SUBROUTINE user_spectra( mode, m, pr )

!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2014 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
!  
!
! Former revisions:
! -----------------
! $Id: user_spectra.f90 1321 2014-03-20 09:40:40Z witha $
!
! 1320 2014-03-20 08:40:49Z raasch
! kind-parameters added to all INTEGER and REAL declaration statements, 
! kinds are defined in new module kinds, 
! old module precision_kind is removed,
! revision history before 2012 removed,
! comment fields (!:) to be used for variable explanations added to
! all variable declaration statements 
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 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 kinds
    
    USE spectrum
    
    USE statistics
    
    USE user

    IMPLICIT NONE

    CHARACTER (LEN=*) ::  mode

    INTEGER(iwp) ::  i    !: 
    INTEGER(iwp) ::  j    !: 
    INTEGER(iwp) ::  k    !: 
    INTEGER(iwp) ::  m    !: 
    INTEGER(iwp) ::  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