SUBROUTINE user_spectra( mode, m, pr )

!------------------------------------------------------------------------------!
! Current revisions:
! -----------------
! Output of messages replaced by message handling routine. 
!
! Former revisions:
! -----------------
! $Id: user_spectra.f90 258 2009-03-13 12:36:03Z letzel $
!
! 211 2008-11-11 04:46:24Z raasch
! Former file user_interface.f90 split into one file per subroutine
!
! Description:
! ------------
! Calculation of user-defined spectra.
! See section 3.5.4 on how to define, calculate, and output user defined
! quantities.
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE control_parameters
    USE indices
    USE spectrum
    USE statistics
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  mode

    INTEGER ::  i, j, k, m, pr


!
!-- Sample on how to calculate spectra of user-defined quantities. 
!-- Each quantity is identified by the corresponding user profile 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.
    IF ( mode == 'preprocess' )  THEN

       SELECT CASE ( TRIM( data_output_sp(m) ) )
          
          CASE ( 'u', 'v', 'w', 'pt', 'q' )
!--          Not allowed here since these are the standard quantities used in 
!--          preprocess_spectra.
       
!          CASE ( 'u*v*' )
!             pr = pr_palm+1
!             d(nzb+1:nzt,nys:nyn,nxl:nxr) = ustvst(nzb+1:nzt,nys:nyn,nxl:nxr)
       
          CASE DEFAULT
             message_string = 'Spectra of ' // &
                              TRIM( data_output_sp(m) ) // ' can not be calculated'
             CALL message( 'user_spectra', 'UI0010', 0, 0, 0, 6, 0 )
            
       END SELECT

    ELSEIF ( mode == 'data_output' )  THEN

       SELECT CASE ( TRIM( data_output_sp(m) ) )

          CASE ( 'u', 'v', 'w', 'pt', 'q' )
!--          Not allowed here since these are the standard quantities used in 
!--          data_output_spectra.

!          CASE ( 'u*v*' )
!             pr = 6

          CASE DEFAULT
             message_string = 'Spectra of ' //  &
                              TRIM( data_output_sp(m) ) // ' are not defined'
             CALL message( 'user_spectra', 'UI0011', 0, 0, 0, 6, 0 )
             
          END SELECT

    ENDIF

 END SUBROUTINE user_spectra