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mod_carbonchem.F90
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mod_carbonchem.F90
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! -*- f90 -*-
MODULE MOD_CARBONCHEM
! Import modules from the SOLVESAPHE package of Munhoven (2013)
!
! Copyright 2013 Guy Munhoven
!
! SolveSAPHE is free software: you can redistribute it and/or modify
! it under the terms of the GNU Lesser General Public License as published by
! the Free Software Foundation, either version 3 of the License, or
! (at your option) any later version.
!
! SolveSAPHE is distributed in the hope that it will be useful,
! but WITHOUT ANY WARRANTY; without even the implied warranty of
! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
! GNU Lesser General Public License for more details.
!
! You should have received a copy of the GNU Lesser General Public License
! along with SolveSAPHE. If not, see <http://www.gnu.org/licenses/>.
!
USE MOD_PRECISION
USE MOD_COMMON, ONLY : one, permil, conv_molkg_molm3, &
conv_cmhr_ms, Kwexch_av
USE MOD_CHEMCONST
USE MOD_PHSOLVERS
USE MOD_CHEMSPECIATION
USE MOD_BOXES
IMPLICIT NONE
! --------------------------------------------------------
! List of (PRIVATE) routines/functions
! --------------------------------------------------------
! PRIVATE AK_FFATM_WEIS80
! PRIVATE AK_FFOCE_WEIS74
! PRIVATE AK_CARB_0_WEIS74
! REAL(KIND=wp), PARAMETER :: gasconst_bar_cm3_o_mol_k = 83.14510_wp ! libthdyct
!REAL(KIND=wp), PARAMETER, PRIVATE :: gasconst_bar_cm3_o_mol_k = 83.14472_wp ! Handbook (2007)
! 0 degrees centigrade in Kelvin
! REAL(KIND=wp), PARAMETER :: t_k_zerodegc = 273.15_wp ! Handbook (2007)
! Pressure at one atmosphere (bar)
REAL(KIND=wp), PARAMETER :: p_bar_oneatmosphere = 1.01325_wp ! Handbook (2007)
! --------------------------------------------------------------
! variable for usage by users of the module
! --------------------------------------------------------------
REAL(KIND=wp) :: apiff_atm, apiff_oce
REAL(KIND=wp) :: api0_dic
CONTAINS
!=======================================================================
SUBROUTINE SETUP_FLUXCOEFFS(t_k, s)
! ------------------
! Argument variables
! ------------------
! t_k : temperature in Kelvin
! s : salinity
REAL(KIND=wp), INTENT(IN) :: t_k
REAL(KIND=wp), INTENT(IN) :: s
apiff_atm = AK_FFATM_WEIS80 (t_k, s)
apiff_oce = AK_FFOCE_WEIS74 (t_k, s)
api0_dic = AK_CARB_0_WEIS74(t_k, s)
RETURN
END SUBROUTINE SETUP_FLUXCOEFFS
!=======================================================================
!=======================================================================
FUNCTION AK_FFATM_WEIS80(t_k, s)
! Calculate f = k0(1-pH2O)*correction term for non-ideality
! in (mol/kg-SW)/atmosphere
! References: Weiss & Price (1980, Mar. Chem., 8, 347-359
! Eq 13 with table 6 values)
! Note : currently no pressure correction
IMPLICIT NONE
REAL(KIND=wp) :: AK_FFATM_WEIS80
! ------------------
! Argument variables
! ------------------
! s : salinity
! t_k : temperature in K
REAL(KIND=wp), INTENT(IN) :: t_k
REAL(KIND=wp), INTENT(IN) :: s
! ---------------
! Local variables
! ---------------
! zt_k_o_100 : zt_k/100
REAL(KIND=wp) :: t_k_o_100
REAL(KIND=wp) :: t_k_o_100_2
t_k_o_100 = t_k/hundred
t_k_o_100_2 = t_k_o_100*t_k_o_100
AK_FFATM_WEIS80 &
= exp(-162.8301_wp + 218.2968_wp/t_k_o_100 &
+ 90.9241_wp*log(t_k_o_100) - 1.47696_wp*t_k_o_100_2 &
+ s * (.025695_wp - .025225_wp*t_k_o_100 &
+ 0.0049867_wp*t_k_o_100_2))
RETURN
END FUNCTION AK_FFATM_WEIS80
!=======================================================================
!=======================================================================
FUNCTION AK_FFOCE_WEIS74(t_k, s)
! Calculate Fugacity Factor needed for non-ideality in ocean
! in [(mol/kg-SW)/atm]
! References: Weiss (1974) Marine Chemistry
! pH scale : N/A
! Note : currently no pressure correction
IMPLICIT NONE
REAL(KIND=wp) :: AK_FFOCE_WEIS74
! ------------------
! Argument variables
! ------------------
! s : salinity
! t_k : temperature in K
REAL(KIND=wp), INTENT(IN) :: t_k
REAL(KIND=wp), INTENT(IN) :: s
! ---------------
! Local variables
! ---------------
! zt_k_o_100 : zt_k/100
REAL(KIND=wp) :: zt_k_o_100
REAL(KIND=wp) :: delta
REAL(KIND=wp) :: B1
REAL(KIND=wp) :: B
zt_k_o_100 = t_k/100.0_wp
delta = (57.7_wp - 0.118_wp*t_k)
B1 = -1636.75_wp + 12.0408_wp*t_k - 0.0327957_wp*t_k*t_k
B = B1 + 3.16528_wp*t_k*t_k*t_k*1.e-5_wp
! "x2" term often neglected (assumed=1) in applications of Weiss (1974) eq.9
! x2 = 1 - x1 = 1 - xCO2 (it is very close to 1, but not quite)
AK_FFOCE_WEIS74 &
= exp( (B+two*delta) * p_bar_oneatmosphere / &
(gasconst_bar_cm3_o_mol_k*t_k))
RETURN
END FUNCTION AK_FFOCE_WEIS74
!=======================================================================
!!=======================================================================
! FUNCTION AK_CARB_0_WEIS74(t_k, s)
!
!! Function calculates K0 in (mol/kg-SW)/atmosphere
!
!! References: Weiss (1979) [(mol/kg-SW)/atm]
!! pH scale : N/A
!! Note : currently no pressure correction
! IMPLICIT NONE
! REAL(KIND=wp) :: AK_CARB_0_WEIS74
!
!! ------------------
!! Argument variables
!! ------------------
!! s : salinity
!! t_k : temperature in K
! REAL(KIND=wp), INTENT(IN) :: t_k
! REAL(KIND=wp), INTENT(IN) :: s
!
!! ---------------
!! Local variables
!! ---------------
!! zt_k_o_100 : zt_k/100
! REAL(KIND=wp) :: zt_k_o_100
!
! zt_k_o_100 = t_k/hundred
!
! AK_CARB_0_WEIS74 &
! = EXP( -60.2409_wp + 93.4517_wp/zt_k_o_100 &
! + 23.3585_wp*LOG(zt_k_o_100) &
! + ( 0.023517_wp - 0.023656_wp*zt_k_o_100 &
! + 0.0047036_wp*zt_k_o_100*zt_k_o_100)*s )
!
! RETURN
! END FUNCTION AK_CARB_0_WEIS74
!!=======================================================================
!=======================================================================
SUBROUTINE CALC_PCO2(theta,salt,dic,alk,po4,sit, &
ph,pco2oce,co3,hco3,co2aq)
!General parameters
! dictot = total inorgani!carbon (mol/m^3)
! where 1 T = 1 metri!ton = 1000 kg
! alktot = total alkalinity (eq/m^3)
! po4tot = inorganic phosphate (mol/^3)
! siltot = inorganic silicate (mol/^3)
! t = temperature (degrees C)
! s = salinity (PSU)
REAL(KIND=wp), INTENT(IN) :: theta, salt
REAL(KIND=wp), INTENT(IN) :: dic, alk, po4, sit
REAL(KIND=wp), INTENT(INOUT) :: ph
REAL(KIND=wp), INTENT(OUT) :: pco2oce, co3, hco3, co2aq
! Local variables
REAL(KIND=wp) hini, z_val, hnew
REAL(KIND=wp) bor, nh4, h2s, so4, flu
nh4 = zero
h2s = zero
bor = A_BTOT_SALIN (salt)
so4 = A_SO4TOT_SALIN(salt)
flu = A_FTOT_SALIN (salt)
hini = ten**(-one * ph)
hnew = SOLVE_AT_GENERAL(alk, dic, bor, po4, sit, nh4, h2s, &
so4, flu, p_hini=hini, p_val=z_val)
!Return update pH to main routine
ph = -log10(hnew)
!now determine [CO2*], HCO3- and CO32- , carbonate ion concentration
CALL SPECIATION_DIC(dic,hnew,co2aq,hco3,co3)
! get K0 and fugacity
CALL SETUP_FLUXCOEFFS(t_k_zerodegc + theta, salt)
! z_fco2 = z_co2aq/z_k0
! co2aq will be in mol/m3, convert to mol/kg to use with K0 and ff
pco2oce = co2aq*permil/(api0_dic*apiff_oce)
RETURN
END SUBROUTINE CALC_PCO2
!=======================================================================
!=======================================================================
SUBROUTINE CARBON_FLUXES(theta,salt,dic,alk,po4,si, &
ph,pco2atmos,wind,fopen,pressure, &
pco2ocean,fluxCO2)
!Calculate air-sea CO2 flux
! Argument variables
REAL(KIND=wp), INTENT(IN), DIMENSION(nbox) :: theta, &
salt, &
dic, &
alk, &
po4, &
si
REAL(KIND=wp), INTENT(IN), DIMENSION(nbox) :: wind, &
fopen, &
pressure
REAL(KIND=wp), INTENT(INOUT), DIMENSION(nbox) :: ph
REAL(KIND=wp), INTENT(OUT), DIMENSION(nbox) :: pco2ocean, &
fluxCO2
REAL(KIND=wp), INTENT(IN) :: pco2atmos
! Local variables
REAL(KIND=wp), DIMENSION(nbox) :: schmidtDIC, Kwexch
REAL(KIND=wp), DIMENSION(nbox) :: co3, hco3, co2aq
INTEGER :: i
! Initialize
pco2ocean = 0._wp
fluxCO2 = 0._wp
schmidtDIC = 0._wp
Kwexch = 0._wp
co3 = 0._wp
hco3 = 0._wp
co2aq = 0._wp
! calculate SCHMIDT NO. for CO2 (4th order, Wanninkhof 2014)
schmidtDIC = 2116.8_wp &
- 136.25_wp * theta &
+ 4.7353_wp * theta * theta &
- 0.092307_wp * theta * theta * theta &
+ 7.555e-4_wp * theta * theta * theta * theta
Kwexch = (Kwexch_av * conv_cmhr_ms * wind*wind * fopen ) &
/ sqrt(schmidtDIC/660._wp)
do i = 1,nbox
! calculate surface coefficients
CALL SETUP_API4PHSWS( t_k_zerodegc + theta(i), &
salt(i), &
pressure(i))
CALL SETUP_FLUXCOEFFS(t_k_zerodegc + theta(i), &
salt(i))
CALL CALC_PCO2(theta(i), &
salt(i), &
dic(i), &
alk(i), &
po4(i), &
si(i), &
ph(i), &
pco2ocean(i), &
co3(i), &
hco3(i), &
co2aq(i))
fluxCO2(i) = Kwexch(i)*( &
pco2atmos * apiff_atm - &
pco2ocean(i) * apiff_oce &
* api0_dic )
end do
fluxCO2 = fluxCO2 * conv_molkg_molm3
RETURN
END SUBROUTINE CARBON_FLUXES
!=======================================================================
!=======================================================================
SUBROUTINE CALC_ATMOS_PCO2(atmos_moles,atmos_carbon,netCO2flux, &
pco2atm)
!Integrate atmospheri!carbon content
! Argument variables
REAL(KIND=wp), INTENT(IN) :: atmos_moles, netCO2flux
REAL(KIND=wp), INTENT(INOUT):: pco2atm, atmos_carbon
! How much carbon (moles) is currently in the atmosphere
! atmos_carbon=atmos_moles*pco2atm
! What is the change resulting from air-sea flux in surface boxes
atmos_carbon=atmos_carbon-netCO2flux
! Update atmospheric CO2 level
pco2atm = atmos_carbon/atmos_moles
RETURN
END SUBROUTINE CALC_ATMOS_PCO2
!=======================================================================
END MODULE MOD_CARBONCHEM