!
! $Header$
!
SUBROUTINE pentes_ini (q,w,masse,pbaru,pbarv,mode)
  USE comgeom2_mod_h
  USE comconst_mod, ONLY: pi, dtvr
  USE dimensions_mod, ONLY: iim, jjm, llm, ndm
  USE paramet_mod_h
IMPLICIT NONE

  !=======================================================================
  !   Adaptation LMDZ:  A.Armengaud (LGGE)
  !   ----------------
  !
  !   ********************************************************************
  !   Transport des traceurs par la methode des pentes
  !   ********************************************************************
  !   Reference possible : Russel. G.L., Lerner J.A.:
  !     A new Finite-Differencing Scheme for Traceur Transport
  !     Equation , Journal of Applied Meteorology, pp 1483-1498,dec. 81
  !   ********************************************************************
  !   q,w,masse,pbaru et pbarv
  !                  sont des arguments d'entree  pour le s-pg ....
  !
  !=======================================================================

  !   Arguments:
  !   ----------
  integer :: mode
  REAL :: pbaru( ip1jmp1,llm ),pbarv( ip1jm,llm )
  REAL :: q( iip1,jjp1,llm,0:3)
  REAL :: w( ip1jmp1,llm )
  REAL :: masse( iip1,jjp1,llm)
  !   Local:
  !   ------
  LOGICAL :: limit
  REAL :: sm ( iip1,jjp1, llm )
  REAL :: s0( iip1,jjp1,llm ),  sx( iip1,jjp1,llm )
  REAL :: sy( iip1,jjp1,llm ),  sz( iip1,jjp1,llm )
  real :: masn,mass,zz
  INTEGER :: i,j,l,iq

  !  modif Fred 24 03 96

  real :: sinlon(iip1),sinlondlon(iip1)
  real :: coslon(iip1),coslondlon(iip1)
  save sinlon,coslon,sinlondlon,coslondlon
  real :: dyn1,dyn2,dys1,dys2
  real :: qpn,qps,dqzpn,dqzps
  real :: smn,sms,s0n,s0s,sxn(iip1),sxs(iip1)
  real :: qmin,zq,pente_max
  !
  REAL :: SSUM
  integer :: ismax,ismin,lati,latf
  EXTERNAL  SSUM, ismin,ismax
  logical :: first
  save first
  !   fin modif

   ! EXTERNAL masskg
  EXTERNAL advx
  EXTERNAL advy
  EXTERNAL advz

  !  modif Fred 24 03 96
  data first/.true./

  limit = .TRUE.
  pente_max=2
  ! if (mode.eq.1.or.mode.eq.3) then
  ! if (mode.eq.1) then
  if (mode.ge.1) then
    lati=2
    latf=jjm
  else
    lati=1
    latf=jjp1
  endif

  qmin=0.4995
  qmin=0.
  if(first) then
     print*,'SCHEMA AMONT NOUVEAU'
     first=.false.
     do i=2,iip1
        coslon(i)=cos(rlonv(i))
        sinlon(i)=sin(rlonv(i))
        coslondlon(i)=coslon(i)*(rlonu(i)-rlonu(i-1))/pi
        sinlondlon(i)=sinlon(i)*(rlonu(i)-rlonu(i-1))/pi
        print*,coslondlon(i),sinlondlon(i)
     enddo
     coslon(1)=coslon(iip1)
     coslondlon(1)=coslondlon(iip1)
     sinlon(1)=sinlon(iip1)
     sinlondlon(1)=sinlondlon(iip1)
     print*,'sum sinlondlon ',ssum(iim,sinlondlon,1)/sinlondlon(1)
     print*,'sum coslondlon ',ssum(iim,coslondlon,1)/coslondlon(1)
    DO l = 1,llm
    DO j = 1,jjp1
     DO i = 1,iip1
     q ( i,j,l,1 )=0.
     q ( i,j,l,2 )=0.
     q ( i,j,l,3 )=0.
     ENDDO
     ENDDO
    ENDDO

  endif
  !   Fin modif Fred

  ! *** q contient les qqtes de traceur avant l'advection

  ! *** Affectation des tableaux S a partir de Q
  ! *** Rem : utilisation de SCOPY ulterieurement

   DO l = 1,llm
    DO j = 1,jjp1
     DO i = 1,iip1
         s0( i,j,llm+1-l ) = q ( i,j,l,0 )
         sx( i,j,llm+1-l ) = q ( i,j,l,1 )
         sy( i,j,llm+1-l ) = q ( i,j,l,2 )
         sz( i,j,llm+1-l ) = q ( i,j,l,3 )
     ENDDO
    ENDDO
   ENDDO

   ! PRINT*,'----- S0 just before conversion -------'
   ! PRINT*,'S0(16,12,1)=',s0(16,12,1)
   ! PRINT*,'Q(16,12,1,4)=',q(16,12,1,4)

  ! *** On calcule la masse d'air en kg

   DO  l = 1,llm
     DO  j = 1,jjp1
       DO  i = 1,iip1
        sm ( i,j,llm+1-l)=masse( i,j,l )
      ENDDO
     ENDDO
   ENDDO

  ! *** On converti les champs S en atome (resp. kg)
  ! *** Les routines d'advection traitent les champs
  ! *** a advecter si ces derniers sont en atome (resp. kg)
  ! *** A optimiser !!!

   DO  l = 1,llm
     DO  j = 1,jjp1
       DO  i = 1,iip1
           s0(i,j,l) = s0(i,j,l) * sm ( i,j,l )
           sx(i,j,l) = sx(i,j,l) * sm ( i,j,l )
           sy(i,j,l) = sy(i,j,l) * sm ( i,j,l )
           sz(i,j,l) = sz(i,j,l) * sm ( i,j,l )
       ENDDO
     ENDDO
   ENDDO

    ! ss0 = 0.
    ! DO l = 1,llm
    !  DO j = 1,jjp1
    !   DO i = 1,iim
    !      ss0 = ss0 + s0 ( i,j,l )
    !   ENDDO
    !  ENDDO
    ! ENDDO
    ! PRINT*, 'valeur tot s0 avant advection=',ss0

  ! *** Appel des subroutines d'advection en X, en Y et en Z
  ! *** Advection avec "time-splitting"

  !-----------------------------------------------------------
   ! PRINT*,'----- S0 just before ADVX -------'
   ! PRINT*,'S0(16,12,1)=',s0(16,12,1)

  !-----------------------------------------------------------
   ! do l=1,llm
   !    do j=1,jjp1
   !     do i=1,iip1
   !        zq=s0(i,j,l)/sm(i,j,l)
   !       if(zq.lt.qmin)
  !    ,       print*,'avant advx1, s0(',i,',',j,',',l,')=',zq
   !     enddo
   !    enddo
   ! enddo
  !CC
   if(mode.eq.2) then
      do l=1,llm
        s0s=0.
        s0n=0.
        dyn1=0.
        dys1=0.
        dyn2=0.
        dys2=0.
        smn=0.
        sms=0.
        do i=1,iim
           smn=smn+sm(i,1,l)
           sms=sms+sm(i,jjp1,l)
           s0n=s0n+s0(i,1,l)
           s0s=s0s+s0(i,jjp1,l)
           zz=sy(i,1,l)/sm(i,1,l)
           dyn1=dyn1+sinlondlon(i)*zz
           dyn2=dyn2+coslondlon(i)*zz
           zz=sy(i,jjp1,l)/sm(i,jjp1,l)
           dys1=dys1+sinlondlon(i)*zz
           dys2=dys2+coslondlon(i)*zz
        enddo
        do i=1,iim
           sy(i,1,l)=dyn1*sinlon(i)+dyn2*coslon(i)
           sy(i,jjp1,l)=dys1*sinlon(i)+dys2*coslon(i)
        enddo
        do i=1,iim
           s0(i,1,l)=s0n/smn+sy(i,1,l)
           s0(i,jjp1,l)=s0s/sms-sy(i,jjp1,l)
        enddo

        s0(iip1,1,l)=s0(1,1,l)
        s0(iip1,jjp1,l)=s0(1,jjp1,l)

        do i=1,iim
           sxn(i)=s0(i+1,1,l)-s0(i,1,l)
           sxs(i)=s0(i+1,jjp1,l)-s0(i,jjp1,l)
  !   on rerentre les masses
        enddo
        do i=1,iim
           sy(i,1,l)=sy(i,1,l)*sm(i,1,l)
           sy(i,jjp1,l)=sy(i,jjp1,l)*sm(i,jjp1,l)
           s0(i,1,l)=s0(i,1,l)*sm(i,1,l)
           s0(i,jjp1,l)=s0(i,jjp1,l)*sm(i,jjp1,l)
        enddo
        sxn(iip1)=sxn(1)
        sxs(iip1)=sxs(1)
        do i=1,iim
           sx(i+1,1,l)=0.25*(sxn(i)+sxn(i+1))*sm(i+1,1,l)
           sx(i+1,jjp1,l)=0.25*(sxs(i)+sxs(i+1))*sm(i+1,jjp1,l)
        enddo
        s0(iip1,1,l)=s0(1,1,l)
        s0(iip1,jjp1,l)=s0(1,jjp1,l)
        sy(iip1,1,l)=sy(1,1,l)
        sy(iip1,jjp1,l)=sy(1,jjp1,l)
        sx(1,1,l)=sx(iip1,1,l)
        sx(1,jjp1,l)=sx(iip1,jjp1,l)
      enddo
  endif

  if (mode.eq.4) then
     do l=1,llm
        do i=1,iip1
           sx(i,1,l)=0.
           sx(i,jjp1,l)=0.
           sy(i,1,l)=0.
           sy(i,jjp1,l)=0.
        enddo
     enddo
  endif
  call limx(s0,sx,sm,pente_max)
  ! call minmaxq(zq,1.e33,-1.e33,'avant advx     ')
   call advx( limit,.5*dtvr,pbaru,sm,s0,sx,sy,sz,lati,latf)
  ! call minmaxq(zq,1.e33,-1.e33,'avant advy     ')
  if (mode.eq.4) then
     do l=1,llm
        do i=1,iip1
           sx(i,1,l)=0.
           sx(i,jjp1,l)=0.
           sy(i,1,l)=0.
           sy(i,jjp1,l)=0.
        enddo
     enddo
  endif
   call   limy(s0,sy,sm,pente_max)
   call advy( limit,.5*dtvr,pbarv,sm,s0,sx,sy,sz )
  ! call minmaxq(zq,1.e33,-1.e33,'avant advz     ')
   do j=1,jjp1
      do i=1,iip1
         sz(i,j,1)=0.
         sz(i,j,llm)=0.
      enddo
   enddo
   call limz(s0,sz,sm,pente_max)
   call advz( limit,dtvr,w,sm,s0,sx,sy,sz )
  if (mode.eq.4) then
     do l=1,llm
        do i=1,iip1
           sx(i,1,l)=0.
           sx(i,jjp1,l)=0.
           sy(i,1,l)=0.
           sy(i,jjp1,l)=0.
        enddo
     enddo
  endif
    call limy(s0,sy,sm,pente_max)
   call advy( limit,.5*dtvr,pbarv,sm,s0,sx,sy,sz )
   do l=1,llm
      do j=1,jjp1
         sm(iip1,j,l)=sm(1,j,l)
         s0(iip1,j,l)=s0(1,j,l)
         sx(iip1,j,l)=sx(1,j,l)
         sy(iip1,j,l)=sy(1,j,l)
         sz(iip1,j,l)=sz(1,j,l)
      enddo
   enddo


  ! call minmaxq(zq,1.e33,-1.e33,'avant advx     ')
  if (mode.eq.4) then
     do l=1,llm
        do i=1,iip1
           sx(i,1,l)=0.
           sx(i,jjp1,l)=0.
           sy(i,1,l)=0.
           sy(i,jjp1,l)=0.
        enddo
     enddo
  endif
   call limx(s0,sx,sm,pente_max)
   call advx( limit,.5*dtvr,pbaru,sm,s0,sx,sy,sz,lati,latf)
  ! call minmaxq(zq,1.e33,-1.e33,'apres advx     ')
  !  do l=1,llm
  !     do j=1,jjp1
  !      do i=1,iip1
  !         zq=s0(i,j,l)/sm(i,j,l)
  !        if(zq.lt.qmin)
  !    ,       print*,'apres advx2, s0(',i,',',j,',',l,')=',zq
  !      enddo
  !     enddo
  !  enddo
  ! ***   On repasse les S dans la variable q directement 14/10/94
  !   On revient a des rapports de melange en divisant par la masse

  ! En dehors des poles:

   DO  l = 1,llm
    DO  j = 1,jjp1
     DO  i = 1,iim
         q(i,j,llm+1-l,0)=s0(i,j,l)/sm(i,j,l)
         q(i,j,llm+1-l,1)=sx(i,j,l)/sm(i,j,l)
         q(i,j,llm+1-l,2)=sy(i,j,l)/sm(i,j,l)
         q(i,j,llm+1-l,3)=sz(i,j,l)/sm(i,j,l)
     ENDDO
    ENDDO
  ENDDO

  ! Traitements specifiques au pole

  if(mode.ge.1) then
  DO l=1,llm
  !   filtrages aux poles
     masn=ssum(iim,sm(1,1,l),1)
     mass=ssum(iim,sm(1,jjp1,l),1)
     qpn=ssum(iim,s0(1,1,l),1)/masn
     qps=ssum(iim,s0(1,jjp1,l),1)/mass
     dqzpn=ssum(iim,sz(1,1,l),1)/masn
     dqzps=ssum(iim,sz(1,jjp1,l),1)/mass
     do i=1,iip1
        q( i,1,llm+1-l,3)=dqzpn
        q( i,jjp1,llm+1-l,3)=dqzps
        q( i,1,llm+1-l,0)=qpn
        q( i,jjp1,llm+1-l,0)=qps
     enddo
     if(mode.eq.3) then
        dyn1=0.
        dys1=0.
        dyn2=0.
        dys2=0.
        do i=1,iim
           dyn1=dyn1+sinlondlon(i)*sy(i,1,l)/sm(i,1,l)
           dyn2=dyn2+coslondlon(i)*sy(i,1,l)/sm(i,1,l)
           dys1=dys1+sinlondlon(i)*sy(i,jjp1,l)/sm(i,jjp1,l)
           dys2=dys2+coslondlon(i)*sy(i,jjp1,l)/sm(i,jjp1,l)
        enddo
        do i=1,iim
           q(i,1,llm+1-l,2)= &
                 (sinlon(i)*dyn1+coslon(i)*dyn2)
           q(i,1,llm+1-l,0)=q(i,1,llm+1-l,0)+q(i,1,llm+1-l,2)
           q(i,jjp1,llm+1-l,2)= &
                 (sinlon(i)*dys1+coslon(i)*dys2)
           q(i,jjp1,llm+1-l,0)=q(i,jjp1,llm+1-l,0) &
                 -q(i,jjp1,llm+1-l,2)
        enddo
     endif
     if(mode.eq.1) then
  !   on filtre les valeurs au bord de la "grande maille pole"
        dyn1=0.
        dys1=0.
        dyn2=0.
        dys2=0.
        do i=1,iim
           zz=s0(i,2,l)/sm(i,2,l)-q(i,1,llm+1-l,0)
           dyn1=dyn1+sinlondlon(i)*zz
           dyn2=dyn2+coslondlon(i)*zz
           zz=q(i,jjp1,llm+1-l,0)-s0(i,jjm,l)/sm(i,jjm,l)
           dys1=dys1+sinlondlon(i)*zz
           dys2=dys2+coslondlon(i)*zz
        enddo
        do i=1,iim
           q(i,1,llm+1-l,2)= &
                 (sinlon(i)*dyn1+coslon(i)*dyn2)/2.
           q(i,1,llm+1-l,0)=q(i,1,llm+1-l,0)+q(i,1,llm+1-l,2)
           q(i,jjp1,llm+1-l,2)= &
                 (sinlon(i)*dys1+coslon(i)*dys2)/2.
           q(i,jjp1,llm+1-l,0)=q(i,jjp1,llm+1-l,0) &
                 -q(i,jjp1,llm+1-l,2)
        enddo
        q(iip1,1,llm+1-l,0)=q(1,1,llm+1-l,0)
        q(iip1,jjp1,llm+1-l,0)=q(1,jjp1,llm+1-l,0)

        do i=1,iim
           sxn(i)=q(i+1,1,llm+1-l,0)-q(i,1,llm+1-l,0)
           sxs(i)=q(i+1,jjp1,llm+1-l,0)-q(i,jjp1,llm+1-l,0)
        enddo
        sxn(iip1)=sxn(1)
        sxs(iip1)=sxs(1)
        do i=1,iim
           q(i+1,1,llm+1-l,1)=0.25*(sxn(i)+sxn(i+1))
           q(i+1,jjp1,llm+1-l,1)=0.25*(sxs(i)+sxs(i+1))
        enddo
        q(1,1,llm+1-l,1)=q(iip1,1,llm+1-l,1)
        q(1,jjp1,llm+1-l,1)=q(iip1,jjp1,llm+1-l,1)

     endif

   ENDDO
   endif

  ! bouclage en longitude
  do iq=0,3
     do l=1,llm
        do j=1,jjp1
           q(iip1,j,l,iq)=q(1,j,l,iq)
        enddo
     enddo
  enddo

    ! PRINT*, ' SORTIE DE PENTES ---  ca peut glisser ....'

    DO l = 1,llm
         DO j = 1,jjp1
          DO i = 1,iip1
            IF (q(i,j,l,0).lt.0.)  THEN
                 ! PRINT*,'------------ BIP-----------'
                 ! PRINT*,'Q0(',i,j,l,')=',q(i,j,l,0)
                 ! PRINT*,'QX(',i,j,l,')=',q(i,j,l,1)
                 ! PRINT*,'QY(',i,j,l,')=',q(i,j,l,2)
                 ! PRINT*,'QZ(',i,j,l,')=',q(i,j,l,3)
                 !         PRINT*,' PBL EN SORTIE DE PENTES'
                 q(i,j,l,0)=0.
                 ! STOP
             ENDIF
      ENDDO
     ENDDO
    ENDDO

    ! PRINT*, '-------------------------------------------'

   do l=1,llm
      do j=1,jjp1
       do i=1,iip1
         if(q(i,j,l,0).lt.qmin) &
               print*,'apres pentes, s0(',i,',',j,',',l,')=',q(i,j,l,0)
       enddo
      enddo
   enddo
  RETURN
END SUBROUTINE pentes_ini