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   SUBROUTINE ultimate_y( kloop, pamsk, kn_umx, pdt, pt, pv, pt_v, pfv_ho )
      !!---------------------------------------------------------------------
      !!                    ***  ROUTINE ultimate_y  ***
      !!
      !! **  Purpose :   compute tracer at v-points
      !!
      !! **  Method  :   ...
      !!
      !! Reference : Leonard, B.P., 1991, Comput. Methods Appl. Mech. Eng., 88, 17-74.
      !!----------------------------------------------------------------------
      INTEGER                         , INTENT(in   ) ::   kloop     ! either 0 or nn_hls depending on the order of the call
      REAL(wp)                        , INTENT(in   ) ::   pamsk     ! advection of concentration (1) or other tracers (0)
      INTEGER                         , INTENT(in   ) ::   kn_umx    ! order of the scheme (1-5=UM or 20=CEN2)
      REAL(wp)                        , INTENT(in   ) ::   pdt       ! tracer time-step
      REAL(wp), DIMENSION(:,:  )      , INTENT(in   ) ::   pv        ! ice j-velocity component
      REAL(wp), DIMENSION(:,:,:)      , INTENT(in   ) ::   pt        ! tracer fields
      REAL(wp), DIMENSION(jpi,jpj,jpl), INTENT(  out) ::   pt_v      ! tracer at v-point
      REAL(wp), DIMENSION(jpi,jpj,jpl), INTENT(  out) ::   pfv_ho    ! high order flux
      !
      INTEGER  ::   ji, jj, jl         ! dummy loop indices
      REAL(wp) ::   zcv, zdy2, zdy4    !   -      -
      REAL(wp), DIMENSION(jpi,jpj,jpl) ::   ztv1, ztv2, ztv3, ztv4
      !!----------------------------------------------------------------------
      !
      !                                                     !--  Laplacian in j-direction  --!
      DO jl = 1, jpl
         DO_2D( kloop, kloop, nn_hls, nn_hls-1 )      ! First derivative (gradient)
            ztv1(ji,jj,jl) = ( pt(ji,jj+1,jl) - pt(ji,jj,jl) ) * r1_e2v(ji,jj) * vmask(ji,jj,1)
         END_2D
         DO_2D( kloop, kloop, nn_hls-1, nn_hls-1 )    ! Second derivative (Laplacian)
            ztv2(ji,jj,jl) = ( ztv1(ji,jj,jl) - ztv1(ji,jj-1,jl) ) * r1_e2t(ji,jj)
         END_2D
      END DO
      IF( nn_hls == 1 )   CALL lbc_lnk( 'icedyn_adv_umx', ztv2, 'T', 1.0_wp )
      !
      !                                                     !--  BiLaplacian in j-direction  --!
      DO jl = 1, jpl
         DO_2D( kloop, kloop, 1, 0 )                  ! Third derivative
            ztv3(ji,jj,jl) = ( ztv2(ji,jj+1,jl) - ztv2(ji,jj,jl) ) * r1_e2v(ji,jj) * vmask(ji,jj,1)
         END_2D
         DO_2D( kloop, kloop, 0, 0 )                  ! Fourth derivative
            ztv4(ji,jj,jl) = ( ztv3(ji,jj,jl) - ztv3(ji,jj-1,jl) ) * r1_e2t(ji,jj)
         END_2D
      END DO
      !
      !
      SELECT CASE (kn_umx )
         !
      CASE( 1 )                                                !==  1st order central TIM  ==! (Eq. 21)
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (                                pt(ji,jj+1,jl) + pt(ji,jj,jl)   &
                  &                                         - SIGN( 1._wp, pv(ji,jj) ) * ( pt(ji,jj+1,jl) - pt(ji,jj,jl) ) )
            END_2D
         END DO
         !
      CASE( 2 )                                                !==  2nd order central TIM  ==! (Eq. 23)
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               zcv  = pv(ji,jj) * r1_e1v(ji,jj) * pdt * r1_e2v(ji,jj)
               pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (                                pt(ji,jj+1,jl) + pt(ji,jj,jl)   &
                  &                                                            - zcv *   ( pt(ji,jj+1,jl) - pt(ji,jj,jl) ) )
            END_2D
         END DO
         !
      CASE( 3 )                                                !==  3rd order central TIM  ==! (Eq. 24)
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               zcv  = pv(ji,jj) * r1_e1v(ji,jj) * pdt * r1_e2v(ji,jj)
               zdy2 = e2v(ji,jj) * e2v(ji,jj)
!!rachid          zdy2 = e2v(ji,jj) * e2t(ji,jj)
               pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (      (                         pt  (ji,jj+1,jl) + pt  (ji,jj,jl)     &
                  &                                                            - zcv   * ( pt  (ji,jj+1,jl) - pt  (ji,jj,jl) ) ) &
                  &        + r1_6 * zdy2 * ( zcv*zcv - 1._wp ) * (                         ztv2(ji,jj+1,jl) + ztv2(ji,jj,jl)     &
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                  &                                               - SIGN( 1._wp, zcv ) * ( ztv2(ji,jj+1,jl) - ztv2(ji,jj,jl) ) ) )
            END_2D
         END DO
         !
      CASE( 4 )                                                !==  4th order central TIM  ==! (Eq. 27)
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               zcv  = pv(ji,jj) * r1_e1v(ji,jj) * pdt * r1_e2v(ji,jj)
               zdy2 = e2v(ji,jj) * e2v(ji,jj)
!!rachid          zdy2 = e2v(ji,jj) * e2t(ji,jj)
               pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (      (                         pt  (ji,jj+1,jl) + pt  (ji,jj,jl)     &
                  &                                                            - zcv   * ( pt  (ji,jj+1,jl) - pt  (ji,jj,jl) ) ) &
                  &        + r1_6 * zdy2 * ( zcv*zcv - 1._wp ) * (                         ztv2(ji,jj+1,jl) + ztv2(ji,jj,jl)     &
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                  &                                                   - 0.5_wp * zcv   * ( ztv2(ji,jj+1,jl) - ztv2(ji,jj,jl) ) ) )
            END_2D
         END DO
         !
      CASE( 5 )                                                !==  5th order central TIM  ==! (Eq. 29)
         !
         CALL lbc_lnk( 'icedyn_adv_umx', ztv4, 'T', 1.0_wp )
         !
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               zcv  = pv(ji,jj) * r1_e1v(ji,jj) * pdt * r1_e2v(ji,jj)
               zdy2 = e2v(ji,jj) * e2v(ji,jj)
!!rachid          zdy2 = e2v(ji,jj) * e2t(ji,jj)
               zdy4 = zdy2 * zdy2
               pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (                              ( pt  (ji,jj+1,jl) + pt  (ji,jj,jl)     &
                  &                                                            - zcv   * ( pt  (ji,jj+1,jl) - pt  (ji,jj,jl) ) ) &
                  &        + r1_6   * zdy2 * ( zcv*zcv - 1._wp ) * (                       ztv2(ji,jj+1,jl) + ztv2(ji,jj,jl)     &
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                  &                                                   - 0.5_wp * zcv   * ( ztv2(ji,jj+1,jl) - ztv2(ji,jj,jl) ) ) &
                  &        + r1_120 * zdy4 * ( zcv*zcv - 1._wp ) * ( zcv*zcv - 4._wp ) * ( ztv4(ji,jj+1,jl) + ztv4(ji,jj,jl)     &
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                  &                                               - SIGN( 1._wp, zcv ) * ( ztv4(ji,jj+1,jl) - ztv4(ji,jj,jl) ) ) )
            END_2D
         END DO
         !
      END SELECT
      !
      ! if pt at v-point is negative then use the upstream value
      !    this should not be necessary if a proper sea-ice mask is set in Ultimate
      !    to degrade the order of the scheme when necessary (for ex. at the ice edge)
      IF( ll_neg ) THEN
         DO jl = 1, jpl
            DO_2D( kloop, kloop, 1, 0 )
               IF( pt_v(ji,jj,jl) < 0._wp .OR. ( jmsk_small(ji,jj,jl) == 0 .AND. pamsk == 0. ) ) THEN
                  pt_v(ji,jj,jl) = 0.5_wp * vmask(ji,jj,1) * (                              ( pt(ji,jj+1,jl) + pt(ji,jj,jl) )  &
                     &                                         - SIGN( 1._wp, pv(ji,jj) ) * ( pt(ji,jj+1,jl) - pt(ji,jj,jl) ) )
               ENDIF
            END_2D
         END DO
      ENDIF
      !                                                     !-- High order flux in j-direction  --!
      DO jl = 1, jpl
         DO_2D( 0, 0, 1, 0 )
            pfv_ho(ji,jj,jl) = pv(ji,jj) * pt_v(ji,jj,jl)
         END_2D
      END DO
      !
   END SUBROUTINE ultimate_y


   SUBROUTINE nonosc_ice( pamsk, pdt, pu, pv, pt, pt_ups, pfu_ups, pfv_ups, pfu_ho, pfv_ho )
      !!---------------------------------------------------------------------
      !!                    ***  ROUTINE nonosc_ice  ***
      !!
      !! **  Purpose :   compute monotonic tracer fluxes from the upstream
      !!       scheme and the before field by a non-oscillatory algorithm
      !!
      !! **  Method  :   ...
      !!----------------------------------------------------------------------
      REAL(wp)                   , INTENT(in   ) ::   pamsk            ! advection of concentration (1) or other tracers (0)
      REAL(wp)                   , INTENT(in   ) ::   pdt              ! tracer time-step
      REAL(wp), DIMENSION (:,:  ), INTENT(in   ) ::   pu               ! ice i-velocity => u*e2
      REAL(wp), DIMENSION (:,:  ), INTENT(in   ) ::   pv               ! ice j-velocity => v*e1
      REAL(wp), DIMENSION (:,:,:), INTENT(in   ) ::   pt, pt_ups       ! before field & upstream guess of after field
      REAL(wp), DIMENSION (:,:,:), INTENT(in   ) ::   pfv_ups, pfu_ups ! upstream flux
      REAL(wp), DIMENSION (:,:,:), INTENT(inout) ::   pfv_ho, pfu_ho   ! monotonic flux
      !
      INTEGER  ::   ji, jj, jl    ! dummy loop indices
      REAL(wp) ::   zpos, zneg, zbig, zup, zdo, z1_dt              ! local scalars
      REAL(wp) ::   zau, zbu, zcu, zav, zbv, zcv, zcoef, zzt       !   -      -
      REAL(wp), DIMENSION(jpi,jpj    ) :: zbup, zbdo
      REAL(wp), DIMENSION(jpi,jpj,jpl) :: zbetup, zbetdo, zti_ups, ztj_ups
      !!----------------------------------------------------------------------
      zbig = 1.e+40_wp

      ! antidiffusive flux : high order minus low order
      ! --------------------------------------------------
      DO jl = 1, jpl
         DO_2D( 1, 0, 0, 0 )
            pfu_ho(ji,jj,jl) = pfu_ho(ji,jj,jl) - pfu_ups(ji,jj,jl)
         END_2D
         DO_2D( 0, 0, 1, 0 )
            pfv_ho(ji,jj,jl) = pfv_ho(ji,jj,jl) - pfv_ups(ji,jj,jl)
         END_2D
      END DO

      ! extreme case where pfu_ho has to be zero
      ! ----------------------------------------
      !                                    pfu_ho
      !                           *         --->
      !                        |      |  *   |        |
      !                        |      |      |    *   |
      !                        |      |      |        |    *
      !            t_ups :       i-1     i       i+1       i+2
      IF( ll_prelim ) THEN

         DO jl = 1, jpl
            DO_2D( 0, 0, 0, 0 )
               zti_ups(ji,jj,jl)= pt_ups(ji+1,jj  ,jl)
               ztj_ups(ji,jj,jl)= pt_ups(ji  ,jj+1,jl)
            END_2D
         END DO
         CALL lbc_lnk( 'icedyn_adv_umx', zti_ups, 'T', 1.0_wp, ztj_ups, 'T', 1.0_wp )

         DO jl = 1, jpl
            DO_2D( 0, 0, 0, 0 )
               IF ( pfu_ho(ji,jj,jl) * ( pt_ups(ji+1,jj  ,jl) - pt_ups(ji,jj,jl) ) <= 0._wp .AND.  &
                  & pfv_ho(ji,jj,jl) * ( pt_ups(ji  ,jj+1,jl) - pt_ups(ji,jj,jl) ) <= 0._wp ) THEN
                  !
                  IF(  pfu_ho(ji,jj,jl) * ( zti_ups(ji+1,jj  ,jl) - zti_ups(ji,jj,jl) ) <= 0._wp .AND.  &
                     & pfv_ho(ji,jj,jl) * ( ztj_ups(ji  ,jj+1,jl) - ztj_ups(ji,jj,jl) ) <= 0._wp ) THEN
                     pfu_ho(ji,jj,jl)=0._wp
                     pfv_ho(ji,jj,jl)=0._wp
                  ENDIF
                  !
                  IF(  pfu_ho(ji,jj,jl) * ( pt_ups(ji,jj,jl) - pt_ups(ji-1,jj  ,jl) ) <= 0._wp .AND.  &
                     & pfv_ho(ji,jj,jl) * ( pt_ups(ji,jj,jl) - pt_ups(ji  ,jj-1,jl) ) <= 0._wp ) THEN
                     pfu_ho(ji,jj,jl)=0._wp
                     pfv_ho(ji,jj,jl)=0._wp
                  ENDIF
                  !
               ENDIF
            END_2D
         END DO
         CALL lbc_lnk( 'icedyn_adv_umx', pfu_ho, 'U', -1.0_wp, pfv_ho, 'V', -1.0_wp )   ! lateral boundary cond.

      ENDIF

      ! Search local extrema
      ! --------------------
      ! max/min of pt & pt_ups with large negative/positive value (-/+zbig) outside ice cover
      z1_dt = 1._wp / pdt
      DO jl = 1, jpl

         DO_2D( 1, 1, 1, 1 )
            IF    ( pt(ji,jj,jl) <= 0._wp .AND. pt_ups(ji,jj,jl) <= 0._wp ) THEN
               zbup(ji,jj) = -zbig
               zbdo(ji,jj) =  zbig
            ELSEIF( pt(ji,jj,jl) <= 0._wp .AND. pt_ups(ji,jj,jl) > 0._wp ) THEN
               zbup(ji,jj) = pt_ups(ji,jj,jl)
               zbdo(ji,jj) = pt_ups(ji,jj,jl)
            ELSEIF( pt(ji,jj,jl) > 0._wp .AND. pt_ups(ji,jj,jl) <= 0._wp ) THEN
               zbup(ji,jj) = pt(ji,jj,jl)
               zbdo(ji,jj) = pt(ji,jj,jl)
            ELSE
               zbup(ji,jj) = MAX( pt(ji,jj,jl) , pt_ups(ji,jj,jl) )
               zbdo(ji,jj) = MIN( pt(ji,jj,jl) , pt_ups(ji,jj,jl) )
            ENDIF
         END_2D

         DO_2D( 0, 0, 0, 0 )
            !
            zup  = MAX( zbup(ji,jj), zbup(ji-1,jj), zbup(ji+1,jj), zbup(ji,jj-1), zbup(ji,jj+1) )  ! search max/min in neighbourhood
            zdo  = MIN( zbdo(ji,jj), zbdo(ji-1,jj), zbdo(ji+1,jj), zbdo(ji,jj-1), zbdo(ji,jj+1) )
            !
            zpos = MAX( 0._wp, pfu_ho(ji-1,jj  ,jl) ) - MIN( 0._wp, pfu_ho(ji  ,jj  ,jl) ) &  ! positive/negative part of the flux
               & + MAX( 0._wp, pfv_ho(ji  ,jj-1,jl) ) - MIN( 0._wp, pfv_ho(ji  ,jj  ,jl) )
            zneg = MAX( 0._wp, pfu_ho(ji  ,jj  ,jl) ) - MIN( 0._wp, pfu_ho(ji-1,jj  ,jl) ) &
               & + MAX( 0._wp, pfv_ho(ji  ,jj  ,jl) ) - MIN( 0._wp, pfv_ho(ji  ,jj-1,jl) )
            !
            zpos = zpos - (pt(ji,jj,jl) * MIN( 0., pu(ji,jj) - pu(ji-1,jj) ) + pt(ji,jj,jl) * MIN( 0., pv(ji,jj) - pv(ji,jj-1) ) &
               &          ) * ( 1. - pamsk )
            zneg = zneg + (pt(ji,jj,jl) * MAX( 0., pu(ji,jj) - pu(ji-1,jj) ) + pt(ji,jj,jl) * MAX( 0., pv(ji,jj) - pv(ji,jj-1) ) &
               &          ) * ( 1. - pamsk )
            !
            !                                  ! up & down beta terms
            ! clem: zbetup and zbetdo must be 0 for zpos>1.e-10 & zneg>1.e-10 (do not put 0 instead of 1.e-10 !!!)
            IF( zpos > epsi10 ) THEN ; zbetup(ji,jj,jl) = MAX( 0._wp, zup - pt_ups(ji,jj,jl) ) / zpos * e1e2t(ji,jj) * z1_dt
            ELSE                     ; zbetup(ji,jj,jl) = 0._wp ! zbig
            ENDIF
            !
            IF( zneg > epsi10 ) THEN ; zbetdo(ji,jj,jl) = MAX( 0._wp, pt_ups(ji,jj,jl) - zdo ) / zneg * e1e2t(ji,jj) * z1_dt
            ELSE                     ; zbetdo(ji,jj,jl) = 0._wp ! zbig
            ENDIF
            !
            ! if all the points are outside ice cover
            IF( zup == -zbig )   zbetup(ji,jj,jl) = 0._wp ! zbig
            IF( zdo ==  zbig )   zbetdo(ji,jj,jl) = 0._wp ! zbig
            !
         END_2D
      END DO
      CALL lbc_lnk( 'icedyn_adv_umx', zbetup, 'T', 1.0_wp, zbetdo, 'T', 1.0_wp )   ! lateral boundary cond. (unchanged sign)


      ! monotonic flux in the y direction
      ! ---------------------------------
      DO jl = 1, jpl
         DO_2D( 1, 0, 0, 0 )
            zau = MIN( 1._wp , zbetdo(ji,jj,jl) , zbetup(ji+1,jj,jl) )
            zbu = MIN( 1._wp , zbetup(ji,jj,jl) , zbetdo(ji+1,jj,jl) )
            zcu = 0.5_wp + SIGN( 0.5_wp , pfu_ho(ji,jj,jl) )
            !
            zcoef = ( zcu * zau + ( 1._wp - zcu ) * zbu )
            !
            pfu_ho(ji,jj,jl) = pfu_ho(ji,jj,jl) * zcoef + pfu_ups(ji,jj,jl)
            !
         END_2D

         DO_2D( 0, 0, 1, 0 )
            zav = MIN( 1._wp , zbetdo(ji,jj,jl) , zbetup(ji,jj+1,jl) )
            zbv = MIN( 1._wp , zbetup(ji,jj,jl) , zbetdo(ji,jj+1,jl) )
            zcv = 0.5_wp + SIGN( 0.5_wp , pfv_ho(ji,jj,jl) )
            !
            zcoef = ( zcv * zav + ( 1._wp - zcv ) * zbv )
            !
            pfv_ho(ji,jj,jl) = pfv_ho(ji,jj,jl) * zcoef + pfv_ups(ji,jj,jl)
            !
         END_2D

      END DO
      !
   END SUBROUTINE nonosc_ice


   SUBROUTINE limiter_x( pdt, pu, pt, pfu_ups, pfu_ho )
      !!---------------------------------------------------------------------
      !!                    ***  ROUTINE limiter_x  ***
      !!
      !! **  Purpose :   compute flux limiter
      !!----------------------------------------------------------------------
      REAL(wp)                  , INTENT(in   ) ::   pdt          ! tracer time-step
      REAL(wp), DIMENSION(:,:  ), INTENT(in   ) ::   pu           ! ice i-velocity => u*e2
      REAL(wp), DIMENSION(:,:,:), INTENT(in   ) ::   pt           ! ice tracer
      REAL(wp), DIMENSION(:,:,:), INTENT(in   ) ::   pfu_ups      ! upstream flux
      REAL(wp), DIMENSION(:,:,:), INTENT(inout) ::   pfu_ho       ! high order flux
      !
      REAL(wp) ::   Cr, Rjm, Rj, Rjp, uCFL, zpsi, zh3, zlimiter, Rr
      INTEGER  ::   ji, jj, jl    ! dummy loop indices
      REAL(wp), DIMENSION (jpi,jpj,jpl) ::   zslpx       ! tracer slopes
      !!----------------------------------------------------------------------
      !
      DO jl = 1, jpl
         DO_2D( nn_hls, nn_hls-1, 0, 0 )
            zslpx(ji,jj,jl) = ( pt(ji+1,jj,jl) - pt(ji,jj,jl) ) * umask(ji,jj,1)
         END_2D
      END DO
      IF( nn_hls == 1 )   CALL lbc_lnk( 'icedyn_adv_umx', zslpx, 'U', -1.0_wp)   ! lateral boundary cond.

      DO jl = 1, jpl
         DO_2D( nn_hls-1, 0, 0, 0 )
            uCFL = pdt * ABS( pu(ji,jj) ) * r1_e1e2t(ji,jj)

            Rjm = zslpx(ji-1,jj,jl)
            Rj  = zslpx(ji  ,jj,jl)
            Rjp = zslpx(ji+1,jj,jl)

            IF( np_limiter == 3 ) THEN

               IF( pu(ji,jj) > 0. ) THEN   ;   Rr = Rjm
               ELSE                        ;   Rr = Rjp
               ENDIF

               zh3 = pfu_ho(ji,jj,jl) - pfu_ups(ji,jj,jl)
               IF( Rj > 0. ) THEN
                  zlimiter =  MAX( 0., MIN( zh3, MAX(-Rr * 0.5 * ABS(pu(ji,jj)),  &
                     &        MIN( 2. * Rr * 0.5 * ABS(pu(ji,jj)),  zh3,  1.5 * Rj * 0.5 * ABS(pu(ji,jj)) ) ) ) )
               ELSE
                  zlimiter = -MAX( 0., MIN(-zh3, MAX( Rr * 0.5 * ABS(pu(ji,jj)),  &
                     &        MIN(-2. * Rr * 0.5 * ABS(pu(ji,jj)), -zh3, -1.5 * Rj * 0.5 * ABS(pu(ji,jj)) ) ) ) )
               ENDIF
               pfu_ho(ji,jj,jl) = pfu_ups(ji,jj,jl) + zlimiter

            ELSEIF( np_limiter == 2 ) THEN
               IF( Rj /= 0. ) THEN
                  IF( pu(ji,jj) > 0. ) THEN   ;   Cr = Rjm / Rj
                  ELSE                        ;   Cr = Rjp / Rj
                  ENDIF
               ELSE
                  Cr = 0.
               ENDIF

               ! -- superbee --
               zpsi = MAX( 0., MAX( MIN(1.,2.*Cr), MIN(2.,Cr) ) )
               ! -- van albada 2 --
               !!zpsi = 2.*Cr / (Cr*Cr+1.)
               ! -- sweby (with beta=1) --
               !!zpsi = MAX( 0., MAX( MIN(1.,1.*Cr), MIN(1.,Cr) ) )
               ! -- van Leer --
               !!zpsi = ( Cr + ABS(Cr) ) / ( 1. + ABS(Cr) )
               ! -- ospre --
               !!zpsi = 1.5 * ( Cr*Cr + Cr ) / ( Cr*Cr + Cr + 1. )
               ! -- koren --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( (1.+2*Cr)/3., 2. ) ) )
               ! -- charm --
               !IF( Cr > 0. ) THEN   ;   zpsi = Cr * (3.*Cr + 1.) / ( (Cr + 1.) * (Cr + 1.) )
               !ELSE                 ;   zpsi = 0.
               !ENDIF
               ! -- van albada 1 --
               !!zpsi = (Cr*Cr + Cr) / (Cr*Cr +1)
               ! -- smart --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( 0.25+0.75*Cr, 4. ) ) )
               ! -- umist --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( 0.25+0.75*Cr, MIN(0.75+0.25*Cr, 2. ) ) ) )

               ! high order flux corrected by the limiter
               pfu_ho(ji,jj,jl) = pfu_ho(ji,jj,jl) - ABS( pu(ji,jj) ) * ( (1.-zpsi) + uCFL*zpsi ) * Rj * 0.5

            ENDIF
         END_2D
      END DO
      IF( nn_hls == 1 )   CALL lbc_lnk( 'icedyn_adv_umx', pfu_ho, 'U', -1.0_wp)   ! lateral boundary cond.
      !
   END SUBROUTINE limiter_x


   SUBROUTINE limiter_y( pdt, pv, pt, pfv_ups, pfv_ho )
      !!---------------------------------------------------------------------
      !!                    ***  ROUTINE limiter_y  ***
      !!
      !! **  Purpose :   compute flux limiter
      !!----------------------------------------------------------------------
      REAL(wp)                   , INTENT(in   ) ::   pdt          ! tracer time-step
      REAL(wp), DIMENSION (:,:  ), INTENT(in   ) ::   pv           ! ice i-velocity => u*e2
      REAL(wp), DIMENSION (:,:,:), INTENT(in   ) ::   pt           ! ice tracer
      REAL(wp), DIMENSION (:,:,:), INTENT(in   ) ::   pfv_ups      ! upstream flux
      REAL(wp), DIMENSION (:,:,:), INTENT(inout) ::   pfv_ho       ! high order flux
      !
      REAL(wp) ::   Cr, Rjm, Rj, Rjp, vCFL, zpsi, zh3, zlimiter, Rr
      INTEGER  ::   ji, jj, jl    ! dummy loop indices
      REAL(wp), DIMENSION (jpi,jpj,jpl) ::   zslpy       ! tracer slopes
      !!----------------------------------------------------------------------
      !
      DO jl = 1, jpl
         DO_2D( 0, 0, nn_hls, nn_hls-1 )
            zslpy(ji,jj,jl) = ( pt(ji,jj+1,jl) - pt(ji,jj,jl) ) * vmask(ji,jj,1)
         END_2D
      END DO
      IF( nn_hls == 1 )   CALL lbc_lnk( 'icedyn_adv_umx', zslpy, 'V', -1.0_wp)   ! lateral boundary cond.

      DO jl = 1, jpl
         DO_2D( 0, 0, nn_hls-1, 0 )
            vCFL = pdt * ABS( pv(ji,jj) ) * r1_e1e2t(ji,jj)

            Rjm = zslpy(ji,jj-1,jl)
            Rj  = zslpy(ji,jj  ,jl)
            Rjp = zslpy(ji,jj+1,jl)

            IF( np_limiter == 3 ) THEN

               IF( pv(ji,jj) > 0. ) THEN   ;   Rr = Rjm
               ELSE                        ;   Rr = Rjp
               ENDIF

               zh3 = pfv_ho(ji,jj,jl) - pfv_ups(ji,jj,jl)
               IF( Rj > 0. ) THEN
                  zlimiter =  MAX( 0., MIN( zh3, MAX(-Rr * 0.5 * ABS(pv(ji,jj)),  &
                     &        MIN( 2. * Rr * 0.5 * ABS(pv(ji,jj)),  zh3,  1.5 * Rj * 0.5 * ABS(pv(ji,jj)) ) ) ) )
               ELSE
                  zlimiter = -MAX( 0., MIN(-zh3, MAX( Rr * 0.5 * ABS(pv(ji,jj)),  &
                     &        MIN(-2. * Rr * 0.5 * ABS(pv(ji,jj)), -zh3, -1.5 * Rj * 0.5 * ABS(pv(ji,jj)) ) ) ) )
               ENDIF
               pfv_ho(ji,jj,jl) = pfv_ups(ji,jj,jl) + zlimiter

            ELSEIF( np_limiter == 2 ) THEN

               IF( Rj /= 0. ) THEN
                  IF( pv(ji,jj) > 0. ) THEN   ;   Cr = Rjm / Rj
                  ELSE                        ;   Cr = Rjp / Rj
                  ENDIF
               ELSE
                  Cr = 0.
               ENDIF

               ! -- superbee --
               zpsi = MAX( 0., MAX( MIN(1.,2.*Cr), MIN(2.,Cr) ) )
               ! -- van albada 2 --
               !!zpsi = 2.*Cr / (Cr*Cr+1.)
               ! -- sweby (with beta=1) --
               !!zpsi = MAX( 0., MAX( MIN(1.,1.*Cr), MIN(1.,Cr) ) )
               ! -- van Leer --
               !!zpsi = ( Cr + ABS(Cr) ) / ( 1. + ABS(Cr) )
               ! -- ospre --
               !!zpsi = 1.5 * ( Cr*Cr + Cr ) / ( Cr*Cr + Cr + 1. )
               ! -- koren --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( (1.+2*Cr)/3., 2. ) ) )
               ! -- charm --
               !IF( Cr > 0. ) THEN   ;   zpsi = Cr * (3.*Cr + 1.) / ( (Cr + 1.) * (Cr + 1.) )
               !ELSE                 ;   zpsi = 0.
               !ENDIF
               ! -- van albada 1 --
               !!zpsi = (Cr*Cr + Cr) / (Cr*Cr +1)
               ! -- smart --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( 0.25+0.75*Cr, 4. ) ) )
               ! -- umist --
               !!zpsi = MAX( 0., MIN( 2.*Cr, MIN( 0.25+0.75*Cr, MIN(0.75+0.25*Cr, 2. ) ) ) )

               ! high order flux corrected by the limiter
               pfv_ho(ji,jj,jl) = pfv_ho(ji,jj,jl) - ABS( pv(ji,jj) ) * ( (1.-zpsi) + vCFL*zpsi ) * Rj * 0.5

            ENDIF
         END_2D
      END DO
      IF( nn_hls == 1 )   CALL lbc_lnk( 'icedyn_adv_umx', pfv_ho, 'V', -1.0_wp)   ! lateral boundary cond.
      !
   END SUBROUTINE limiter_y


   SUBROUTINE Hbig( pdt, phi_max, phs_max, phip_max, psi_max, pes_max, pei_max, &
      &                  pv_i, pv_s, pa_i, pa_ip, pv_ip, psv_i, pe_s, pe_i )
      !!-------------------------------------------------------------------
      !!                  ***  ROUTINE Hbig  ***
      !!
      !! ** Purpose : Thickness correction in case advection scheme creates
      !!              abnormally tick ice or snow
      !!
      !! ** Method  : 1- check whether ice thickness is larger than the surrounding 9-points
      !!                 (before advection) and reduce it by adapting ice concentration
      !!              2- check whether snow thickness is larger than the surrounding 9-points
      !!                 (before advection) and reduce it by sending the excess in the ocean
      !!
      !! ** input   : Max thickness of the surrounding 9-points
      !!-------------------------------------------------------------------
      REAL(wp)                    , INTENT(in   ) ::   pdt                                   ! tracer time-step
      REAL(wp), DIMENSION(:,:,:)  , INTENT(in   ) ::   phi_max, phs_max, phip_max, psi_max   ! max ice thick from surrounding 9-pts
      REAL(wp), DIMENSION(:,:,:,:), INTENT(in   ) ::   pes_max
      REAL(wp), DIMENSION(:,:,:,:), INTENT(in   ) ::   pei_max
      REAL(wp), DIMENSION(:,:,:)  , INTENT(inout) ::   pv_i, pv_s, pa_i, pa_ip, pv_ip, psv_i
      REAL(wp), DIMENSION(:,:,:,:), INTENT(inout) ::   pe_s
      REAL(wp), DIMENSION(:,:,:,:), INTENT(inout) ::   pe_i
      !
      INTEGER  ::   ji, jj, jk, jl         ! dummy loop indices
      REAL(wp) ::   z1_dt, zhip, zhi, zhs, zsi, zes, zei, zfra
      !!-------------------------------------------------------------------
      !
      z1_dt = 1._wp / pdt
      !
      DO jl = 1, jpl
         DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
            IF ( pv_i(ji,jj,jl) > 0._wp ) THEN
               !
               !                               ! -- check h_ip -- !
               ! if h_ip is larger than the surrounding 9 pts => reduce h_ip and increase a_ip
               IF( ( ln_pnd_LEV .OR. ln_pnd_TOPO ) .AND. pv_ip(ji,jj,jl) > 0._wp ) THEN
                  zhip = pv_ip(ji,jj,jl) / MAX( epsi20, pa_ip(ji,jj,jl) )
                  IF( zhip > phip_max(ji,jj,jl) .AND. pa_ip(ji,jj,jl) < 0.15 ) THEN
                     pa_ip(ji,jj,jl) = pv_ip(ji,jj,jl) / phip_max(ji,jj,jl)
                  ENDIF
               ENDIF
               !
               !                               ! -- check h_i -- !
               ! if h_i is larger than the surrounding 9 pts => reduce h_i and increase a_i
               zhi = pv_i(ji,jj,jl) / pa_i(ji,jj,jl)
               IF( zhi > phi_max(ji,jj,jl) .AND. pa_i(ji,jj,jl) < 0.15 ) THEN
                  pa_i(ji,jj,jl) = pv_i(ji,jj,jl) / MIN( phi_max(ji,jj,jl), hi_max(jpl) )   !-- bound h_i to hi_max (99 m)
               ENDIF
               !
               !                               ! -- check h_s -- !
               ! if h_s is larger than the surrounding 9 pts => put the snow excess in the ocean
               zhs = pv_s(ji,jj,jl) / pa_i(ji,jj,jl)
               IF( pv_s(ji,jj,jl) > 0._wp .AND. zhs > phs_max(ji,jj,jl) .AND. pa_i(ji,jj,jl) < 0.15 ) THEN
                  zfra = phs_max(ji,jj,jl) / MAX( zhs, epsi20 )
                  !
                  wfx_res(ji,jj) = wfx_res(ji,jj) + ( pv_s(ji,jj,jl) - pa_i(ji,jj,jl) * phs_max(ji,jj,jl) ) * rhos * z1_dt
                  hfx_res(ji,jj) = hfx_res(ji,jj) - SUM( pe_s(ji,jj,1:nlay_s,jl) ) * ( 1._wp - zfra ) * z1_dt ! W.m-2 <0
                  !
                  pe_s(ji,jj,1:nlay_s,jl) = pe_s(ji,jj,1:nlay_s,jl) * zfra
                  pv_s(ji,jj,jl)          = pa_i(ji,jj,jl) * phs_max(ji,jj,jl)
               ENDIF
               !
               !                               ! -- check s_i -- !
               ! if s_i is larger than the surrounding 9 pts => put salt excess in the ocean
               zsi = psv_i(ji,jj,jl) / pv_i(ji,jj,jl)
               IF( zsi > psi_max(ji,jj,jl) .AND. pa_i(ji,jj,jl) < 0.15 ) THEN
                  zfra = psi_max(ji,jj,jl) / zsi
                  sfx_res(ji,jj) = sfx_res(ji,jj) + psv_i(ji,jj,jl) * ( 1._wp - zfra ) * rhoi * z1_dt
                  psv_i(ji,jj,jl) = psv_i(ji,jj,jl) * zfra
               ENDIF
               !
            ENDIF
         END_2D
      END DO
      !
      !                                           ! -- check e_i/v_i -- !
      DO jl = 1, jpl
         DO_3D( nn_hls, nn_hls, nn_hls, nn_hls, 1, nlay_i )
            IF ( pv_i(ji,jj,jl) > 0._wp ) THEN
               ! if e_i/v_i is larger than the surrounding 9 pts => put the heat excess in the ocean
               zei = pe_i(ji,jj,jk,jl) / pv_i(ji,jj,jl)
               IF( zei > pei_max(ji,jj,jk,jl) .AND. pa_i(ji,jj,jl) < 0.15 ) THEN
                  zfra = pei_max(ji,jj,jk,jl) / zei
                  hfx_res(ji,jj) = hfx_res(ji,jj) - pe_i(ji,jj,jk,jl) * ( 1._wp - zfra ) * z1_dt ! W.m-2 <0
                  pe_i(ji,jj,jk,jl) = pe_i(ji,jj,jk,jl) * zfra
               ENDIF
            ENDIF
         END_3D
      END DO
      !                                           ! -- check e_s/v_s -- !
      DO jl = 1, jpl
         DO_3D( nn_hls, nn_hls, nn_hls, nn_hls, 1, nlay_s )
            IF ( pv_s(ji,jj,jl) > 0._wp ) THEN
               ! if e_s/v_s is larger than the surrounding 9 pts => put the heat excess in the ocean
               zes = pe_s(ji,jj,jk,jl) / pv_s(ji,jj,jl)
               IF( zes > pes_max(ji,jj,jk,jl) .AND. pa_i(ji,jj,jl) < 0.15 ) THEN
                  zfra = pes_max(ji,jj,jk,jl) / zes
                  hfx_res(ji,jj) = hfx_res(ji,jj) - pe_s(ji,jj,jk,jl) * ( 1._wp - zfra ) * z1_dt ! W.m-2 <0
                  pe_s(ji,jj,jk,jl) = pe_s(ji,jj,jk,jl) * zfra
               ENDIF
            ENDIF
         END_3D
      END DO
      !
   END SUBROUTINE Hbig


   SUBROUTINE Hsnow( pdt, pv_i, pv_s, pa_i, pa_ip, pe_s )
      !!-------------------------------------------------------------------
      !!                  ***  ROUTINE Hsnow  ***
      !!
      !! ** Purpose : 1- Check snow load after advection
      !!              2- Correct pond concentration to avoid a_ip > a_i
      !!
      !! ** Method :  If snow load makes snow-ice interface to deplet below the ocean surface
      !!              then put the snow excess in the ocean
      !!
      !! ** Notes :   This correction is crucial because of the call to routine icecor afterwards
      !!              which imposes a mini of ice thick. (rn_himin). This imposed mini can artificially
      !!              make the snow very thick (if concentration decreases drastically)
      !!              This behavior has been seen in Ultimate-Macho and supposedly it can also be true for Prather
      !!-------------------------------------------------------------------
      REAL(wp)                    , INTENT(in   ) ::   pdt   ! tracer time-step
      REAL(wp), DIMENSION(:,:,:)  , INTENT(inout) ::   pv_i, pv_s, pa_i, pa_ip
      REAL(wp), DIMENSION(:,:,:,:), INTENT(inout) ::   pe_s
      !
      INTEGER  ::   ji, jj, jl   ! dummy loop indices
      REAL(wp) ::   z1_dt, zvs_excess, zfra
      !!-------------------------------------------------------------------
      !
      z1_dt = 1._wp / pdt
      !
      ! -- check snow load -- !
      DO jl = 1, jpl
         DO_2D( nn_hls, nn_hls, nn_hls, nn_hls )
            IF ( pv_i(ji,jj,jl) > 0._wp ) THEN
               !
               zvs_excess = MAX( 0._wp, pv_s(ji,jj,jl) - pv_i(ji,jj,jl) * (rho0-rhoi) * r1_rhos )
               !
               IF( zvs_excess > 0._wp ) THEN   ! snow-ice interface deplets below the ocean surface
                  ! put snow excess in the ocean
                  zfra = ( pv_s(ji,jj,jl) - zvs_excess ) / MAX( pv_s(ji,jj,jl), epsi20 )
                  wfx_res(ji,jj) = wfx_res(ji,jj) + zvs_excess * rhos * z1_dt
                  hfx_res(ji,jj) = hfx_res(ji,jj) - SUM( pe_s(ji,jj,1:nlay_s,jl) ) * ( 1._wp - zfra ) * z1_dt ! W.m-2 <0
                  ! correct snow volume and heat content
                  pe_s(ji,jj,1:nlay_s,jl) = pe_s(ji,jj,1:nlay_s,jl) * zfra
                  pv_s(ji,jj,jl)          = pv_s(ji,jj,jl) - zvs_excess
               ENDIF
               !
            ENDIF
         END_2D
      END DO
      !
      !-- correct pond concentration to avoid a_ip > a_i -- !
      WHERE( pa_ip(:,:,:) > pa_i(:,:,:) )   pa_ip(:,:,:) = pa_i(:,:,:)
      !
   END SUBROUTINE Hsnow

   SUBROUTINE icemax3D( pice , pmax )
      !!---------------------------------------------------------------------
      !!                   ***  ROUTINE icemax3D ***
      !! ** Purpose :  compute the max of the 9 points around
      !!----------------------------------------------------------------------
      REAL(wp), DIMENSION(:,:,:), INTENT(in ) ::   pice   ! input
      REAL(wp), DIMENSION(:,:,:), INTENT(out) ::   pmax   ! output
      !
      REAL(wp), DIMENSION(Nis0:Nie0) ::   zmax1, zmax2
      REAL(wp)                       ::   zmax3
      INTEGER  ::   ji, jj, jl   ! dummy loop indices
      !!----------------------------------------------------------------------
      ! basic version: get the max of epsi20 + 9 neighbours
!!$      DO jl = 1, jpl
!!$         DO_2D( 0, 0, 0, 0 )
!!$            pmax(ji,jj,jl) = MAX( epsi20, pice(ji-1,jj-1,jl), pice(ji,jj-1,jl), pice(ji+1,jj-1,jl),   &
!!$               &                          pice(ji-1,jj  ,jl), pice(ji,jj  ,jl), pice(ji+1,jj  ,jl),   &
!!$               &                          pice(ji-1,jj+1,jl), pice(ji,jj+1,jl), pice(ji+1,jj+1,jl) )
!!$         END_2D
!!$      END DO
      ! optimized version : does a little bit more than 2 max of epsi20 + 3 neighbours
      DO jl = 1, jpl
         DO ji = Nis0, Nie0
            zmax1(ji) = MAX( epsi20, pice(ji,Njs0-1,jl), pice(ji-1,Njs0-1,jl), pice(ji+1,Njs0-1,jl) )
            zmax2(ji) = MAX( epsi20, pice(ji,Njs0  ,jl), pice(ji-1,Njs0  ,jl), pice(ji+1,Njs0  ,jl) )
         END DO
         DO_2D( 0, 0, 0, 0 )
            zmax3 = MAX( epsi20, pice(ji,jj+1,jl), pice(ji-1,jj+1,jl), pice(ji+1,jj+1,jl) )
            pmax(ji,jj,jl) = MAX( epsi20, zmax1(ji), zmax2(ji), zmax3 )
            zmax1(ji) = zmax2(ji)
            zmax2(ji) = zmax3
         END_2D
      END DO
   END SUBROUTINE icemax3D

   SUBROUTINE icemax4D( pice , pmax )
      !!---------------------------------------------------------------------
      !!                   ***  ROUTINE icemax4D ***
      !! ** Purpose :  compute the max of the 9 points around
      !!----------------------------------------------------------------------
      REAL(wp), DIMENSION(:,:,:,:), INTENT(in ) ::   pice   ! input
      REAL(wp), DIMENSION(:,:,:,:), INTENT(out) ::   pmax   ! output
      !
      REAL(wp), DIMENSION(Nis0:Nie0) ::   zmax1, zmax2
      REAL(wp)                       ::   zmax3
      INTEGER  ::   jlay, ji, jj, jk, jl   ! dummy loop indices
      !!----------------------------------------------------------------------
      jlay = SIZE( pice , 3 )   ! size of input arrays
      ! basic version: get the max of epsi20 + 9 neighbours
!!$      DO jl = 1, jpl
!!$         DO jk = 1, jlay
!!$            DO_2D( 0, 0, 0, 0 )
!!$               pmax(ji,jj,jk,jl) = MAX( epsi20, pice(ji-1,jj-1,jk,jl), pice(ji,jj-1,jk,jl), pice(ji+1,jj-1,jk,jl),   &
!!$                  &                             pice(ji-1,jj  ,jk,jl), pice(ji,jj  ,jk,jl), pice(ji+1,jj  ,jk,jl),   &
!!$                  &                             pice(ji-1,jj+1,jk,jl), pice(ji,jj+1,jk,jl), pice(ji+1,jj+1,jk,jl) )
!!$            END_2D
!!$         END DO
!!$      END DO
      ! optimized version : does a little bit more than 2 max of epsi20 + 3 neighbours
      DO jl = 1, jpl
         DO jk = 1, jlay
            DO ji = Nis0, Nie0
               zmax1(ji) = MAX( epsi20, pice(ji,Njs0-1,jk,jl), pice(ji-1,Njs0-1,jk,jl), pice(ji+1,Njs0-1,jk,jl) )
               zmax2(ji) = MAX( epsi20, pice(ji,Njs0  ,jk,jl), pice(ji-1,Njs0  ,jk,jl), pice(ji+1,Njs0  ,jk,jl) )
            END DO
            DO_2D( 0, 0, 0, 0 )
               zmax3 = MAX( epsi20, pice(ji,jj+1,jk,jl), pice(ji-1,jj+1,jk,jl), pice(ji+1,jj+1,jk,jl) )
               pmax(ji,jj,jk,jl) = MAX( epsi20, zmax1(ji), zmax2(ji), zmax3 )
               zmax1(ji) = zmax2(ji)
               zmax2(ji) = zmax3
            END_2D
         END DO
      END DO
   END SUBROUTINE icemax4D

#else
   !!----------------------------------------------------------------------
   !!   Default option           Dummy module         NO SI3 sea-ice model
   !!----------------------------------------------------------------------
#endif

   !!======================================================================
END MODULE icedyn_adv_umx