UKCA & UMUI Tutorial 8

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Adding Wet Deposition

The formulationn used in UKCA is described in Giannakopoulos (1999)[1]. This scheme uses the following formula to calculate the effective Henry's Law coefficient

$H_{eff}=k\left(298\right)\exp \left(-{\frac {\Delta H}{R}}\left[\left({\frac {1}{T}}\right)-\left({\frac {1}{298}}\right)\right]\right)$

where $k\left(298\right)$ is the rate constant at 298K.

References

1. Giannakopoulos, C., M. P. Chipperfield, K. S. Law, and J. A. Pyle (1999), Validation and intercomparison of wet and dry deposition schemes using 210Pb in a global three-dimensional off-line chemical transport model, J. Geophys. Res., 104(D19), 23761–23784, doi:10.1029/1999JD900392.

Henry's Law Specification Definition

In the ukca_chem_scheme.F90 the parameters required to calculate $H_{eff}$ are held in the henry_defs_scheme array, and has format

$k(298)$

$-{\Delta H}/R$

$k(298)$ for the 1st dissociatation

$-{\Delta H}/R$ for the 1st dissociatation

$k(298)$ for the 2nd dissociatation

$-{\Delta H}/R$ for the 2nd dissociatation

! The following formula is used to calculate the effective Henry's Law coef,
! which takes the affects of dissociation and complex formation on a species'
! solubility (see Giannakopoulos, 1998)
!
!       H(eff) = K(298)exp{[-deltaH/R]x[(1/T)-(1/298)]}
!
! The data in columns 1 and 2 above give the data for this gas-aqueous transfer,
!       Column 1 = K(298) [M/atm]
!       Column 2 = -deltaH/R [K-1]
!
! If the species dissociates in the aqueous phase the above term is multiplied by
! another factor of 1+{K(aq)/[H+]}, where
!       K(aq) = K(298)exp{[-deltaH/R]x[(1/T)-(1/298)]}
! The data in columns 3 and 4 give the data for this aqueous-phase dissociation,
!       Column 3 = K(298) [M]
!       Column 4 = -deltaH/R [K-1]
! The data in columns 5 and 6 give the data for a second dissociation,
! e.g for SO2, HSO3^{-}, and SO3^{2-}
!       Column 5 = K(298) [M]
!       Column 6 = -deltaH/R [K-1]

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Written by Luke Abraham 2013