SUBROUTINE PPPMER(KPROMA, KSTART, KPROF, PRPRESS, POROG, PTSTAR, PT0, PMSLPPP)

  !**** *PPPMER* - POST-PROCESS MSL PRESSURE.

  !     PURPOSE.
  !     --------
  !           COMPUTES MSL PRESSURE.

  !**   INTERFACE.
  !     ----------

  !        *CALL* *PPPMER(KPROMA,KSTART,KPROF,PRPRESS,POROG,PTSTAR,PT0,
  !    S                  PMSLPPP)

  !        EXPLICIT ARGUMENTS
  !        --------------------


  !        KPROMA                    - HORIZONTAL DIMENSION.             (INPUT)
  !        KSTART                    - START OF WORK.                    (INPUT)
  !        KPROF                     - DEPTH OF WORK.                    (INPUT)
  !        PRPRESS(KPROMA)           - SURFACE PRESSURE                  (INPUT)
  !        POROG(KPROMA)             - MODEL OROGRAPHY.                  (INPUT)
  !        PTSTAR(KPROMA)            - SURFACE TEMPERATURE               (INPUT)
  !        PT0(KPROMA)               - STANDARD SURFACE TEMPERATURE      (INPUT)
  !        PMSLPPP(KPROMA)           - POST-PROCESSED MSL PRESSURE       (OUTPUT)
  !        IMPLICIT ARGUMENTS :  CONSTANTS FROM YOMCST,YOMGEM,YOMSTA.
  !        --------------------

  !     METHOD.
  !     -------
  !        SEE DOCUMENTATION

  !     EXTERNALS.  NONE
  !     ----------

  !     REFERENCE.
  !     ----------
  !        ECMWF Research Department documentation of the IFS

  !     AUTHOR.
  !     -------
  !        MATS HAMRUD AND PHILIPPE COURTIER  *ECMWF*

  !     MODIFICATIONS.
  !     --------------
  !        ORIGINAL : 89-01-26

  !     E. A-son, J-F Geleyn 920409 Mod. T*, T0 and alpha below surface.
  !        M.Hamrud      01-Oct-2003 CY28 Cleaning

  !     ------------------------------------------------------------------

  ! USE PARKIND1
  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/xrd/module/parkind1.F90.php#parkind1>  ,ONLY: JPIM     ,JPRB
  ! USE YOMHOOK
  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/xrd/module/yomhook.F90.php#yomhook>   ,ONLY: LHOOK,   DR_HOOK

  !USE YOMCST, ONLY: RG, RD
  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/arp/module/yomcst.F90.php#yomcst>   , ONLY: RG

  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/xrd/support/rg.F.php#rg>       ,RD
  ! USE YOMSTA
  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/arp/module/yomsta.F90.php#yomsta>   , ONLY: RDTDZ1

  USE lmdz_yomcst

  IMPLICIT NONE

  !IM INTEGER(KIND=JPIM),INTENT(IN)    :: KPROMA
  !IM INTEGER(KIND=JPIM),INTENT(IN)    :: KSTART
  !IM INTEGER(KIND=JPIM),INTENT(IN)    :: KPROF
  INTEGER, INTENT(IN) :: KPROMA
  INTEGER, INTENT(IN) :: KSTART
  INTEGER, INTENT(IN) :: KPROF
  !IM REAL(KIND=JPRB)   ,INTENT(IN)    :: PRPRESS(KPROMA)
  !IM REAL(KIND=JPRB)   ,INTENT(IN)    :: POROG(KPROMA)
  !IM REAL(KIND=JPRB)   ,INTENT(IN)    :: PTSTAR(KPROMA)
  !IM REAL(KIND=JPRB)   ,INTENT(IN)    :: PT0(KPROMA)
  !IM REAL(KIND=JPRB)   ,INTENT(OUT)   :: PMSLPPP(KPROMA)
  !IM REAL(KIND=JPRB) :: ZTSTAR(KPROMA)
  !IM REAL(KIND=JPRB) :: ZALPHA(KPROMA)
  REAL, INTENT(IN) :: PRPRESS(KPROMA)
  REAL, INTENT(IN) :: POROG(KPROMA)
  REAL, INTENT(IN) :: PTSTAR(KPROMA)
  REAL, INTENT(IN) :: PT0(KPROMA)
  REAL, INTENT(OUT) :: PMSLPPP(KPROMA)
  REAL :: ZTSTAR(KPROMA)
  REAL :: ZALPHA(KPROMA)

  !IM INTEGER(KIND=JPIM) :: JL
  INTEGER :: JL

  !IM REAL(KIND=JPRB) :: ZDTDZSG, ZOROG, ZT0, ZTX, ZTY, ZX, ZY, ZY2
  !IM REAL(KIND=JPRB) :: ZHOOK_HANDLE
  REAL :: ZDTDZSG, ZOROG, ZT0, ZTX, ZTY, ZX, ZY, ZY2
  REAL :: ZHOOK_HANDLE
  !IM beg
  REAL, PARAMETER :: RDTDZ1 = -0.0065 !or USE YOMSTA
  !IM end

  !     ------------------------------------------------------------------

  !*       1.    POST-PROCESS MSL PRESSURE.
  !              --------------------------

  !*       1.1   COMPUTATION OF MODIFIED ALPHA AND TSTAR.

  !IM IF (LHOOK) CALL DR_HOOK('PPPMER',0,ZHOOK_HANDLE)
  !IM ZTX=290.5_JPRB
  !IM ZTY=255.0_JPRB
  ZTX = 290.5
  ZTY = 255.0
  ZDTDZSG = -RDTDZ1 / RG
  !<http://intra.cnrm.meteo.fr/eac/ARPCLI5.2/doci/code/arpcli5.2/xrd/support/rg.F.php#rg>
  DO JL = KSTART, KPROF

    IF(PTSTAR(JL) < ZTY) THEN
      !IM  ZTSTAR(JL)=0.5_JPRB*(ZTY+PTSTAR(JL))
      ZTSTAR(JL) = 0.5 * (ZTY + PTSTAR(JL))
    ELSEIF(PTSTAR(JL) < ZTX) THEN
      ZTSTAR(JL) = PTSTAR(JL)
    ELSE
      !IM    ZTSTAR(JL)=0.5_JPRB*(ZTX+PTSTAR(JL))
      ZTSTAR(JL) = 0.5 * (ZTX + PTSTAR(JL))
    ENDIF

    ZT0 = ZTSTAR(JL) + ZDTDZSG * POROG(JL)
    IF(ZTX > ZTSTAR(JL) .AND. ZT0 > ZTX) THEN
      ZT0 = ZTX
    ELSEIF(ZTX <= ZTSTAR(JL) .AND. ZT0 > ZTSTAR(JL)) THEN
      ZT0 = ZTSTAR(JL)
    ELSE
      ZT0 = PT0(JL)
    ENDIF

    !IM  ZOROG=SIGN(MAX(1.0_JPRB,ABS(POROG(JL))),POROG(JL))
    ZOROG = SIGN(MAX(1.0, ABS(POROG(JL))), POROG(JL))
    ZALPHA(JL) = RD * (ZT0 - ZTSTAR(JL)) / ZOROG
  ENDDO

  !*       1.2   COMPUTATION OF MSL PRESSURE.

  DO JL = KSTART, KPROF
    !IM  IF (ABS(POROG(JL)) >= 0.001_JPRB) THEN
    IF (ABS(POROG(JL)) >= 0.001) THEN
      ZX = POROG(JL) / (RD * ZTSTAR(JL))
      ZY = ZALPHA(JL) * ZX
      ZY2 = ZY * ZY

      !IM    PMSLPPP(JL)=PRPRESS(JL)*EXP(ZX*(1.0_JPRB-0.5_JPRB*ZY+1.0_JPRB/3._JPRB*ZY2))
      PMSLPPP(JL) = PRPRESS(JL) * EXP(ZX * (1.0 - 0.5 * ZY + 1.0 / 3. * ZY2))
    ELSE
      PMSLPPP(JL) = PRPRESS(JL)
    ENDIF
  ENDDO


  !     ------------------------------------------------------------------

  !IM IF (LHOOK) CALL DR_HOOK('PPPMER',1,ZHOOK_HANDLE)
END SUBROUTINE PPPMER