! SUMMA - Structure for Unifying Multiple Modeling Alternatives
! Copyright (C) 2014-2020 NCAR/RAL; University of Saskatchewan; University of Washington
!
! This file is part of SUMMA
!
! For more information see: http://www.ral.ucar.edu/projects/summa
!
! This program is free software: you can redistribute it and/or modify
! it under the terms of the GNU General Public License as published by
! the Free Software Foundation, either version 3 of the License, or
! (at your option) any later version.
!
! This program 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 General Public License for more details.
!
! You should have received a copy of the GNU General Public License
! along with this program. If not, see <http://www.gnu.org/licenses/>.
module updatState_module
USE nrtype
! physical constants
USE multiconst,only:&
Tfreeze, & ! freezing point of pure water (K)
iden_air, & ! intrinsic density of air (kg m-3)
iden_ice, & ! intrinsic density of ice (kg m-3)
iden_water, & ! intrinsic density of water (kg m-3)
gravity, & ! gravitational acceleteration (m s-2)
LH_fus ! latent heat of fusion (J kg-1)
implicit none
private
public::updateSnow
public::updateSoil
contains
! *************************************************************************************************************
! public subroutine updateSnow: compute phase change impacts on volumetric liquid water and ice
! *************************************************************************************************************
subroutine updateSnow(&
! input
mLayerTemp ,& ! intent(in): temperature (K)
mLayerTheta ,& ! intent(in): volume fraction of total water (-)
snowfrz_scale ,& ! intent(in): scaling parameter for the snow freezing curve (K-1)
! output
mLayerVolFracLiq ,& ! intent(out): volumetric fraction of liquid water (-)
mLayerVolFracIce ,& ! intent(out): volumetric fraction of ice (-)
fLiq ,& ! intent(out): fraction of liquid water (-)
err,message) ! intent(out): error control
! utility routines
USE snow_utils_module,only:fracliquid ! compute volumetric fraction of liquid water
implicit none
! input variables
real(dp),intent(in) :: mLayerTemp ! temperature (K)
real(dp),intent(in) :: mLayerTheta ! volume fraction of total water (-)
real(dp),intent(in) :: snowfrz_scale ! scaling parameter for the snow freezing curve (K-1)
! output variables
real(dp),intent(out) :: mLayerVolFracLiq ! volumetric fraction of liquid water (-)
real(dp),intent(out) :: mLayerVolFracIce ! volumetric fraction of ice (-)
real(dp),intent(out) :: fLiq ! fraction of liquid water (-)
! error control
integer(i4b),intent(out) :: err ! error code
character(*),intent(out) :: message ! error message
! initialize error control
err=0; message="updateSnow/"
! compute the volumetric fraction of liquid water and ice (-)
fLiq = fracliquid(mLayerTemp,snowfrz_scale)
mLayerVolFracLiq = fLiq*mLayerTheta
mLayerVolFracIce = (1._dp - fLiq)*mLayerTheta*(iden_water/iden_ice)
!print*, 'mLayerTheta - (mLayerVolFracIce*(iden_ice/iden_water) + mLayerVolFracLiq) = ', mLayerTheta - (mLayerVolFracIce*(iden_ice/iden_water) + mLayerVolFracLiq)
!write(*,'(a,1x,4(f20.10,1x))') 'in updateSnow: fLiq, mLayerTheta, mLayerVolFracIce = ', &
! fLiq, mLayerTheta, mLayerVolFracIce
!pause
end subroutine updateSnow
! *************************************************************************************************************
! public subroutine updateSoil: compute phase change impacts on matric head and volumetric liquid water and ice
! *************************************************************************************************************
subroutine updateSoil(&
! input
mLayerTemp ,& ! intent(in): temperature vector (K)
mLayerMatricHead ,& ! intent(in): matric head (m)
vGn_alpha ,& ! intent(in): van Genutchen "alpha" parameter
vGn_n ,& ! intent(in): van Genutchen "n" parameter
theta_sat ,& ! intent(in): soil porosity (-)
theta_res ,& ! intent(in): soil residual volumetric water content (-)
vGn_m ,& ! intent(in): van Genutchen "m" parameter (-)
! output
mLayerVolFracWat ,& ! intent(out): volumetric fraction of total water (-)
mLayerVolFracLiq ,& ! intent(out): volumetric fraction of liquid water (-)
mLayerVolFracIce ,& ! intent(out): volumetric fraction of ice (-)
err,message) ! intent(out): error control
! utility routines
USE soil_utils_module,only:volFracLiq ! compute volumetric fraction of liquid water based on matric head
USE soil_utils_module,only:matricHead ! compute the matric head based on volumetric liquid water content
implicit none
! input variables
real(dp),intent(in) :: mLayerTemp ! estimate of temperature (K)
real(dp),intent(in) :: mLayerMatricHead ! matric head (m)
real(dp),intent(in) :: vGn_alpha ! van Genutchen "alpha" parameter
real(dp),intent(in) :: vGn_n ! van Genutchen "n" parameter
real(dp),intent(in) :: theta_sat ! soil porosity (-)
real(dp),intent(in) :: theta_res ! soil residual volumetric water content (-)
real(dp),intent(in) :: vGn_m ! van Genutchen "m" parameter (-)
! output variables
real(dp),intent(out) :: mLayerVolFracWat ! fractional volume of total water (-)
real(dp),intent(out) :: mLayerVolFracLiq ! volumetric fraction of liquid water (-)
real(dp),intent(out) :: mLayerVolFracIce ! volumetric fraction of ice (-)
integer(i4b),intent(out) :: err ! error code
character(*),intent(out) :: message ! error message
! define local variables
real(dp) :: TcSoil ! critical soil temperature when all water is unfrozen (K)
real(dp) :: xConst ! constant in the freezing curve function (m K-1)
real(dp) :: mLayerPsiLiq ! liquid water matric potential (m)
! initialize error control
err=0; message="updateSoil/"
! compute fractional **volume** of total water (liquid plus ice)
mLayerVolFracWat = volFracLiq(mLayerMatricHead,vGn_alpha,theta_res,theta_sat,vGn_n,vGn_m)
if(mLayerVolFracWat > theta_sat)then; err=20; message=trim(message)//'volume of liquid and ice exceeds porosity'; return; end if
! compute the critical soil temperature where all water is unfrozen (K)
! (eq 17 in Dall'Amico 2011)
TcSoil = Tfreeze + min(mLayerMatricHead,0._dp)*gravity*Tfreeze/LH_fus ! (NOTE: J = kg m2 s-2, so LH_fus is in units of m2 s-2)
! *** compute volumetric fraction of liquid water and ice for partially frozen soil
if(mLayerTemp < TcSoil)then ! (check if soil temperature is less than the critical temperature)
! - volumetric liquid water content (-)
! NOTE: mLayerPsiLiq is the liquid water matric potential from the Clapeyron equation, used to separate the total water into liquid water and ice
! mLayerPsiLiq is DIFFERENT from the liquid water matric potential used in the flux calculations
xConst = LH_fus/(gravity*Tfreeze) ! m K-1 (NOTE: J = kg m2 s-2)
mLayerPsiLiq = xConst*(mLayerTemp - Tfreeze) ! liquid water matric potential from the Clapeyron eqution
mLayerVolFracLiq = volFracLiq(mLayerPsiLiq,vGn_alpha,theta_res,theta_sat,vGn_n,vGn_m)
! - volumetric ice content (-)
mLayerVolFracIce = mLayerVolFracWat - mLayerVolFracLiq
! *** compute volumetric fraction of liquid water and ice for unfrozen soil
else
! all water is unfrozen
mLayerPsiLiq = mLayerMatricHead
mLayerVolFracLiq = mLayerVolFracWat
mLayerVolFracIce = 0._dp
end if ! (check if soil is partially frozen)
end subroutine updateSoil
end module updatState_module