MODULE trcsed
   !!======================================================================
   !!                         ***  MODULE p4sed  ***
   !! TOP :   PISCES Compute loss of organic matter in the sediments
   !!======================================================================
   !! History :    -   !  1995-06 (M. Levy)  original code
   !!              -   !  2000-12 (E. Kestenare)  clean up
   !!             2.0  !  2007-12  (C. Deltel, G. Madec)  F90 + simplifications
   !!----------------------------------------------------------------------
#if defined key_lobster
   !!----------------------------------------------------------------------
   !!   'key_lobster'                                     LOBSTER bio-model
   !!----------------------------------------------------------------------
   !!   trc_sed        :  Compute loss of organic matter in the sediments
   !!----------------------------------------------------------------------
   USE oce_trc         !
   USE trc
   USE sms_lobster
   USE lbclnk
   USE trdmod_oce
   USE trdmod_trc
   USE iom
   USE prtctl_trc      ! Print control for debbuging

   IMPLICIT NONE
   PRIVATE

   PUBLIC   trc_sed    ! called in ???

   !!* Substitution
#  include "top_substitute.h90"
   !!----------------------------------------------------------------------
   !! NEMO/TOP 3.3 , NEMO Consortium (2010)
   !! $Id$
   !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt)
   !!----------------------------------------------------------------------

CONTAINS

   SUBROUTINE trc_sed( kt )
      !!---------------------------------------------------------------------
      !!                     ***  ROUTINE trc_sed  ***
      !!
      !! ** Purpose :   compute the now trend due to the vertical sedimentation of
      !!              detritus and add it to the general trend of detritus equations
      !!
      !! ** Method  :   this ROUTINE compute not exactly the advection but the
      !!              transport term, i.e.  dz(wt) and dz(ws)., dz(wtr)
      !!              using an upstream scheme
      !!              the now vertical advection of tracers is given by:
      !!                      dz(trn wn) = 1/bt dk+1( e1t e2t vsed (trn) )
      !!              add this trend now to the general trend of tracer (ta,sa,tra):
      !!                             tra = tra + dz(trn wn)
      !!        
      !!              IF 'key_diabio' is defined, the now vertical advection
      !!              trend of passive tracers is saved for futher diagnostics.
      !!---------------------------------------------------------------------
      !!
      INTEGER, INTENT( in ) ::   kt      ! ocean time-step index      
      !!
      INTEGER  ::   ji, jj, jk, jl, ierr
      CHARACTER (len=25) :: charout
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zw2d
      REAL(wp), POINTER, DIMENSION(:,:,:) :: zwork, ztra, ztrbio
      !!---------------------------------------------------------------------
      !
      IF( nn_timing == 1 )  CALL timing_start('trc_sed')
      !
      IF( kt == nittrc000 ) THEN
         IF(lwp) WRITE(numout,*)
         IF(lwp) WRITE(numout,*) ' trc_sed: LOBSTER sedimentation'
         IF(lwp) WRITE(numout,*) ' ~~~~~~~'
      ENDIF

      ! Allocate temporary workspace
      CALL wrk_alloc( jpi, jpj, jpk, zwork, ztra )

      IF( ln_diatrc )  THEN
         CALL wrk_alloc( jpi, jpj, zw2d )
      ENDIF

      IF( l_trdtrc ) THEN
         CALL wrk_alloc( jpi, jpj, jpk, ztrbio )
         ztrbio(:,:,:) = tra(:,:,:,jp_lob_det)
      ENDIF

      ! sedimentation of detritus  : upstream scheme
      ! --------------------------------------------

      ! for detritus sedimentation only - jp_lob_det
      zwork(:,:,1  ) = 0.e0      ! surface value set to zero
      zwork(:,:,jpk) = 0.e0      ! bottom value  set to zero

      ! tracer flux at w-point: we use -vsed (downward flux)  with simplification : no e1*e2
      DO jk = 2, jpkm1
         zwork(:,:,jk) = -vsed * trn(:,:,jk-1,jp_lob_det)
      END DO

      ! tracer flux divergence at t-point added to the general trend
      DO jk = 1, jpkm1
         DO jj = 1, jpj
            DO ji = 1, jpi
               ztra(ji,jj,jk)  = - ( zwork(ji,jj,jk) - zwork(ji,jj,jk+1) ) / fse3t(ji,jj,jk)
               tra(ji,jj,jk,jp_lob_det) = tra(ji,jj,jk,jp_lob_det) + ztra(ji,jj,jk) 
            END DO
         END DO
      END DO

      IF( ln_diatrc ) THEN 
         DO jk = 1, jpkm1
            DO jj = 1, jpj
               DO ji = 1, jpi
                  zw2d(ji,jj) = zw2d(ji,jj) + ztra(ji,jj,jk) * fse3t(ji,jj,jk) * 86400.
               END DO
            END DO
         END DO
         IF( lk_iomput )  THEN
           CALL iom_put( "TDETSED", zw2d )
         ELSE
           trc2d(:,:,jp_lob0_2d + 7) = zw2d(:,:)
         ENDIF
         CALL wrk_dealloc( jpi, jpj, zw2d )
      ENDIF
      !
      IF( ln_diabio )  trbio(:,:,:,jp_lob0_trd + 7) = ztra(:,:,:)
      CALL wrk_dealloc( jpi, jpj, jpk, zwork, ztra )
      !
      IF( l_trdtrc ) THEN
         ztrbio(:,:,:) = tra(:,:,:,jp_lob_det) - ztrbio(:,:,:)
         jl = jp_lob0_trd + 7
         CALL trd_mod_trc( ztrbio, jl, kt )   ! handle the trend
         CALL wrk_dealloc( jpi, jpj, jpk, ztrbio )
      ENDIF

      IF(ln_ctl)   THEN  ! print mean trends (used for debugging)
         WRITE(charout, FMT="('sed')")
         CALL prt_ctl_trc_info(charout)
         CALL prt_ctl_trc(tab4d=tra, mask=tmask, clinfo=ctrcnm)
      ENDIF
      !
      IF( nn_timing == 1 )  CALL timing_stop('trc_sed')
      !
   END SUBROUTINE trc_sed

#else
   !!======================================================================
   !!  Dummy module :                                   No PISCES bio-model
   !!======================================================================
CONTAINS
   SUBROUTINE trc_sed( kt )                   ! Empty routine
      INTEGER, INTENT( in ) ::   kt
      WRITE(*,*) 'trc_sed: You should not have seen this print! error?', kt
   END SUBROUTINE trc_sed
#endif 

   !!======================================================================
END MODULE  trcsed