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GEOS-Chem-adjoint-v35-note/code/fyhoro.f
2018-08-28 00:43:47 -04:00

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! $Id: fyhoro.f,v 1.1 2009/06/09 21:51:53 daven Exp $
!------------------------------------------------------------------------------
! Harvard University Atmospheric Chemistry Modeling Group !
!------------------------------------------------------------------------------
!BOP
!
! !FUNCTION: FYHORO
!
! !DESCRIPTION: \subsection*{Overview}
! Function FYHORO returns returns the branching ratio between
! HOC2H4O oxidation and dissociation:
! (1) HOC2H4 --O2--> HO2 + GLYC
! (2) HOC2H4 ------> HO2 + 2CH2O
!\subsection*{References}
! \begin{enumerate}
! \item Orlando et al., 1998: \emph{Laboratory and theoretical study of the
! oxyradicals in the OH- and Cl-initiated oxidation of ethene},
! \underline{J. Phys. Chem. A}, \textbf{102}, 8116-8123.
! \item Orlando et al., 2003: \emph{The atmospheric chemistry of alkoxy
! radicals}, \underline{Chem. Rev.}, \textbf{103}, 4657-4689.
! \end{enumerate}
!
!\\
!\\
! !INTERFACE:
!
REAL*8 FUNCTION FYHORO( ZDNUM, TT )
!
! !USES:
!
IMPLICIT NONE
!
! !INPUT PARAMETERS:
!
! Air density [molec/cm3 ]
REAL*8, INTENT(IN) :: ZDNUM
! Temperature [K ]
REAL*8, INTENT(IN) :: TT
!
! !REVISION HISTORY:
! (1 ) Branching ratio calculation (tmf, 2/6/05).
!EOP
!------------------------------------------------------------------------------
!BOC
!
! !LOCAL VARIABLES:
!
REAL*8 :: K1, K2, O2DNUM
!=================================================================
! FYHORO begins here!
!=================================================================
O2DNUM = ZDNUM * 0.21D0
K1 = 6.0D-14 * EXP(-550.D0/TT) * O2DNUM
K2 = 9.5D+13 * EXP(-5988.D0/TT)
FYHORO = K1 / (K1 + K2)
! Return to calling program
END FUNCTION FYHORO
!EOC