(nzt+1,:,:) = 0.0
          v(nzt+1,:,:) = 0.0

!--       For the Dirichlet condition to be correctly applied at the top, set
!--       ug and vg to zero there
          ug(nzt+1)    = 0.0
          vg(nzt+1)    = 0.0

       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 .OR. ibc_uv_b == 2)  THEN
          hom(nzb,1,5,:) = 0.0   
          hom(nzb,1,6,:) = 0.0  
       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 ( ocean )  THEN
!
!--       Store initial salinity profile
          hom(:,1,26,:)  = SPREAD( sa(:,nys,nxl), 2, statistic_regions+1 )
       ENDIF

       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 = nxlg, nxrg
                      DO  j = nysg, nyng
                         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
!
!--             Over topography surface_waterflux is replaced by 
!--             wall_humidityflux(0)
                IF ( TRIM( topography ) /= 'flat' )  THEN
                   wall_qflux = wall_humidityflux
                   DO  i = nxlg, nxrg
                      DO  j = nysg, nyng
                         IF ( nzb_s_inner(j,i) /= 0 )  THEN
                            qsws(j,i) = wall_qflux(0)
                         ENDIF
                      ENDDO
                   ENDDO
                ENDIF
                IF ( ASSOCIATED( qsws_m ) )  qsws_m = qsws
             ENDIF
          ENDIF

       ENDIF

!
!--    Initialize fluxes at top surface
!--    Currently, only the heatflux and salinity flux 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

             IF ( ocean )  THEN
                saswsb = bottom_salinityflux
                saswst = top_salinityflux
             ENDIF
          ENDIF

!
!--       Initialization in case of a coupled model run
          IF ( coupling_mode == 'ocean_to_atmosphere' )  THEN
             tswst = 0.0
             IF ( ASSOCIATED( tswst_m ) )  tswst_m = tswst
          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


!
!--    For the moment, vertical velocity is zero
       w = 0.0

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

!
!--    In case of iterative solvers, p must get an initial value
       IF ( psolver == 'multigrid'  .OR.  psolver == 'sor' )  p = 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 quantities for special advections schemes
       CALL init_advec

!
!--    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

!
!--    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

       IF ( ocean )  THEN
          tsa_m = 0.0
          sa_p  = sa
       ENDIF
       

    ELSEIF ( TRIM( initializing_actions ) == 'read_restart_data'  .OR.    &
         TRIM( initializing_actions ) == 'cyclic_fill' )  &
    THEN
!
!--    When reading data for cyclic fill of 3D prerun data, first read
!--    some of the global variables from restart file
       IF ( TRIM( initializing_actions ) == 'cyclic_fill' )  THEN

          DO  i = 0, io_blocks-1
             IF ( i == io_group )  THEN
                CALL read_parts_of_var_list
                CALL close_file( 13 )
             ENDIF
#if defined( __parallel )
             CALL MPI_BARRIER( comm2d, ierr )
#endif
          ENDDO

!
!--       Initialization of the turbulence recycling method
          IF ( turbulent_inflow )  THEN
!
!--          Store temporally and horizontally averaged vertical profiles to be
!--          used as mean inflow profiles
             ALLOCATE( mean_inflow_profiles(nzb:nzt+1,5) )

             mean_inflow_profiles(:,1) = hom_sum(:,1,0)    ! u
             mean_inflow_profiles(:,2) = hom_sum(:,2,0)    ! v
             mean_inflow_profiles(:,4) = hom_sum(:,4,0)    ! pt
             mean_inflow_profiles(:,5) = hom_sum(:,8,0)    ! e

!
!--          Use these mean profiles for the inflow (provided that Dirichlet
!--          conditions are used)
             IF ( inflow_l )  THEN
                DO  j = nysg, nyng
                   DO  k = nzb, nzt+1
                      u(k,j,nxlg:-1)  = mean_inflow_profiles(k,1)
                      v(k,j,nxlg:-1)  = mean_inflow_profiles(k,2)
                      w(k,j,nxlg:-1)  = 0.0
                      pt(k,j,nxlg:-1) = mean_inflow_profiles(k,4)
                      e(k,j,nxlg:-1)  = mean_inflow_profiles(k,5)
                   ENDDO
                ENDDO
             ENDIF

!
!--          Calculate the damping factors to be used at the inflow. For a
!--          turbulent inflow the turbulent fluctuations have to be limited
!--          vertically because otherwise the turbulent inflow layer will grow
!--          in time.
             IF ( inflow_damping_height == 9999999.9 )  THEN
!
!--             Default: use the inversion height calculated by the prerun; if
!--             this is zero, inflow_damping_height must be explicitly
!--             specified.
                IF ( hom_sum(nzb+6,pr_palm,0) /= 0.0 )  THEN
                   inflow_damping_height = hom_sum(nzb+6,pr_palm,0)
                ELSE
                   WRITE( message_string, * ) 'inflow_damping_height must be ',&
                        'explicitly specified because&the inversion height ', &
                        'calculated by the prerun is zero.'
                   CALL message( 'init_3d_model', 'PA0318', 1, 2, 0, 6, 0 )
                ENDIF

             ENDIF

             IF ( inflow_damping_width == 9999999.9 )  THEN
!
!--             Default for the transition range: one tenth of the undamped
!--             layer
                inflow_damping_width = 0.1 * inflow_damping_height

             ENDIF

             ALLOCATE( inflow_damping_factor(nzb:nzt+1) )

             DO  k = nzb, nzt+1

                IF ( zu(k) <= inflow_damping_height )  THEN
                   inflow_damping_factor(k) = 1.0
                ELSEIF ( zu(k) <= inflow_damping_height +  &
                                  inflow_damping_width )  THEN
                   inflow_damping_factor(k) = 1.0 -                            &
                                           ( zu(k) - inflow_damping_height ) / &
                                           inflow_damping_width
                ELSE
                   inflow_damping_factor(k) = 0.0
                ENDIF

             ENDDO
          ENDIF

       ENDIF

!
!--    Read binary data from restart file
       DO  i = 0, io_blocks-1
          IF ( i == io_group )  THEN
             CALL read_3d_binary
          ENDIF
#if defined( __parallel )
          CALL MPI_BARRIER( comm2d, ierr )
#endif
       ENDDO

!
!--    Inside buildings set velocities and TKE back to zero
       IF ( TRIM( initializing_actions ) == 'cyclic_fill' .AND.  &
            topography /= 'flat' )  THEN
!
!--       Inside buildings set velocities and TKE back to zero.
!--       Other scalars (pt, q, s, km, kh, p, sa, ...) are ignored at present,
!--       maybe revise later.
          IF ( timestep_scheme(1:5) == 'runge' )  THEN
             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   u  (nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v  (nzb:nzb_v_inner(j,i),j,i) = 0.0
                   w  (nzb:nzb_w_inner(j,i),j,i) = 0.0
                   e  (nzb:nzb_w_inner(j,i),j,i) = 0.0
                   u_m(nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v_m(nzb:nzb_v_inner(j,i),j,i) = 0.0
                   w_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   e_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   tu_m(nzb:nzb_u_inner(j,i),j,i) = 0.0
                   tv_m(nzb:nzb_v_inner(j,i),j,i) = 0.0
                   tw_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   te_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   tpt_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                ENDDO
             ENDDO
          ELSE
             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   u  (nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v  (nzb:nzb_v_inner(j,i),j,i) = 0.0
                   w  (nzb:nzb_w_inner(j,i),j,i) = 0.0
                   e  (nzb:nzb_w_inner(j,i),j,i) = 0.0
                   u_m(nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v_m(nzb:nzb_v_inner(j,i),j,i) = 0.0
                   w_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   e_m(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   u_p(nzb:nzb_u_inner(j,i),j,i) = 0.0
                   v_p(nzb:nzb_v_inner(j,i),j,i) = 0.0
                   w_p(nzb:nzb_w_inner(j,i),j,i) = 0.0
                   e_p(nzb:nzb_w_inner(j,i),j,i) = 0.0
                ENDDO
             ENDDO
          ENDIF

       ENDIF

!
!--    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
       IF ( ocean )  sa_p = sa

!
!--    Allthough tendency arrays are set in prognostic_equations, they have
!--    have to be predefined here because they are used (but multiplied with 0)
!--    there before they are set. 
       IF ( timestep_scheme(1:5) == 'runge' )  THEN
          te_m = 0.0; tpt_m = 0.0; tu_m = 0.0; tv_m = 0.0; tw_m = 0.0
          IF ( humidity  .OR.  passive_scalar )  tq_m = 0.0
          IF ( ocean )  tsa_m = 0.0
       ENDIF

    ELSE
!
!--    Actually this part of the programm should not be reached
       message_string = 'unknown initializing problem'
       CALL message( 'init_3d_model', 'PA0193', 1, 2, 0, 6, 0 )
    ENDIF


    IF (  TRIM( initializing_actions ) /= 'read_restart_data' )  THEN
!
!--    Initialize old timelevels needed for radiation boundary conditions
       IF ( outflow_l )  THEN
          u_m_l(:,:,:) = u(:,:,1:2)
          v_m_l(:,:,:) = v(:,:,0:1)
          w_m_l(:,:,:) = w(:,:,0:1)
       ENDIF
       IF ( outflow_r )  THEN
          u_m_r(:,:,:) = u(:,:,nx-1:nx)
          v_m_r(:,:,:) = v(:,:,nx-1:nx)
          w_m_r(:,:,:) = w(:,:,nx-1:nx)
       ENDIF
       IF ( outflow_s )  THEN
          u_m_s(:,:,:) = u(:,0:1,:)
          v_m_s(:,:,:) = v(:,1:2,:)
          w_m_s(:,:,:) = w(:,0:1,:)
       ENDIF
       IF ( outflow_n )  THEN
          u_m_n(:,:,:) = u(:,ny-1:ny,:)
          v_m_n(:,:,:) = v(:,ny-1:ny,:)
          w_m_n(:,:,:) = w(:,ny-1:ny,:)
       ENDIF
       
    ENDIF

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

       IF  ( TRIM( initializing_actions ) == 'cyclic_fill' )  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) + &
                                              hom_sum(k,1,0) * dzw(k)
                   volume_flow_area_l(1)    = volume_flow_area_l(1) + dzw(k)
                ENDDO
             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) + &
                                              hom_sum(k,2,0) * dzw(k)
                   volume_flow_area_l(2)    = volume_flow_area_l(2) + dzw(k)
                ENDDO
             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  

       ELSEIF ( TRIM( initializing_actions ) /= 'read_restart_data' )  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) * dzw(k)
                   volume_flow_area_l(1)    = volume_flow_area_l(1) + dzw(k)
                ENDDO
             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) * dzw(k)
                   volume_flow_area_l(2)    = volume_flow_area_l(2) + dzw(k)
                ENDDO
             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

!
!--    In case of 'bulk_velocity' mode, volume_flow_initial is calculated
!--    from u|v_bulk instead
       IF ( TRIM( conserve_volume_flow_mode ) == 'bulk_velocity' )  THEN
          volume_flow_initial(1) = u_bulk * volume_flow_area(1)
          volume_flow_initial(2) = v_bulk * volume_flow_area(2)
       ENDIF

    ENDIF


!
!-- Impose random perturbation on the horizontal velocity field and then
!-- remove the divergences from the velocity field at the initial stage
    IF ( create_disturbances .AND. &
         TRIM( initializing_actions ) /= 'read_restart_data'  .AND.  &
         TRIM( initializing_actions ) /= 'cyclic_fill' )  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

!
!-- Initialization of the leaf area density
    IF ( plant_canopy )  THEN
 
       SELECT CASE ( TRIM( canopy_mode ) )

          CASE( 'block' )

             DO  i = nxlg, nxrg
                DO  j = nysg, nyng
                   lad_s(:,j,i) = lad(:)
                   cdc(:,j,i)   = drag_coefficient
                   IF ( passive_scalar )  THEN
                      sls(:,j,i) = leaf_surface_concentration
                      sec(:,j,i) = scalar_exchange_coefficient
                   ENDIF
                ENDDO
             ENDDO

          CASE DEFAULT

!
!--          The DEFAULT case is reached either if the parameter 
!--          canopy mode contains a wrong character string or if the 
!--          user has coded a special case in the user interface. 
!--          There, the subroutine user_init_plant_canopy checks 
!--          which of these two conditions applies.
             CALL user_init_plant_canopy
 
          END SELECT

       CALL exchange_horiz( lad_s, nbgp )
       CALL exchange_horiz( cdc, nbgp )

       IF ( passive_scalar )  THEN
          CALL exchange_horiz( sls, nbgp )
          CALL exchange_horiz( sec, nbgp )
       ENDIF

!
!--    Sharp boundaries of the plant canopy in horizontal directions
!--    In vertical direction the interpolation is retained, as the leaf
!--    area density is initialised by prescribing a vertical profile 
!--    consisting of piecewise linear segments. The upper boundary 
!--    of the plant canopy is now defined by lad_w(pch_index,:,:) = 0.0.

       DO  i = nxl, nxr
          DO  j = nys, nyn
             DO  k = nzb, nzt+1 
                IF ( lad_s(k,j,i) > 0.0 )  THEN
                   lad_u(k,j,i)   = lad_s(k,j,i) 
                   lad_u(k,j,i+1) = lad_s(k,j,i)
                   lad_v(k,j,i)   = lad_s(k,j,i)
                   lad_v(k,j+1,i) = lad_s(k,j,i)
                ENDIF
             ENDDO
             DO  k = nzb, nzt
                lad_w(k,j,i) = 0.5 * ( lad_s(k+1,j,i) + lad_s(k,j,i) )
             ENDDO
          ENDDO
       ENDDO

       lad_w(pch_index,:,:) = 0.0
       lad_w(nzt+1,:,:)     = lad_w(nzt,:,:)

       CALL exchange_horiz( lad_u, nbgp )
       CALL exchange_horiz( lad_v, nbgp )
       CALL exchange_horiz( lad_w, nbgp )

!
!--    Initialisation of the canopy heat source distribution
       IF ( cthf /= 0.0 )  THEN
!
!--       Piecewise evaluation of the leaf area index by 
!--       integration of the leaf area density
          lai(:,:,:) = 0.0
          DO  i = nxlg, nxrg
             DO  j = nysg, nyng
                DO  k = pch_index-1, 0, -1
                   lai(k,j,i) = lai(k+1,j,i) +                   &
                                ( 0.5 * ( lad_w(k+1,j,i) +       &
                                          lad_s(k+1,j,i) ) *     &
                                  ( zw(k+1) - zu(k+1) ) )  +     &
                                ( 0.5 * ( lad_w(k,j,i)   +       &
                                          lad_s(k+1,j,i) ) *     &
                                  ( zu(k+1) - zw(k) ) )
                ENDDO
             ENDDO
          ENDDO

!
!--       Evaluation of the upward kinematic vertical heat flux within the 
!--       canopy
          DO  i = nxlg, nxrg
             DO  j = nysg, nyng
                DO  k = 0, pch_index
                   canopy_heat_flux(k,j,i) = cthf *                    &
                                             exp( -0.6 * lai(k,j,i) )
                ENDDO
             ENDDO
          ENDDO

!
!--       The near surface heat flux is derived from the heat flux 
!--       distribution within the canopy
          shf(:,:) = canopy_heat_flux(0,:,:)

          IF ( ASSOCIATED( shf_m ) )  shf_m = shf

       ENDIF

    ENDIF

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

    IF ( ocean )  THEN
!
!--    Initialize quantities needed for the ocean model
       CALL init_ocean

    ELSE
!
!--    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
    ENDIF

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

!
!-- Initialize the ws-scheme.    
    IF ( ws_scheme_sca .OR. ws_scheme_mom )  CALL ws_init        

!
!-- Setting weighting factors for calculation of perturbation pressure 
!-- and turbulent quantities from the RK substeps                
    IF ( TRIM(timestep_scheme) == 'runge-kutta-3' )  THEN      ! for RK3-method

       weight_substep(1) = 1./6.
       weight_substep(2) = 3./10.
       weight_substep(3) = 8./15.

       weight_pres(1)    = 1./3.
       weight_pres(2)    = 5./12.
       weight_pres(3)    = 1./4.

    ELSEIF ( TRIM(timestep_scheme) == 'runge-kutta-2' )  THEN  ! for RK2-method

       weight_substep(1) = 1./2.
       weight_substep(2) = 1./2.
          
       weight_pres(1)    = 1./2.
       weight_pres(2)    = 1./2.        

    ELSE                                     ! for Euler- and leapfrog-method

       weight_substep(1) = 1.0      
       weight_pres(1)    = 1.0                   

    ENDIF

!
!-- Initialize Rayleigh damping factors
    rdf = 0.0
    IF ( rayleigh_damping_factor /= 0.0 )  THEN
       IF ( .NOT. ocean )  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
       ELSE
          DO  k = nzt, nzb+1, -1
             IF ( zu(k) <= rayleigh_damping_height )  THEN
                rdf(k) = rayleigh_damping_factor * &
                      ( SIN( pi * 0.5 * ( rayleigh_damping_height - zu(k) )    &
                                      / ( rayleigh_damping_height - zu(nzb+1)))&
                      )**2
             ENDIF
          ENDDO
       ENDIF
    ENDIF

!
!-- Initialize the starting level and the vertical smoothing factor used for 
!-- the external pressure gradient
    dp_smooth_factor = 1.0
    IF ( dp_external )  THEN
!
!--    Set the starting level dp_level_ind_b only if it has not been set before
!--    (e.g. in init_grid).
       IF ( dp_level_ind_b == 0 )  THEN
          ind_array = MINLOC( ABS( dp_level_b - zu ) )
          dp_level_ind_b = ind_array(1) - 1 + nzb 
                                        ! MINLOC uses lower array bound 1
       ENDIF
       IF ( dp_smooth )  THEN
          dp_smooth_factor(:dp_level_ind_b) = 0.0
          DO  k = dp_level_ind_b+1, nzt
             dp_smooth_factor(k) = 0.5 * ( 1.0 + SIN( pi * &
                  ( REAL( k - dp_level_ind_b ) /  &
                    REAL( nzt - dp_level_ind_b ) - 0.5 ) ) )
          ENDDO
       ENDIF
    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_dirrad )  THEN

       DO  i = nxlg, nxrg
          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_raddir )  THEN

       DO  i = nxlg, nxrg
          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_dirrad )  THEN

       DO  j = nysg, nyng
          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_raddir )  THEN

       DO  j = nysg, nyng
          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 routine 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 exceeded
    CALL user_init

    IF ( dots_num > dots_max )  THEN
       WRITE( message_string, * ) 'number of time series quantities exceeds', &
                                  ' its maximum of dots_max = ', dots_max,    &
                                  ' &Please increase dots_max in modules.f90.'
       CALL message( 'init_3d_model', 'PA0194', 1, 2, 0, 6, 0 )    
    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
    ngp_2dh_outer_l   = 0
    ngp_2dh_outer     = 0
    ngp_2dh_s_inner_l = 0
    ngp_2dh_s_inner   = 0
    ngp_2dh_l         = 0
    ngp_2dh           = 0
    ngp_3d_inner_l    = 0.0
    ngp_3d_inner      = 0
    ngp_3d            = 0
    ngp_sums          = ( nz + 2 ) * ( pr_palm + max_pr_user )

    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
                DO  k = nzb_s_inner(j,i), nz + 1
                   ngp_2dh_s_inner_l(k,sr) = ngp_2dh_s_inner_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 )
    IF ( collective_wait )  CALL MPI_BARRIER( comm2d, ierr )
    CALL MPI_ALLREDUCE( ngp_2dh_l(0), ngp_2dh(0), sr, MPI_INTEGER, MPI_SUM,   &
                        comm2d, ierr )
    IF ( collective_wait )  CALL MPI_BARRIER( 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 )
    IF ( collective_wait )  CALL MPI_BARRIER( comm2d, ierr )
    CALL MPI_ALLREDUCE( ngp_2dh_s_inner_l(0,0), ngp_2dh_s_inner(0,0),         &
                        (nz+2)*sr, MPI_INTEGER, MPI_SUM, comm2d, ierr )
    IF ( collective_wait )  CALL MPI_BARRIER( comm2d, ierr )
    CALL MPI_ALLREDUCE( ngp_3d_inner_l(0), ngp_3d_inner_tmp(0), sr, MPI_REAL, &
                        MPI_SUM, comm2d, ierr )
    ngp_3d_inner = INT( ngp_3d_inner_tmp, KIND = SELECTED_INT_KIND( 18 ) )
#else
    ngp_2dh         = ngp_2dh_l
    ngp_2dh_outer   = ngp_2dh_outer_l
    ngp_2dh_s_inner = ngp_2dh_s_inner_l
    ngp_3d_inner    = INT( ngp_3d_inner_l, KIND = SELECTED_INT_KIND( 18 ) )
#endif

    ngp_3d = INT ( ngp_2dh, KIND = SELECTED_INT_KIND( 18 ) ) * &
             INT ( (nz + 2 ), KIND = SELECTED_INT_KIND( 18 ) )

!
!-- 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( INT(1, KIND = SELECTED_INT_KIND( 18 )),            &
                           ngp_3d_inner(:) )
    ngp_2dh_s_inner = MAX( 1, ngp_2dh_s_inner(:,:) ) 

    DEALLOCATE( ngp_2dh_l, ngp_2dh_outer_l, ngp_3d_inner_l, ngp_3d_inner_tmp )


 END SUBROUTINE init_3d_model