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code/fyhoro.f

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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