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  • !MNH_LIC Copyright 1994-2014 CNRS, Meteo-France and Universite Paul Sabatier
    
    !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
    
    !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
    
    !MNH_LIC for details. version 1.
    
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    !-----------------------------------------------------------------
    !--------------- special set of characters for RCS information
    !-----------------------------------------------------------------
    ! $Source$ $Revision$
    ! MASDEV4_7 chimie 2006/07/12 18:36:21
    !-----------------------------------------------------------------
    !     ############################
          MODULE MODI_CH_CONVECT_LINOX
    !     ############################
    !
    INTERFACE
    !
          SUBROUTINE CH_CONVECT_LINOX( KLON, KLEV, PCH1, PCH1C,            &
                                       KDPL, KPBL, KLCL, KCTL, KLFS, KDBL, &
                                       PUMF, PUER, PUDR, PDMF, PDER, PDDR, &
                                       PTIMEC, PDXDY, PMIXF, PLMASS, PWSUB,&
                                       KFTSTEPS, PUTT, PRHODREF,           &
                                       OUSECHEM, PZZ, PIC_RATE, PCG_RATE   )
    !
    INTEGER,                INTENT(IN) :: KLON     ! horizontal dimension
    INTEGER,                INTENT(IN) :: KLEV     ! vertical dimension
    !
    REAL,DIMENSION(KLON,KLEV),INTENT(IN)   :: PCH1 ! grid scale tracer concentr.
    REAL,DIMENSION(KLON,KLEV),INTENT(OUT)  :: PCH1C! conv adjusted tracer concntr.
    !
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KDPL   ! index for departure level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KPBL   ! index for top of source layer
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KLCL   ! index lifting condens. level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KCTL   ! index for cloud top level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KLFS   ! index for level of free sink
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KDBL   ! index for downdraft base level
    !
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUMF ! updraft mass flux (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUER ! updraft entrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUDR ! updraft detrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDMF ! downdraft mass flux (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDER ! downdraft entrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDDR ! downdraft detrainment (kg/s)
    !
    REAL, DIMENSION(KLON),     INTENT(IN) :: PTIMEC! convection time step
    REAL, DIMENSION(KLON),     INTENT(IN) :: PDXDY ! grid area (m^2)
    REAL, DIMENSION(KLON),     INTENT(IN) :: PMIXF ! mixed fraction at LFS
    REAL, DIMENSION(KLON,KLEV),INTENT(IN) :: PLMASS! mass of model layer (kg)
    REAL, DIMENSION(KLON,KLEV),INTENT(IN) :: PWSUB ! envir. compensating subsidence(Pa/s)
    INTEGER,                INTENT(IN) :: KFTSTEPS  ! maximum fractional time steps
    REAL, DIMENSION(KLON,KLEV),   INTENT(IN) :: PUTT      ! updraft temperature (K)
    REAL, DIMENSION(KLON,KLEV),   INTENT(IN) :: PRHODREF  
    !
    LOGICAL,                      INTENT(IN) :: OUSECHEM ! to indicate if chemistry is used
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PZZ      ! height of model layer (m)
    REAL, DIMENSION(KLON),     INTENT(INOUT) :: PIC_RATE ! IC lightning frequency
    REAL, DIMENSION(KLON),     INTENT(INOUT) :: PCG_RATE ! CG lightning frequency
    !
    END SUBROUTINE CH_CONVECT_LINOX
    !
    END INTERFACE
    !
    END MODULE MODI_CH_CONVECT_LINOX
    !
    !    ###################################################################
          SUBROUTINE CH_CONVECT_LINOX( KLON, KLEV, PCH1, PCH1C,            &
                                       KDPL, KPBL, KLCL, KCTL, KLFS, KDBL, &
                                       PUMF, PUER, PUDR, PDMF, PDER, PDDR, &
                                       PTIMEC, PDXDY, PMIXF, PLMASS, PWSUB,&
                                       KFTSTEPS, PUTT, PRHODREF,           &
                                       OUSECHEM, PZZ, PIC_RATE, PCG_RATE   )
    !     ##################################################################
    !
    !!**** Compute the production of NOx by lightning flashes inside deep convective
    !!     clouds and its transport
    !!
    !!
    !!    PURPOSE
    !!    -------
    !!      The purpose of this routine is to determine the final adjusted
    !!      environmental values of NOx=NO+NO2 produced by lightning flashes.
    !!      The final convective tendencies can then be evaluated in the main
    !!      routine DEEP_CONVECT by (PCH1C-PCH1)/PTIMEC
    !!
    !!
    !!**  METHOD
    !!    ------
    !!      Identical to the computation of the conservative variables in the
    !!      main deep convection code
    !!
    !!    EXTERNAL
    !!    --------
    !!
    !!    IMPLICIT ARGUMENTS
    !!    ------------------
    !!      Module MODD_CST
    !!          XG                 ! gravity constant
    !!
    !!     Module MODD_CONVPAREXT
    !!          JCVEXB, JCVEXT     ! extra levels on the vertical boundaries
    !!
    !!    AUTHOR
    !!    ------
    !!      T. Fehr       * Laboratoire d'Aerologie *
    !!      J.-P. Pinty   * Laboratoire d'Aerologie *
    !!
    !!    MODIFICATIONS
    !!    -------------
    !!      Original    10/07/03
    !! 
    !-------------------------------------------------------------------------------
    !
    !*       0.    DECLARATIONS
    !              ------------
    !
    USE MODD_CST
    USE MODD_PARAMETERS
    USE MODD_CONVPAREXT
    USE MODD_NSV,     ONLY : NSV_CHEMBEG, NSV_CHEMEND
    !
    !
    USE MODE_ll
    !
    IMPLICIT NONE
    !
    !*       0.1   Declarations of dummy arguments :
    !
    INTEGER,                INTENT(IN) :: KLON     ! horizontal dimension
    INTEGER,                INTENT(IN) :: KLEV     ! vertical dimension
    !
    REAL,DIMENSION(KLON,KLEV),INTENT(IN)   :: PCH1 ! grid scale tracer concentr.
    REAL,DIMENSION(KLON,KLEV),INTENT(OUT)  :: PCH1C! conv adjusted tracer concntr.
    !
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KDPL   ! index for departure level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KPBL   ! index for top of source layer
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KLCL   ! index lifting condens. level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KCTL   ! index for cloud top level
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KLFS   ! index for level of free sink
    INTEGER, DIMENSION(KLON), INTENT(IN) :: KDBL   ! index for downdraft base level
    !
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUMF ! updraft mass flux (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUER ! updraft entrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PUDR ! updraft detrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDMF ! downdraft mass flux (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDER ! downdraft entrainment (kg/s)
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PDDR ! downdraft detrainment (kg/s)
    !
    REAL, DIMENSION(KLON),     INTENT(IN) :: PTIMEC! convection time step
    REAL, DIMENSION(KLON),     INTENT(IN) :: PDXDY ! grid area (m^2)
    REAL, DIMENSION(KLON),     INTENT(IN) :: PMIXF ! mixed fraction at LFS
    REAL, DIMENSION(KLON,KLEV),INTENT(IN) :: PLMASS! mass of model layer (kg)
    REAL, DIMENSION(KLON,KLEV),INTENT(IN) :: PWSUB ! envir. compensating subsidence(Pa/s)
    INTEGER,                INTENT(IN) :: KFTSTEPS  ! maximum fractional time steps
    REAL, DIMENSION(KLON,KLEV),   INTENT(IN) :: PUTT      ! updraft temperature (K)
    REAL, DIMENSION(KLON,KLEV),   INTENT(IN) :: PRHODREF  
    !
    LOGICAL,                      INTENT(IN) :: OUSECHEM ! to indicate if chemistry is used
    REAL, DIMENSION(KLON,KLEV), INTENT(IN) :: PZZ      ! height of model layer (m)
    REAL, DIMENSION(KLON),     INTENT(INOUT) :: PIC_RATE ! IC lightning frequency
    REAL, DIMENSION(KLON),     INTENT(INOUT) :: PCG_RATE ! CG lightning frequency
    !
    !*       0.2   Declarations of local variables :
    !
    INTEGER :: IIB,IIE,IJB,IJE,IKB,IKE  
    INTEGER :: IKS            ! vertical dimension
    INTEGER :: JI,JJ          ! horizontal loop index
    INTEGER :: JK, JKP, JKM   ! vertical loop index
    INTEGER :: JSTEP          ! fractional time loop index
    INTEGER :: JKLC, JKLD, JKLT, JKLB, JKLF, JKLFF, JKLP, JKMAX ! loop index 
                                                                ! of levels
    INTEGER, DIMENSION(KLON) :: ICFL  ! index freezing level
    INTEGER, DIMENSION(KLON) :: ICFFL ! index of -10 degree C level
    !
    REAL, DIMENSION(KLON,KLEV)     :: ZOMG ! compensat. subsidence (Pa/s)
    REAL, DIMENSION(KLON,KLEV,2)     :: ZUCH1, ZDCH1 ! updraft/downdraft values
    REAL, DIMENSION(KLON,KLEV,2)     :: ZCH1C
    REAL, DIMENSION(KLON)          :: ZTIMEC  ! fractional convective time step
    REAL, DIMENSION(KLON,KLEV)     :: ZTIMC! 2D work array for ZTIMEC
    REAL, DIMENSION(KLON,KLEV)     :: ZCH1MFIN, ZCH1MFOUT
                                       ! work arrays for environm. compensat. mass
    REAL, DIMENSION(KLON)          :: ZWORK1, ZWORK2, ZWORK3
    !
    REAL, DIMENSION(KLON)          :: ZCLOUD_DEPTH,       &!
                                      ZTFLASH_RATE,       &!
                                      ZCLOUD_ABOVE_FREEZ, &!
                                      ZBETA,              &!
                                      ZSUM_LMASS_IC,      &!
                                      ZSUM_LMASS_CG
    REAL, DIMENSION(KLON,KLEV)     :: ZNOX_PROD_IC, ZNOX_PROD_CG, ZCH1 
    REAL                           :: XFRAC_UIC, XFRAC_UCG
    !
    ! -----------------------------------------------------------------------------
    !
    !*       0.1   Compute loop bounds
    !              -------------------
    !
    CALL GET_INDICE_ll (IIB,IJB,IIE,IJE)
    IKB    = 1 + JCVEXB 
    IKS    = KLEV
    IKE    = KLEV - JCVEXT 
    JKMAX  = MAXVAL( KCTL(:) )
    !
    !*      1.      Lightning characteristics
    !               -------------------------
    !
    XFRAC_UIC = 1.0 ! Fractional part of IC in updrafts
    XFRAC_UCG = 1.0 ! Fractional part of CG in updrafts
    !
    !*      1.1     Cloud depth
    !               -----------
    !
    DO JI = 1, KLON
      JKLT = KCTL(JI) ! cloud top
      ZCLOUD_DEPTH(JI) = PZZ(JI,JKLT) - PZZ(JI,IKB)
    END DO
    !
    ! Lightning frequency for continental clouds: Price and Rind (1992)
    !
    ZTFLASH_RATE(:) = 0.97241*EXP( (2.76183/XRADIUS**2)*PDXDY(:) ) & ! scale factor
                           * 3.44E-5 * (ZCLOUD_DEPTH(:)*1.0E-3)**4.9
    ZTFLASH_RATE(:) = ZTFLASH_RATE(:)/60. 
    !
    !*      1.2     IC/CG lightning ratio
    !               ---------------------
    !
    ICFL(:) = KLCL(:)
    DO JI = 1, KLON
      DO JK = MINVAL( KLCL(:) ), JKMAX
        IF( PUTT(JI,JK)<XTT ) CYCLE       ! T < 273 K  (bottom level for ICs)
        ICFL(JI) = JK 
      END DO
    END DO
    !
    ICFFL(:) = KCTL(:)
    DO JI = 1, KLON
      DO JK = JKMAX,  MINVAL( KLCL(:) ), -1
        IF( PUTT(JI,JK)>XTT-10.0 ) CYCLE  ! T > 263 K (top level for CGs)
        ICFFL(JI) = JK 
      END DO
    END DO
    !
    DO JI = 1, KLON
      JKLT = KCTL(JI) ! cloud top
      JKLF = ICFL(JI) ! cloud freezing level
      ZCLOUD_ABOVE_FREEZ(JI) = (PZZ(JI,JKLT) - PZZ(JI,JKLF))*1.E-3 ! in km
    END DO
    !
    ZBETA(:) = (((0.021*ZCLOUD_ABOVE_FREEZ(:) -  0.648) &
                       *ZCLOUD_ABOVE_FREEZ(:) +  7.493) &
                       *ZCLOUD_ABOVE_FREEZ(:) - 36.540) &
                       *ZCLOUD_ABOVE_FREEZ(:) + 63.090
    ZBETA(:) = MIN( 48.7, MAX( 0.19,ZBETA(:) ) ) ! 5.5km < ZCLOUD_ABOVE_FREEZ < 14km
    !
    !*      1.3     Profiles of NOx production rates
    !               --------------------------------
    !
    ZNOX_PROD_IC(:,:) = 0.0
    ZNOX_PROD_CG(:,:) = 0.0
    ZSUM_LMASS_IC(:) = 0.0
    ZSUM_LMASS_CG(:) = 0.0
    ZCH1(:,:) = PCH1(:,:) ! initialize with the original value
    DO JI = 1, KLON
      JKLT = KCTL(JI) ! cloud top
      JKLF  = ICFL(JI)  ! cloud freezing level
      JKLFF = ICFFL(JI) ! cloud -10 C level
      IF( JKLT<=JKLF ) THEN
        PIC_RATE(JI) = 0.0
        PCG_RATE(JI) = 0.0
        CYCLE
      ENDIF
    !
    ! IC_NOx production rate
    !
      PIC_RATE(JI) = (ZBETA(JI) / (1.0+ZBETA(JI)))*ZTFLASH_RATE(JI)
      DO JK = JKLF, JKLT
        ZSUM_LMASS_IC(JI)   = ZSUM_LMASS_IC(JI) + PLMASS(JI,JK)
        ZNOX_PROD_IC(JI,JK) = PIC_RATE(JI) * 6.7E25 * PLMASS(JI,JK)
      END DO
      ZNOX_PROD_IC(JI,:) = ZNOX_PROD_IC(JI,:) / ZSUM_LMASS_IC(JI)
    !
    ! CG_NOx production rate
    !
      PCG_RATE(JI) = (1.0 / (1.0+ZBETA(JI)))*ZTFLASH_RATE(JI)
      DO JK = IKB, JKLFF
        ZSUM_LMASS_CG(JI)   = ZSUM_LMASS_CG(JI) + PLMASS(JI,JK)
        ZNOX_PROD_CG(JI,JK) = PCG_RATE(JI) * 6.7E26 * PLMASS(JI,JK)
      END DO
      ZNOX_PROD_CG(JI,:) = ZNOX_PROD_CG(JI,:) / ZSUM_LMASS_CG(JI)
    END DO
    !
    !*      1.4     Update units (molecules/s => pp/s) and integrate
    !               ------------------------------------------------
    !
    ZNOX_PROD_IC(:,IKB:IKE) = ZNOX_PROD_IC(:,IKB:IKE) &
                      *XMD/(XAVOGADRO*PLMASS(:,IKB:IKE))
    ZNOX_PROD_CG(:,IKB:IKE) = ZNOX_PROD_CG(:,IKB:IKE) &
                      *XMD/(XAVOGADRO*PLMASS(:,IKB:IKE))
    !
    !*      2.      Updraft computations
    !               --------------------
    !
    ZUCH1(:,:,:) = 0.
    !
    !*      2.1     Initialization  at LCL
    !               ----------------------
    !
    DO JI = 1, KLON
      JKLD = KDPL(JI)
      JKLP = KPBL(JI)
      ZWORK1(JI) = .5 * ( PCH1(JI,JKLD) + PCH1(JI,JKLP) )
    END DO
    !
    !*      2.2     Final updraft loop
    !               ------------------
    !
    DO JK = MINVAL( KDPL(:) ), JKMAX
      JKP = MIN(JK + 1,JKMAX)
      DO JI = 1, KLON
        IF ( KDPL(JI) <= JK     .AND. KLCL(JI) > JK ) THEN
          ZUCH1(JI,JK,1)  = ZWORK1(JI) 
          ZUCH1(JI,JK,2)  = ZWORK1(JI) + PTIMEC(JI)*(XFRAC_UIC*ZNOX_PROD_IC(JI,JK)&
                                                    +XFRAC_UCG*ZNOX_PROD_CG(JI,JK))
        END IF
        IF ( KLCL(JI) - 1 <= JK .AND. KCTL(JI) > JK ) THEN
          ZUCH1(JI,JKP,1) = ( PUMF(JI,JK)  * ZUCH1(JI,JK,1) +                     &
                              PUER(JI,JKP) * PCH1(JI,JK)                          &
                            )  / ( PUMF(JI,JKP) + PUDR(JI,JKP) )
          IF ( KLFS(JI) -1 >= JK ) THEN
            ZUCH1(JI,JKP,2) = ( PUMF(JI,JK)  * ZUCH1(JI,JK,2) +                   &
                                PUER(JI,JKP) * PCH1(JI,JK)  +                     &
                            PLMASS(JI,JKP) * (XFRAC_UIC*ZNOX_PROD_IC(JI,JKP)      &
                                             +XFRAC_UCG*ZNOX_PROD_CG(JI,JKP))     &
                            )  / ( PUMF(JI,JKP) + PUDR(JI,JKP) )
          ELSE                                                                    
            ZUCH1(JI,JKP,2) = ( PUMF(JI,JK)  * ZUCH1(JI,JK,2) +                   &
                                PUER(JI,JKP) * PCH1(JI,JK)  +                     &
                            PLMASS(JI,JKP) * (ZNOX_PROD_IC(JI,JKP)                &
                                             +ZNOX_PROD_CG(JI,JKP))               &
                            )  / ( PUMF(JI,JKP) + PUDR(JI,JKP) )
    
          END IF
        END IF
      END DO
    END DO
    !
    !*      3.      Downdraft computations
    !               ----------------------
    !
    ZDCH1(:,:,:) = 0.
    !
    !*      3.1     Initialization at the LFS and at the DBL
    !               ----------------------------------------
    !
    DO JI = 1, KLON
      JK = KLFS(JI)
      ZDCH1(JI,JK,1) = PMIXF(JI)*PCH1(JI,JK) + ( 1. - PMIXF(JI) )*ZUCH1(JI,JK,1)
      ZDCH1(JI,JK,2) = PMIXF(JI)*PCH1(JI,JK) + ( 1. - PMIXF(JI) )*ZUCH1(JI,JK,2)  &
                       + PTIMEC(JI) * ((1-XFRAC_UIC)*ZNOX_PROD_IC(JI,JK) +        &
                                       (1-XFRAC_UCG)*ZNOX_PROD_CG(JI,JK))
    END DO
    !
    !*      3.2     Final downdraft loop
    !               --------------------
    !
    DO JK = MAXVAL( KLFS(:) ), IKB + 1, -1
      JKM = JK - 1
      DO JI = 1, KLON
        IF ( JK <= KLFS(JI) .AND. JKM >= KDBL(JI) ) THEN
          ZDCH1(JI,JKM,1) = ( PDMF(JI,JK)  * ZDCH1(JI,JK,1) -                     &
                              PDER(JI,JKM) * PCH1(JI,JK)                          &
                            )  / ( PDMF(JI,JKM) - PDDR(JI,JKM) ) 
          ZDCH1(JI,JKM,2) = ( PDMF(JI,JK) *ZDCH1(JI,JK,2) -                       &
                              PDER(JI,JKM)*PCH1(JI,JK)  -                         &
                            PLMASS(JI,JKM)*((1.0-XFRAC_UIC)*ZNOX_PROD_IC(JI,JKM)  &
                                            +(1.0-XFRAC_UCG)*ZNOX_PROD_CG(JI,JKM))&
                            )  / ( PDMF(JI,JKM) - PDDR(JI,JKM) ) 
        END IF
      END DO
    END DO
    !							   
    !*      4.      Final closure (environmental) computations
    !               ------------------------------------------
    !
    ZCH1C(:,:,1) = ZCH1(:,:) ! initialize adjusted envir. values followed by an 
    ZCH1C(:,:,2) = ZCH1(:,:) ! initialize adjusted envir. values followed by an 
    !
    DO JK = IKB, IKE
      ZOMG(:,JK) = PWSUB(:,JK) * PDXDY(:) / XG ! environmental subsidence
    END DO
    !
    ZTIMEC(:) = PTIMEC(:) / REAL( KFTSTEPS ) ! adjust  fractional time step
                                             ! to be an integer multiple of PTIMEC
    WHERE ( PTIMEC(:) < 1. ) ZTIMEC(:) = 0.
    ZTIMC(:,:)= SPREAD( ZTIMEC(:), DIM=2, NCOPIES=IKS )
    !
    DO jj=1,2
      ZCH1MFIN(:,:)   = 0.
      ZCH1MFOUT(:,:)  = 0.
    !
      DO JSTEP = 1, KFTSTEPS ! Enter the fractional time step loop
        DO JK = IKB + 1, JKMAX
          JKP = MAX( IKB + 1, JK - 1 )
          ZWORK3(:) = ZOMG(:,JK)
          ZWORK1(:) = SIGN( 1., ZWORK3(:) )
          ZWORK2(:) = 0.5 * ( 1. + ZWORK1(:) )
          ZWORK1(:) = 0.5 * ( 1. - ZWORK1(:) )
          ZCH1MFIN(:,JK)  = - ZWORK3(:) * ZCH1C(:,JKP,jj) * ZWORK1(:)
          ZCH1MFOUT(:,JK) =   ZWORK3(:) * ZCH1C(:,JK,jj)  * ZWORK2(:)
          ZCH1MFIN(:,JKP) = ZCH1MFIN(:,JKP) + ZCH1MFOUT(:,JK) * ZWORK2(:)
          ZCH1MFOUT(:,JKP)= ZCH1MFOUT(:,JKP) + ZCH1MFIN(:,JK) * ZWORK1(:)
        END DO
    !
        DO JK = IKB + 1, JKMAX
          ZCH1C(:,JK,jj) = ZCH1C(:,JK,jj) + ZTIMC(:,JK) / PLMASS(:,JK) *  (    &
                       ZCH1MFIN(:,JK) + PUDR(:,JK) * ZUCH1(:,JK,jj) +       &
                       PDDR(:,JK) * ZDCH1(:,JK,jj) - ZCH1MFOUT(:,JK) -      &
                        ( PUER(:,JK) + PDER(:,JK) ) * PCH1(:,JK)    )
          ZCH1C(:,JK,jj) = MAX( 0., ZCH1C(:,JK,jj) )
        END DO
      END DO ! Exit the fractional time step loop
    END DO
    !
    !
    !----------------------------------------------------------------------------
    !
    !*           8.8    Apply conservation correction
    !                   -----------------------------
    !
    ZCH1MFIN(:,:)= ZCH1C(:,:,2)- ZCH1C(:,:,1)
    !
    !
    ! Compute vertical integrals
    !
    ZWORK1(:) = 0.
    ZWORK2(:) = 0.
    DO JI = 1, KLON
      JKP = KCTL(JI)
      IF(JKP < IKB+1)CYCLE
      DO JK = IKB+1, JKP
        ZWORK1(JI) = ZWORK1(JI) + (ZCH1C(JI,JK,1)-PCH1(JI,JK)) *        &
                                  .5 * (PLMASS(JI,JK-1) + PLMASS(JI,JK+1))
        ZWORK2(JI) = ZWORK2(JI) +                                       &
                              .5 * (PLMASS(JI,JK-1) + PLMASS(JI,JK+1))
      END DO
      ZWORK1(JI) = ZWORK1(JI) / ZWORK2(JI)
    END DO
    !
    ! Mass error (integral must be zero)
    !
    ! Apply uniform correction but assure positive mass at each level
    !
    DO JI = 1, KLON
      JKP = KCTL(JI)
      IF(JKP < IKB+1)CYCLE
      DO JK = IKB+1, JKP
        ZCH1C(JI,JK,1) = ZCH1C(JI,JK,1) - ZWORK1(JI)
      END DO
    END DO
    !
    ! Compute vertical integrals
    !
    ZWORK1(:) = 0.
    DO JI = 1, KLON
      JKP = KCTL(JI)
      IF(JKP < IKB+1)CYCLE
      DO JK = IKB+1, JKP
        ZWORK1(JI) = ZWORK1(JI) + (ZCH1C(JI,JK,1)-PCH1(JI,JK)) *        &
                                .5 * (PLMASS(JI,JK-1) + PLMASS(JI,JK+1))
      END DO
    END DO
    !
    ! Mass error (integral must be zero)
    !
    !
    ! Add final
    !
    PCH1C(:,:) = ZCH1C(:,:,1) + ZCH1MFIN(:,:)
    PCH1C(:,:) = MAX(0.,PCH1C(:,:))
    !
    !----------------------------------------------------------------------------
    !
    !
    END SUBROUTINE CH_CONVECT_LINOX