SUBROUTINE callsedim(ngrid,nlay, ptimestep,
     $                pplev,zlev, pt,
     &                pq, pdqfi, pdqsed,pdqs_sed,nq,rfall)

      USE tracer_h

      IMPLICIT NONE

!==================================================================
!     
!     Purpose
!     -------
!     Calculates sedimentation of aerosols depending on their
!     density and radius.
!     
!     Authors
!     -------
!     F. Forget (1999)
!     Tracer generalisation by E. Millour (2009)
!     
!==================================================================

c-----------------------------------------------------------------------
c   declarations:
c   -------------

#include "dimensions.h"
#include "dimphys.h"
#include "comcstfi.h"
#include "callkeys.h"

c   arguments:
c   ----------

      INTEGER ngrid              ! number of horizontal grid points
      INTEGER nlay               ! number of atmospheric layers
      REAL ptimestep             ! physics time step (s)
      REAL pplev(ngrid,nlay+1)   ! pressure at inter-layers (Pa)
      REAL pt(ngrid,nlay)        ! temperature at mid-layer (K)
      REAL zlev(ngrid,nlay+1)    ! altitude at layer boundaries


c    Traceurs :
      integer nq             ! number of tracers
      real pq(ngrid,nlay,nq)  ! tracers (kg/kg)
      real pdqfi(ngrid,nlay,nq)  ! tendency before sedimentation (kg/kg.s-1)
      real pdqsed(ngrid,nlay,nq) ! tendency due to sedimentation (kg/kg.s-1)
      real pdqs_sed(ngrid,nq)    ! flux at surface (kg.m-2.s-1)
      
c   local:
c   ------

      INTEGER l,ig, iq

      real zqi(ngrid,nlayermx,nq) ! to locally store tracers
      real masse (ngrid,nlayermx) ! Layer mass (kg.m-2)
      real epaisseur (ngrid,nlayermx) ! Layer thickness (m)
      real wq(ngrid,nlayermx+1) ! displaced tracer mass (kg.m-2)
c      real dens(ngrid,nlayermx) ! Mean density of the ice part. accounting for dust core
      real rfall(ngrid,nlayermx)


      LOGICAL firstcall
      SAVE firstcall
      DATA firstcall/.true./

c    ** un petit test de coherence
c       --------------------------

      IF (firstcall) THEN
        firstcall=.false.
      ENDIF ! of IF (firstcall)
      
!=======================================================================
!     Preliminary calculation of the layer characteristics
!     (mass (kg.m-2), thickness (m), etc.

      do  l=1,nlay
        do ig=1, ngrid
          masse(ig,l)=(pplev(ig,l) - pplev(ig,l+1)) /g 
          epaisseur(ig,l)= zlev(ig,l+1) - zlev(ig,l)
        end do
      end do

!======================================================================
! Calculate the transport due to sedimentation for each tracer
! [This has been rearranged by L. Kerber to allow the sedimentation
!  of general tracers.]
 
      zqi(1:ngrid,1:nlay,1:nq) = 0.
      do iq=1,nq
       if((radius(iq).gt.1.e-9).and.(iq.ne.igcm_co2_ice)) then   
!         (no sedim for gases; co2_ice sedim is done elsewhere)      

! store locally updated tracers

          do l=1,nlay 
            do ig=1, ngrid
              zqi(ig,l,iq)=pq(ig,l,iq)+pdqfi(ig,l,iq)*ptimestep
            enddo
          enddo ! of do l=1,nlay
        
!======================================================================
! Sedimentation 
!======================================================================
! Water          
          if (water.and.(iq.eq.igcm_h2o_ice)) then
             call newsedim(ngrid,nlay,ngrid*nlay,ptimestep,
     &            pplev,masse,epaisseur,pt,rfall,rho_q(iq),zqi,wq)

! General Case
          else 
             call newsedim(ngrid,nlay,1,ptimestep,
     &            pplev,masse,epaisseur,pt,radius(iq),rho_q(iq),
     &            zqi,wq)
          endif

!=======================================================================
!     Calculate the tendencies
!======================================================================

          do ig=1,ngrid
!     Ehouarn: with new way of tracking tracers by name, this is simply
            pdqs_sed(ig,iq) = wq(ig,1)/ptimestep
          end do

          DO l = 1, nlay
            DO ig=1,ngrid
              pdqsed(ig,l,iq)=(zqi(ig,l,iq)-
     &        (pq(ig,l,iq) + pdqfi(ig,l,iq)*ptimestep))/ptimestep
            ENDDO
          ENDDO
       endif ! of no gases no co2_ice
      enddo ! of do iq=1,nq
      return
      end