SUBROUTINE user_init_grid( gls, nzb_local )

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! add 'single_street_canyon' as standard topography case
!
! Former revisions:
! -----------------
! $Id: user_init_grid.f90 240 2009-02-18 17:50:38Z heinze $
!
! 217 2008-12-09 18:00:48Z letzel
! +topography_grid_convention
! Former file user_interface.f90 split into one file per subroutine
!
! Description:
! ------------
! Execution of user-defined grid initializing actions
! First argument gls contains the number of ghost layers, which is > 1 if the
! multigrid method for the pressure solver is used
!------------------------------------------------------------------------------!

    USE control_parameters
    USE indices
    USE user

    IMPLICIT NONE

    INTEGER ::  gls

    INTEGER, DIMENSION(-gls:ny+gls,-gls:nx+gls) ::  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', 'single_street_canyon' )
!
!--       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. 

!
!--       For each user-defined topography, the topography grid convention has 
!--       to be explicitly set to either 'cell_edge' or 'cell_center'.
!--       topography_grid_convention = 'cell_edge'     ! OR:
!--       topography_grid_convention = 'cell_center'

!
!--       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