source: palm/trunk/SOURCE/user_interface.f90 @ 88

 MODULE user

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! Calculation and output of user-defined profiles: new routine
! user_check_data_output_pr, +data_output_pr_user, max_pr_user in userpar,
! routine user_statistics has got two more arguments
! Bugfix: field_chr renamed field_char
!
! Former revisions:
! -----------------
! $Id: user_interface.f90 87 2007-05-22 15:46:47Z raasch $
!
! 60 2007-03-11 11:50:04Z raasch
! New routine user_init_3d_model which allows the initial setting of all 3d
! arrays under control of the user, new routine user_advec_particles,
! routine user_statistics now has one argument (sr),
! sample for generating time series quantities added
! Bugfix in sample for reading user defined data from restart file (user_init)
!
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.18  2006/06/02 15:25:00  raasch
! +change of grid-defining arguments in routine user_define_netcdf_grid,
! new argument "found" in user_data_output_2d and user_data_output_3d
!
! Revision 1.1  1998/03/24 15:29:04  raasch
! Initial revision
!
!
! Description:
! ------------
! Declaration of user-defined variables. This module may only be used
! in the user-defined routines (contained in user_interface.f90).
!------------------------------------------------------------------------------!

    INTEGER ::  user_idummy
    LOGICAL ::  user_defined_namelist_found = .FALSE.
    REAL    ::  user_dummy

!
!-- Sample for user-defined output
!    REAL, DIMENSION(:,:,:), ALLOCATABLE ::  u2, u2_av

    SAVE

 END MODULE user


 SUBROUTINE user_parin

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Interface to read user-defined namelist-parameters.
!------------------------------------------------------------------------------!

    USE control_parameters
    USE pegrid
    USE statistics
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=80) ::  zeile

    INTEGER ::  i, j


    NAMELIST /userpar/  data_output_pr_user, data_output_user, max_pr_user, &
                        region

!
!-- Position the namelist-file at the beginning (it was already opened in
!-- parin), search for user-defined namelist-group ("userpar", but any other
!-- name can be choosed) and position the file at this line.
    REWIND ( 11 )

    zeile = ' '
    DO   WHILE ( INDEX( zeile, '&userpar' ) == 0 )
       READ ( 11, '(A)', END=100 )  zeile
    ENDDO
    BACKSPACE ( 11 )

!
!-- Read user-defined namelist
    READ ( 11, userpar )
    user_defined_namelist_found = .TRUE.

!
!-- Determine the maximum number of user-profiles allowed to be calculated.
!-- This number may be (much) larger than num_user_profiles which only gives
!-- the number of user-defined profiles to be output.
    IF ( data_output_pr_user(1) /= ' '  .AND.  max_pr_user == 0 )  THEN
       max_pr_user = 100
    ENDIF

!
!-- Determine the number of user-defined profiles and append them to the
!-- standard data output (data_output_pr)
    IF ( data_output_pr_user(1) /= ' ' )  THEN
       i = 1
       DO  WHILE ( data_output_pr(i) /= ' '  .AND.  i <= 100 )
          i = i + 1
       ENDDO
       j = 1
       DO  WHILE ( data_output_pr_user(j) /= ' '  .AND.  j <= 100 )
          data_output_pr(i) = data_output_pr_user(j)
          num_user_profiles = num_user_profiles + 1
          i = i + 1
          j = j + 1
       ENDDO
    ENDIF

    IF ( num_user_profiles > max_pr_user )  THEN
       IF ( myid == 0 )  THEN
          PRINT*, '+++ user_parin: number of user-defined profiles given by '
          PRINT*, '                data_output_pr_user (', num_user_profiles, &
                                   ') is larger than the allowed maximum'
          PRINT*, '                number of profiles: max_pr_user(', &
                                   max_pr_user, ')'
       ENDIF
       CALL local_stop
    ENDIF

100 RETURN

 END SUBROUTINE user_parin



 SUBROUTINE user_header( io )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Print a header with user-defined informations.
!------------------------------------------------------------------------------!

    USE statistics
    USE user

    IMPLICIT NONE

    INTEGER ::  i, io

!
!-- If no user-defined variables are read from the namelist-file, no
!-- informations will be printed.
    IF ( .NOT. user_defined_namelist_found )  THEN
       WRITE ( io, 100 )
       RETURN
    ENDIF

!
!-- Printing the informations.
    WRITE ( io, 110 )

    IF ( statistic_regions /= 0 )  THEN
       WRITE ( io, 200 )
       DO  i = 0, statistic_regions
          WRITE ( io, 201 )  i, region(i)
       ENDDO
    ENDIF



!
!-- Format-descriptors
100 FORMAT (//' *** no user-defined variables found'/)
110 FORMAT (//1X,78('#')                                      &
            //' User-defined variables and actions:'/  &
              ' -----------------------------------'//)
200 FORMAT (' Output of profiles and time series for following regions:' /)
201 FORMAT (4X,'Region ',I1,':   ',A)


 END SUBROUTINE user_header



 SUBROUTINE user_init

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Execution of user-defined initializing actions
!------------------------------------------------------------------------------!

    USE control_parameters
    USE indices
    USE pegrid
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=20) :: field_char
!
!-- Here the user-defined initializing actions follow:
!-- Sample for user-defined output
!    ALLOCATE( u2(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
!
!    IF ( initializing_actions == 'read_restart_data' )  THEN
!       READ ( 13 )  field_char
!       DO  WHILE ( TRIM( field_char ) /= '*** end user ***' )
!
!          SELECT CASE ( TRIM( field_char ) )
!
!             CASE ( 'u2_av' )
!                ALLOCATE( u2_av(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
!                READ ( 13 )  u2_av
!
!             CASE DEFAULT
!                PRINT*, '+++ user_init: unknown variable named "', &
!                        TRIM( field_char ), '" found in'
!                PRINT*, '               data from prior run on PE ', myid
!                CALL local_stop
!
!          END SELECT
!
!          READ ( 13 )  field_char
!
!       ENDDO
!    ENDIF

!
!-- Sample for user-defined time series
!-- For each time series quantity you have to give a label and a unit,
!-- which will be used for the NetCDF file. They must not contain more than
!-- seven characters. The value of dots_num has to be increased by the
!-- number of new time series quantities. Its old value has to be store in
!-- dots_num_palm. See routine user_statistics on how to output calculate
!-- and output these quantities.
!    dots_label(dots_num+1) = 'abs_umx'
!    dots_unit(dots_num+1)  = 'm/s'
!    dots_label(dots_num+2) = 'abs_vmx'
!    dots_unit(dots_num+2)  = 'm/s'
!
!    dots_num_palm = dots_num
!    dots_num = dots_num + 2

 END SUBROUTINE user_init



 SUBROUTINE user_init_grid( nzb_local )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Execution of user-defined grid initializing actions
!------------------------------------------------------------------------------!

    USE control_parameters
    USE indices
    USE user

    IMPLICIT NONE

    INTEGER, DIMENSION(-1:ny+1,-1:nx+1) ::  nzb_local

!
!-- Here the user-defined grid initializing actions follow:

!
!-- Set the index array nzb_local for non-flat topography.
!-- Here consistency checks concerning domain size and periodicity are necessary
    SELECT CASE ( TRIM( topography ) )

       CASE ( 'flat', 'single_building' )
!
!--       Not allowed here since these are the standard cases used in init_grid.

       CASE ( 'user_defined_topography_1' )
!
!--       Here the user can define his own topography. After definition, please
!--       remove the following three lines!
          PRINT*, '+++ user_init_grid: topography "', &
               topography, '" not available yet'
          CALL local_stop

       CASE DEFAULT
!
!--       The DEFAULT case is reached if the parameter topography contains a
!--       wrong character string that is neither recognized in init_grid nor 
!--       here in user_init_grid.
          PRINT*, '+++ (user_)init_grid: unknown topography "', &
               topography, '"'
          CALL local_stop

    END SELECT


 END SUBROUTINE user_init_grid



 SUBROUTINE user_init_3d_model

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Allows the complete initialization of the 3d model.
!
! CAUTION: The user is responsible to set at least all those quantities which
! ------   are normally set within init_3d_model!
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE control_parameters
    USE indices
    USE user

    IMPLICIT NONE


 END SUBROUTINE user_init_3d_model



 MODULE user_actions_mod

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Execution of user-defined actions before or after single timesteps
!------------------------------------------------------------------------------!

    PRIVATE
    PUBLIC user_actions

    INTERFACE user_actions
       MODULE PROCEDURE user_actions
       MODULE PROCEDURE user_actions_ij
    END INTERFACE user_actions

 CONTAINS


!------------------------------------------------------------------------------!
! Call for all grid points
!------------------------------------------------------------------------------!
    SUBROUTINE user_actions( location )

       USE control_parameters
       USE cpulog
       USE indices
       USE interfaces
       USE pegrid
       USE user
       USE arrays_3d

       IMPLICIT NONE

       CHARACTER (LEN=*) ::  location

       INTEGER ::  i, j, k

       CALL cpu_log( log_point(24), 'user_actions', 'start' )

!
!--    Here the user-defined actions follow
!--    No calls for single grid points are allowed at locations before and
!--    after the timestep, since these calls are not within an i,j-loop
       SELECT CASE ( location )

          CASE ( 'before_timestep' )
!
!--          Enter actions to be done before every timestep here


          CASE ( 'after_integration' )
!
!--          Enter actions to be done after every time integration (before
!--          data output)
!--          Sample for user-defined output:
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nzt+1
!                      u2(k,j,i) = u(k,j,i)**2
!                   ENDDO
!                ENDDO
!             ENDDO


          CASE ( 'after_timestep' )
!
!--          Enter actions to be done after every timestep here


          CASE ( 'u-tendency' )
!
!--          Enter actions to be done in the u-tendency term here


          CASE ( 'v-tendency' )


          CASE ( 'w-tendency' )


          CASE ( 'pt-tendency' )


          CASE ( 'e-tendency' )


          CASE ( 'q-tendency' )


          CASE DEFAULT
             IF ( myid == 0 )  PRINT*, '+++ user_actions: unknown location "', &
                                       location, '"'
             CALL local_stop

       END SELECT

       CALL cpu_log( log_point(24), 'user_actions', 'stop' )

    END SUBROUTINE user_actions


!------------------------------------------------------------------------------!
! Call for grid point i,j
!------------------------------------------------------------------------------!
    SUBROUTINE user_actions_ij( i, j, location )

       USE control_parameters
       USE pegrid
       USE user

       IMPLICIT NONE

       CHARACTER (LEN=*) ::  location

       INTEGER ::  i, idum, j


!
!--    Here the user-defined actions follow
       SELECT CASE ( location )

          CASE ( 'u-tendency' )
!
!--          Enter actions to be done in the u-tendency term here


          CASE ( 'v-tendency' )


          CASE ( 'w-tendency' )


          CASE ( 'pt-tendency' )


          CASE ( 'e-tendency' )


          CASE ( 'q-tendency' )


          CASE ( 'before_timestep', 'after_integration', 'after_timestep' )
             IF ( myid == 0 )  THEN
                PRINT*, '+++ user_actions: location "', location, '" is not ', &
                             'allowed to be called with parameters "i" and "j"'
             ENDIF
             CALL local_stop


          CASE DEFAULT
             IF ( myid == 0 )  PRINT*, '+++ user_actions: unknown location "', &
                                       location, '"'
             CALL local_stop


       END SELECT

    END SUBROUTINE user_actions_ij

 END MODULE user_actions_mod



 SUBROUTINE user_statistics( mode, sr, tn )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Calculation of user-defined statistics, i.e. horizontally averaged profiles
! and time series.
! This routine is called for every statistic region sr defined by the user,
! but at least for the region "total domain" (sr=0).
! See section 3.5.4 on how to define, calculate, and output user defined
! quantities.
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE indices
    USE statistics
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  mode

    INTEGER ::  i, j, k, sr, tn


    IF ( mode == 'profiles' )  THEN

!
!--    Sample on how to calculate horizontally averaged profiles of user-
!--    defined quantities. Each quantity is identified by the index
!--    "pr_palm+#" where "#" is an integer starting from 1. These
!--    user-profile-numbers must also be assigned to the respective strings
!--    given by data_output_pr_user in routine user_check_data_output_pr.
!       !$OMP DO
!       DO  i = nxl, nxr
!          DO  j = nys, nyn
!             DO  k = nzb_s_outer(j,i)+1, nzt
!!
!!--             Sample on how to calculate the profile for vertical velocity
!                sums_l(k,pr_palm+1,tn) = sums_l(k,pr_palm+1,tn) +       &
!                                                 w(k,j,i)               &
!                                                 * rmask(j,i,sr)
!!
!!--             Further profiles can be defined and calculated by increasing
!!--             the second index of array sums_l (replace ... appropriately)
!                sums_l(k,pr_palm+2,tn) = sums_l(k,pr_palm+2,tn) + ... &
!                                         * rmask(j,i,sr)
!             ENDDO
!          ENDDO
!       ENDDO

    ELSEIF ( mode == 'time_series' )  THEN

!
!--    Sample on how to add values for the user-defined time series quantities.
!--    These have to be defined before in routine user_init. This sample
!--    creates two time series for the absolut values of the horizontal
!--    velocities u and v.
!       ts_value(dots_num_palm+1,sr) = ABS( u_max )
!       ts_value(dots_num_palm+2,sr) = ABS( v_max )

    ENDIF

 END SUBROUTINE user_statistics



 SUBROUTINE user_last_actions

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Execution of user-defined actions at the end of a job.
!------------------------------------------------------------------------------!

    USE user

    IMPLICIT NONE

!
!-- Here the user-defined actions at the end of a job follow.
!-- Sample for user-defined output:
!    IF ( ALLOCATED( u2_av ) )  THEN
!       WRITE ( 14 )  'u2_av               ';  WRITE ( 14 )  u2_av
!    ENDIF

    WRITE ( 14 )  '*** end user ***    '

 END SUBROUTINE user_last_actions



 SUBROUTINE user_init_particles

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Modification of initial particles by the user.
!------------------------------------------------------------------------------!

    USE particle_attributes
    USE user

    IMPLICIT NONE

    INTEGER ::  n

!
!-- Here the user-defined actions follow
!    DO  n = 1, number_of_initial_particles
!    ENDDO

 END SUBROUTINE user_init_particles



 SUBROUTINE user_advec_particles

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Modification of initial particles by the user.
!------------------------------------------------------------------------------!

    USE particle_attributes
    USE user

    IMPLICIT NONE

    INTEGER ::  n

!
!-- Here the user-defined actions follow
!    DO  n = 1, number_of_initial_particles
!    ENDDO

 END SUBROUTINE user_advec_particles



 SUBROUTINE user_particle_attributes

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Define the actual particle attributes (size, colour) by the user.
!------------------------------------------------------------------------------!

    USE particle_attributes
    USE user

    IMPLICIT NONE

    INTEGER ::  n

!
!-- Here the user-defined actions follow
!    DO  n = 1, number_of_initial_particles
!    ENDDO

 END SUBROUTINE user_particle_attributes



 SUBROUTINE user_dvrp_coltab( mode, variable )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Definition of the colour table to be used by the dvrp software.
!------------------------------------------------------------------------------!

    USE dvrp_variables
    USE pegrid
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  mode
    CHARACTER (LEN=*) ::  variable


!
!-- Here the user-defined actions follow
    SELECT CASE ( mode )

       CASE ( 'particles' )

       CASE ( 'slicer' )

       CASE DEFAULT
          IF ( myid == 0 )  PRINT*, '+++ user_dvrp_coltab: unknown mode "', &
                                    mode, '"'
          CALL local_stop

    END SELECT

 END SUBROUTINE user_dvrp_coltab



 SUBROUTINE user_check_data_output( variable, unit )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Set the unit of user defined output quantities. For those variables
! not recognized by the user, the parameter unit is set to "illegal", which
! tells the calling routine that the output variable is not defined and leads
! to a program abort.
!------------------------------------------------------------------------------!

    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  unit, variable


    SELECT CASE ( TRIM( variable ) )

!
!--    Uncomment and extend the following lines, if necessary
!       CASE ( 'u2' )
!          unit = 'm2/s2'
!
       CASE DEFAULT
          unit = 'illegal'

    END SELECT


 END SUBROUTINE user_check_data_output



 SUBROUTINE user_check_data_output_pr( variable, var_count, unit )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Set the unit of user defined profile output quantities. For those variables
! not recognized by the user, the parameter unit is set to "illegal", which
! tells the calling routine that the output variable is not defined and leads
! to a program abort.
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE indices
    USE netcdf_control
    USE profil_parameter
    USE statistics
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  unit, variable

    INTEGER ::  index, var_count


    SELECT CASE ( TRIM( variable ) )

!
!--    Uncomment and extend the following lines, if necessary.
!--    Add additional CASE statements depending on the number of quantities
!--    for which profiles are to be calculated. The respective calculations
!--    to be performed have to be added in routine user_statistics.
!--    The quantities are (internally) identified by a user-profile-number
!--    (see variable "index" below). The first user-profile must be assigned
!--    the number "pr_palm+1", the second one "pr_palm+2", etc. The respective
!--    user-profile-numbers have also to be used in routine user_statistics!
!       CASE ( 'w_user' )                  ! quantity string as given in
!                                          ! data_output_pr_user
!          index = pr_palm + 1
!          dopr_index(var_count)  = index  ! the quantities' user-profile-number
!          dopr_unit(var_count)   = 'm/s'  ! quantity unit
!          hom(:,2,index,:)       = SPREAD( zw, 2, statistic_regions+1 )
!                                          ! grid on which the quantity is
!                                          ! defined (use zu or zw)

       CASE DEFAULT
          unit = 'illegal'

    END SELECT


 END SUBROUTINE user_check_data_output_pr



 SUBROUTINE user_define_netcdf_grid( variable, found, grid_x, grid_y, grid_z )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Set the grids on which user-defined output quantities are defined.
! Allowed values for grid_x are "x" and "xu", for grid_y "y" and "yv", and
! for grid_z "zu" and "zw".
!------------------------------------------------------------------------------!

    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  grid_x, grid_y, grid_z, variable

    LOGICAL ::  found


    SELECT CASE ( TRIM( variable ) )

!
!--    Uncomment and extend the following lines, if necessary
!       CASE ( 'u2', 'u2_xy', 'u2_xz', 'u2_yz' )
!          grid_x = 'xu'
!          grid_y = 'y'
!          grid_z = 'zu'

       CASE DEFAULT
          found  = .FALSE.
          grid_x = 'none'
          grid_y = 'none'
          grid_z = 'none'

    END SELECT


 END SUBROUTINE user_define_netcdf_grid



 SUBROUTINE user_data_output_2d( av, variable, found, grid, local_pf )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Resorts the user-defined output quantity with indices (k,j,i) to a
! temporary array with indices (i,j,k) and sets the grid on which it is defined.
! Allowed values for grid are "zu" and "zw".
!------------------------------------------------------------------------------!

    USE indices
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  grid, variable

    INTEGER ::  av, i, j, k

    LOGICAL ::  found

    REAL, DIMENSION(nxl-1:nxr+1,nys-1:nyn+1,nzb:nzt+1) ::  local_pf


    found = .TRUE.

    SELECT CASE ( TRIM( variable ) )

!
!--    Uncomment and extend the following lines, if necessary.
!--    The arrays for storing the user defined quantities (here u2 and u2_av)
!--    have to be declared and defined by the user!
!--    Sample for user-defined output:
!       CASE ( 'u2_xy', 'u2_xz', 'u2_yz' )
!          IF ( av == 0 )  THEN
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nzt+1
!                      local_pf(i,j,k) = u2(k,j,i)
!                   ENDDO
!                ENDDO
!             ENDDO
!          ELSE
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nzt+1
!                      local_pf(i,j,k) = u2_av(k,j,i)
!                   ENDDO
!                ENDDO
!             ENDDO
!          ENDIF
!
!          grid = 'zu'

       CASE DEFAULT
          found = .FALSE.
          grid  = 'none'

    END SELECT


 END SUBROUTINE user_data_output_2d



 SUBROUTINE user_data_output_3d( av, variable, found, local_pf, nz_do )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Resorts the user-defined output quantity with indices (k,j,i) to a
! temporary array with indices (i,j,k) and sets the grid on which it is defined.
! Allowed values for grid are "zu" and "zw".
!------------------------------------------------------------------------------!

    USE array_kind
    USE indices
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  variable

    INTEGER ::  av, i, j, k, nz_do

    LOGICAL ::  found

    REAL(spk), DIMENSION(nxl-1:nxr+1,nys-1:nyn+1,nzb:nz_do) ::  local_pf


    found = .TRUE.

    SELECT CASE ( TRIM( variable ) )

!
!--    Uncomment and extend the following lines, if necessary.
!--    The arrays for storing the user defined quantities (here u2 and u2_av)
!--    have to be declared and defined by the user!
!--    Sample for user-defined output:
!       CASE ( 'u2' )
!          IF ( av == 0 )  THEN
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nz_do
!                      local_pf(i,j,k) = u2(k,j,i)
!                   ENDDO
!                ENDDO
!             ENDDO
!          ELSE
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nz_do
!                      local_pf(i,j,k) = u2_av(k,j,i)
!                   ENDDO
!                ENDDO
!             ENDDO
!          ENDIF
!
!          grid = 'zu'

       CASE DEFAULT
          found = .FALSE.

    END SELECT


 END SUBROUTINE user_data_output_3d



 SUBROUTINE user_3d_data_averaging( mode, variable )

!------------------------------------------------------------------------------!
!
! Description:
! ------------
! Sum up and time-average user-defined output quantities as well as allocate
! the array necessary for storing the average.
!------------------------------------------------------------------------------!

    USE control_parameters
    USE indices
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  mode, variable

    INTEGER ::  i, j, k


    IF ( mode == 'allocate' )  THEN

       SELECT CASE ( TRIM( variable ) )

!
!--       Uncomment and extend the following lines, if necessary.
!--       The arrays for storing the user defined quantities (here u2_av) have
!--       to be declared and defined by the user!
!--       Sample for user-defined output:
!          CASE ( 'u2' )
!             IF ( .NOT. ALLOCATED( u2_av ) )  THEN
!                ALLOCATE( u2_av(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
!             ENDIF
!             u2_av = 0.0

          CASE DEFAULT
             CONTINUE

       END SELECT

    ELSEIF ( mode == 'sum' )  THEN

       SELECT CASE ( TRIM( variable ) )

!
!--       Uncomment and extend the following lines, if necessary.
!--       The arrays for storing the user defined quantities (here u2 and
!--       u2_av) have to be declared and defined by the user!
!--       Sample for user-defined output:
!          CASE ( 'u2' )
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nzt+1
!                      u2_av(k,j,i) = u2_av(k,j,i) + u2(k,j,i)
!                   ENDDO
!                ENDDO
!             ENDDO

          CASE DEFAULT
             CONTINUE

       END SELECT

    ELSEIF ( mode == 'average' )  THEN

       SELECT CASE ( TRIM( variable ) )

!
!--       Uncomment and extend the following lines, if necessary.
!--       The arrays for storing the user defined quantities (here u2_av) have
!--       to be declared and defined by the user!
!--       Sample for user-defined output:
!          CASE ( 'u2' )
!             DO  i = nxl-1, nxr+1
!                DO  j = nys-1, nyn+1
!                   DO  k = nzb, nzt+1
!                      u2_av(k,j,i) = u2_av(k,j,i) / REAL( average_count_3d )
!                   ENDDO
!                ENDDO
!             ENDDO

       END SELECT

    ENDIF


 END SUBROUTINE user_3d_data_averaging