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Introduce namelist option for thermal conductivity of snow: Jordan vs. Sturm #2148

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AdrienDams wants to merge 7 commits into from
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Introduce namelist option for thermal conductivity of snow: Jordan vs. Sturm #2148

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ab94ab4
Replace thermal conductivity of snow of Jordan with Sturm
AdrienDams Sep 8, 2023
08623c7
Merge remote-tracking branch 'escomp/master' into pr2148_sturm_v_jordan
slevis-lmwg Oct 30, 2023
37db306
Update comments, add placeholder for thermal_cond_snow option
slevis-lmwg Oct 30, 2023
75d5f10
Add new namelist variable snow_thermal_cond_method (not tested)
slevis-lmwg Nov 1, 2023
239a552
Change snow_thermal_cond_method to char*25
slevis-lmwg Nov 3, 2023
dc0910f
Merge tag 'ctsm5.1.dev148' into pr2148_sturm_v_jordan
slevis-lmwg Nov 3, 2023
b626e88
Small corrections for tests to run
slevis-lmwg Nov 3, 2023
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17 changes: 11 additions & 6 deletions src/biogeophys/SoilTemperatureMod.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,7 @@ module SoilTemperatureMod
! o The thermal conductivity of soil is computed from
! the algorithm of Johansen (as reported by Farouki 1981), and the
! conductivity of snow is from the formulation used in
! SNTHERM (Jordan 1991).
! Sturm (1997).
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@wwieder wwieder Sep 8, 2023

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Why is there so much documentation in the code itself here? If we keep all the notes (here and below) snow conductivity should reference both Jordan and Sturm papers.

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@slevis-lmwg slevis-lmwg Oct 30, 2023

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Half of the notes here and below are about the thermal conductivity of soil, so I will keep them and reference both papers.

! o Boundary conditions:
! F = Rnet - Hg - LEg (top), F= 0 (base of the soil column).
! o Soil / snow temperature is predicted from heat conduction
Expand Down Expand Up @@ -100,7 +100,7 @@ subroutine SoilTemperature(bounds, num_urbanl, filter_urbanl, num_urbanc, filter
! o The thermal conductivity of soil is computed from
! the algorithm of Johansen (as reported by Farouki 1981), and the
! conductivity of snow is from the formulation used in
! SNTHERM (Jordan 1991).
! Sturm (1997).
! o Boundary conditions:
! F = Rnet - Hg - LEg (top), F= 0 (base of the soil column).
! o Soil / snow temperature is predicted from heat conduction
Expand Down Expand Up @@ -611,7 +611,7 @@ subroutine SoilThermProp (bounds, num_urbanc, filter_urbanc, num_nolakec, filter
!
! (2) The thermal conductivity of soil is computed from the algorithm of
! Johansen (as reported by Farouki 1981), and of snow is from the
! formulation used in SNTHERM (Jordan 1991).
! formulation used in Sturm (1997).
! The thermal conductivities at the interfaces between two neighboring
! layers (j, j+1) are derived from an assumption that the flux across
! the interface is equal to that from the node j to the interface and the
Expand Down Expand Up @@ -734,11 +734,16 @@ subroutine SoilThermProp (bounds, num_urbanc, filter_urbanc, num_nolakec, filter
endif
endif

! Thermal conductivity of snow, which from Jordan (1991) pp. 18
! Thermal conductivity of snow, which from Sturm (1997)
! 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)
bw(c,j) = ((h2osoi_ice(c,j)*1)+h2osoi_liq(c,j))/(frac_sno(c)*dz(c,j)) ! ==RHOS
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@wwieder wwieder Sep 8, 2023

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This line is actually is the same for both approaches.

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@slevis-lmwg slevis-lmwg Oct 30, 2023

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Returning line 740 to the original. Is the comment at the end ==RHOS helpful to keep?

! thk(c,j) = tkair + (7.75e-5_r8 *bw(c,j) + 1.105e-6_r8*bw(c,j)*bw(c,j))*(tkice-tkair) ! Original (Jordan) Parameterisation
if (bw(c,j) <= 156) then !LMW or 0.156 ?
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@wwieder wwieder Sep 8, 2023

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Here is where I think we'll want to use a namelist option to chose between Jornand and Sturm formulations for thk

thk(c,j) = 0.023 + 0.234*(bw(c,j)/1000) !LMW - units changed by VRD
else !LMW
thk(c,j) = 0.138 - 1.01*(bw(c,j)/1000) +(3.233*((bw(c,j)/1000)*(bw(c,j)/1000))) ! LMW Sturm I think
end if
end if

end do
Expand Down