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Add a new snow thermal conductivity calculation to ELM #6524

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merged 6 commits into from
Aug 21, 2024
Merged

Add a new snow thermal conductivity calculation to ELM #6524

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ef08ba7
Added new snow Thermal Conductivity in SoilTemperatureMod.F90
chloewhicker Jun 13, 2024
2b7fbc0
changed flag name for new snow thk flag to be more descriptive
chloewhicker Jun 20, 2024
7af3988
clean up master & feature branch merge
chloewhicker Jul 19, 2024
c221955
removed testing write statements
chloewhicker Jul 24, 2024
a4e9c06
minor stylistic / precision mods
chloewhicker Aug 16, 2024
04258da
minor stylistic change
chloewhicker Aug 20, 2024
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4 changes: 4 additions & 0 deletions components/elm/bld/namelist_files/namelist_definition.xml
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Expand Up @@ -766,6 +766,10 @@ This option enables more realistic
snowpack conditions on glaciers and ice sheets, including a semi-empirical
firn densification model. uses the same physics as use_extrasnowlayers but
uses the original 5 snow layer scheme

<entry id="use_T_rho_dependent_snowthk" type="logical" category="physics"
group="elm_inparm" valid_values="" value=".false.">
Toggle to use new snow thermal conductivity that relies on snow temperature and density.
</entry>

<entry id="use_noio" type="logical" category="default_settings"
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52 changes: 44 additions & 8 deletions components/elm/src/biogeophys/SoilTemperatureMod.F90
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Expand Up @@ -834,7 +834,7 @@ subroutine SoilThermProp (bounds, num_nolakec, filter_nolakec, &
use elm_varcon , only : denh2o, denice, tfrz, tkwat, tkice, tkair, cpice, cpliq, thk_bedrock
use landunit_varcon , only : istice, istice_mec, istwet
use column_varcon , only : icol_roof, icol_sunwall, icol_shadewall, icol_road_perv, icol_road_imperv
use elm_varctl , only : iulog
use elm_varctl , only : iulog, use_T_rho_dependent_snowthk
!
! !ARGUMENTS:
type(bounds_type) , intent(in) :: bounds
Expand All @@ -847,7 +847,7 @@ subroutine SoilThermProp (bounds, num_nolakec, filter_nolakec, &
type(soilstate_type) , intent(inout) :: soilstate_vars
!
! !LOCAL VARIABLES:
integer :: l,c,j ! indices
integer :: l,c,j,i ! indices
integer :: nlevbed ! # levels to bedrock
integer :: fc ! lake filtered column indices
real(r8) :: dksat ! thermal conductivity for saturated soil (j/(k s m))
Expand All @@ -856,6 +856,17 @@ subroutine SoilThermProp (bounds, num_nolakec, filter_nolakec, &
real(r8) :: satw ! relative total water content of soil.
real(r8) :: zh2osfc
character(len=64) :: event

real(r8), parameter :: rho_ice = 917._r8
real(r8) :: k_snw_vals(5)
real(r8) :: k_snw_tmps(5)
real(r8) :: k_snw_coe1(5)
real(r8) :: k_snw_coe2(5)
real(r8) :: k_snw_coe3(5)
data k_snw_tmps(:) /223.0_r8, 248.0_r8, 263.0_r8, 268.0_r8, 273.0_r8/
data k_snw_coe1(:) /2.564_r8,2.172_r8,1.985_r8,1.883_r8,1.776_r8/
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data k_snw_coe2(:) /-0.059_r8, 0.015_r8, 0.073_r8, 0.107_r8, 0.147_r8/
data k_snw_coe3(:) /0.0205_r8, 0.0252_r8, 0.0336_r8, 0.0386_r8, 0.0455_r8/
!-----------------------------------------------------------------------
event = 'SoilThermProp'
call t_start_lnd( event )
Expand Down Expand Up @@ -943,14 +954,39 @@ subroutine SoilThermProp (bounds, num_nolakec, filter_nolakec, &
endif
endif
endif

if (use_T_rho_dependent_snowthk) then ! choose which snow thermal conductivity to use
if (snl(c)+1 < 1 .AND. (j >= snl(c)+1) .AND. (j <= 0)) then
bw(c,j) = (h2osoi_ice(c,j) + h2osoi_liq(c,j)) / (frac_sno(c) * dz(c,j))

do i = 1, 5
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k_snw_vals(i) = k_snw_coe1(i) * (bw(c,j) / rho_ice)**2 - k_snw_coe2(i) * (bw(c,j) / rho_ice) + k_snw_coe3(i)
end do

do i = 1, size(k_snw_tmps) - 1
if (k_snw_tmps(i) <= t_soisno(c,j) .and. t_soisno(c,j) <= k_snw_tmps(i + 1)) then
thk(c,j) = k_snw_vals(i) + (t_soisno(c,j) - k_snw_tmps(i)) * (k_snw_vals(i + 1)-k_snw_vals(i)) / (k_snw_tmps(i + 1) - k_snw_tmps(i))
end if
end do

! Thermal conductivity of snow, which from Jordan (1991) pp. 18
! Only examine levels from snl(c)+1 -> 0 where snl(c) < 1
if (snl(c)+1 < 1 .AND. (j >= snl(c)+1) .AND. (j <= 0)) then
bw(c,j) = (h2osoi_ice(c,j)+h2osoi_liq(c,j))/(frac_sno(c)*dz(c,j))
thk(c,j) = tkair + (7.75e-5_r8 *bw(c,j) + 1.105e-6_r8*bw(c,j)*bw(c,j))*(tkice-tkair)
end if
! Handle edge cases if t_soisno(c,j) is outside the given range
if (t_soisno(c,j) < k_snw_tmps(1)) then
thk(c,j) = k_snw_vals(1)
else if (t_soisno(c,j) > k_snw_tmps(size(k_snw_tmps))) then
thk(c,j) = k_snw_vals(size(k_snw_tmps))
end if

end if


else
! Thermal conductivity of snow, which from Jordan (1991) pp. 18
! Only examine levels from snl(c)+1 -> 0 where snl(c) < 1
if (snl(c)+1 < 1 .AND. (j >= snl(c)+1) .AND. (j <= 0)) then
bw(c,j) = (h2osoi_ice(c,j)+h2osoi_liq(c,j))/(frac_sno(c)*dz(c,j))
thk(c,j) = tkair + (7.75e-5_r8 *bw(c,j) + 1.105e-6_r8*bw(c,j)*bw(c,j))*(tkice-tkair)
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Same comment as above regarding consistent use of spaces.

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Please space consistently here too.

end if
endif
end do
end do

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4 changes: 3 additions & 1 deletion components/elm/src/main/controlMod.F90
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Expand Up @@ -285,7 +285,7 @@ subroutine control_init( )
use_nofire, use_lch4, use_vertsoilc, use_extralakelayers, &
use_vichydro, use_century_decomp, use_cn, use_crop, use_snicar_frc, &
use_snicar_ad, use_firn_percolation_and_compaction, use_extrasnowlayers,&
use_vancouver, use_mexicocity, use_noio
use_T_rho_dependent_snowthk, use_vancouver, use_mexicocity, use_noio

! cpl_bypass variables
namelist /elm_inparm/ metdata_type, metdata_bypass, metdata_biases, &
Expand Down Expand Up @@ -727,6 +727,7 @@ subroutine control_spmd()
call mpi_bcast (use_extralakelayers, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_extrasnowlayers, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_firn_percolation_and_compaction, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_T_rho_dependent_snowthk, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_vichydro, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_century_decomp, 1, MPI_LOGICAL, 0, mpicom, ier)
call mpi_bcast (use_cn, 1, MPI_LOGICAL, 0, mpicom, ier)
Expand Down Expand Up @@ -1031,6 +1032,7 @@ subroutine control_print ()
write(iulog,*) ' use_extralakelayers = ', use_extralakelayers
write(iulog,*) ' use_extrasnowlayers = ', use_extrasnowlayers
write(iulog,*) ' use_firn_percolation_and_compaction = ', use_firn_percolation_and_compaction
write(iulog,*) ' use_T_rho_dependent_snowthk = ', use_T_rho_dependent_snowthk
write(iulog,*) ' use_vichydro = ', use_vichydro
write(iulog,*) ' use_century_decomp = ', use_century_decomp
write(iulog,*) ' use_cn = ', use_cn
Expand Down
1 change: 1 addition & 0 deletions components/elm/src/main/elm_varctl.F90
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Expand Up @@ -380,6 +380,7 @@ module elm_varctl
logical, public :: use_mexicocity = .false.
logical, public :: use_noio = .false.
logical, public :: use_var_soil_thick = .false.
logical, public :: use_T_rho_dependent_snowthk = .false.
logical, public :: use_atm_downscaling_to_topunit = .false.
character(len = SHR_KIND_CS), public :: precip_downscaling_method = 'ERMM' ! Precip downscaling method values can be ERMM or FNM
logical, public :: use_lake_wat_storage = .false.
Expand Down
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