methox.F90

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SUBROUTINE methox(KIDIA,  KFDIA,  KLON,  KLEV,PQ,     PTENQ,  PAP )

!**** *METHOX*   - Calculate humidity tendencies from methane
!                  oxidation and photolysis

!**   INTERFACE.
!     ----------
!        CALL *METHOX* FROM *CALLPAR*
!              ------        -------

!        EXPLICIT ARGUMENTS :
!        --------------------
!     PARAMETER     DESCRIPTION                                   UNITS
!     ---------     -----------                                   -----
!     INPUT PARAMETERS (INTEGER):

!    *KIDIA*        START POINT
!    *KFDIA*        END POINT
!    *KLON*         NUMBER OF GRID POINTS PER PACKET
!    *KLEV*         NUMBER OF LEVELS

!     INPUT PARAMETERS (REAL):

!    *PAP*          PRESSURE                                      PA
!    *PQ*           SPECIFIC HUMIDITY                             KG/KG

!     UPDATED PARAMETERS (REAL):

!    *PTENQ*        TENDENCY OF SPECIFIC HUMIDITY                 KG/(KG*S)

!        NONE

!        IMPLICIT ARGUMENTS :
!        --------------------
!        MODULE YOEMETH
!        MODULE YOMCST

!     METHOD.
!     -------
!        SEE RD-MEMO R60.1/AJS/31

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

!     REFERENCE.
!     ----------
!        SEE RD-MEMO R60.1/AJS/31

!     AUTHOR.
!     -------
!        C.JAKOB   *ECMWF*

!     MODIFICATIONS.
!     --------------
!        ORIGINAL : 98-04-07
!        M.Hamrud      01-Oct-2003 CY28 Cleaning
!        D. Cugnet     24-Feb-2012 Adapted for LMDZ
!     ------------------------------------------------------------------

USE yoemeth   , ONLY : ralpha1 ,ralpha2  ,rqlim   ,&
 & rpbotox,  rpbotph ,rptopox  ,rptopph ,&
 & ralpha3,  rlogpph  

IMPLICIT NONE

#include "YOMCST.h"

INTEGER,INTENT(IN)    :: KLON 
INTEGER,INTENT(IN)    :: KLEV 
INTEGER,INTENT(IN)    :: KIDIA 
INTEGER,INTENT(IN)    :: KFDIA 
REAL   ,INTENT(IN)    :: PQ(klon,klev) 
REAL   ,INTENT(INOUT) :: PTENQ(klon,klev) 
REAL   ,INTENT(IN)    :: PAP(klon,klev) 
LOGICAL :: LLOXID,         LLPHOTO

INTEGER :: JK, JL

REAL :: ZARG, ZPRATIO, ZTAU1, ZTAU2, ZTDAYS

DO jk=1,klev
  DO jl=kidia,kfdia

    lloxid=pap(jl,jk) < rpbotox.AND.pq(jl,jk) < rqlim
    llphoto=pap(jl,jk) < rpbotph

!     METHANE OXIDATION

    IF(lloxid) THEN
      IF(pap(jl,jk) <= rptopox) THEN
        ztdays=100.
      ELSE
        zpratio=(log(pap(jl,jk)/rptopox))**4./log(rpbotox/pap(jl,jk))
        ztdays=100.*(1+ralpha1*zpratio)
      ENDIF
      ztau1=86400.*ztdays
      ptenq(jl,jk)=ptenq(jl,jk)+(rqlim-pq(jl,jk))/ztau1
    ENDIF

!     PHOTOLYSIS

    IF(llphoto) THEN
      IF(pap(jl,jk) <= rptopph) THEN
        ztdays=3.
      ELSE
        zarg=ralpha2-ralpha3*(1+cos((rpi*log(pap(jl,jk)/rpbotph))/rlogpph))
        ztdays=1.0/(exp(zarg)-0.01)
      ENDIF
      ztau2=86400.*ztdays
      ptenq(jl,jk)=ptenq(jl,jk)-pq(jl,jk)/ztau2
    ENDIF
  ENDDO
ENDDO

END SUBROUTINE methox