Soil constant definitions (STEMMUS)

[AlbyDR]

2. Soil constant definition (STEMMUS)

2.1 getSoilConstants file (~/src/+io/)

2.2 define_constants file (~/src/+io/)

2.3 getModelSettings file (~/src/+io/)

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2.1 getSoilConstants file (~/src/+io/)

symbol	variable long name	short definition	unit	default value	value range	observation
hd			[-]	-1e7
hm			[-]	-9899
CHST			[-]	0
Elmn_Lnth			[-]	0
Dmark			[-]	0
Phi_S			[-]	[-17.9 -17 -17 -19 -10 -10]
Phi_soc			[-]	-0.0103
Lamda_soc			[-]	2.7
Theta_soc			[-]	0.6
XK			[-]	0.025		XK=0.11 for silt loam and XK = 0.025 for sand, the SoilConstants.XK is used in updateSoilVariables

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2.2 define_constants file (~/src/+io/)

symbol	variable long name	short definition	unit	default value	value range	observation
A	Constant of Avogadro		[mol-1]	6.02214E23
h	Plancks constant		[J s]	6.6262E-34
c	Speed of light		[m s-1]	299792458
cp	Specific heat of dry air		[J kg-1 K-1]	1004
cp_specific	specific heat at cte pressure		[MJ.kg-1.C-1]	1.013E-3		FAO56 p26 box6
R	Molar gas constant		[J mol-1K-1]	8.314
R_specific	specific gas		[kJ.kg-1.K-1]	0.287		FAO56 p26 box6
rhoa	Specific mass of air		[kg m-3]	1.2047
kappa	Von Karman constant		[-]	0.4
MH2O	Molecular mass of water		[g mol-1]	18
Mair	Molecular mass of dry air		[g mol-1]	28.96
MCO2	Molecular mass of carbon dioxide		[g mol-1]	44
sigmaSB	Stefan Boltzman constant		[W m-2 K-4]	5.67E-8
deg2rad	Conversion from deg to rad		[rad]	pi / 180
C2K	Melting point of water		[K]	273.15
CKTN		Constant used in calculating viscosity factor for hydraulic conductivity	[-]	(50 + 2.575*20)
l	Coefficient in VG mode		[-]	0.5
g	Gravity acceleration		[cm s-2]	981
RHOL	Water density		[g cm-3]	1
RHOI	Ice density		[g cm-3]	0.92
Rv	Gas constant for vapor		[cm2 s-2 Cels-1]	461.5*1e4		(original J.kg^-1.Cels^-1)
RDA	Gas constant for dry air		[cm2 s-2 Cels-1]	287.1*1e4		(original J.kg^-1.Cels^-1)
RHO_bulk	Bulk density of sand		[g cm-3]	1.25
Hc	Henry's constant		[-]	0.02
GWT		The gain factor(dimensionless), which assesses the temperature	[-]	7		dependence of the soil water retention curve is set as 7 for % sand (Noborio et al, 1996)
MU_a	Viscosity of air		[g cm-1 s-1]	1.846*10^(-4)		(original 1.846*10^(-5)kg.m^-1.s^-1)
Gamma0		The surface tension of soil water at 25 Cels degree	[g s-2]	71.89
Gamma_w	Specific weight of water		[g cm-2 s-2]	const.RHOL*const.g
Lambda1	Coefficients in thermal conductivity		[-]	0.228/100
Lambda2		From HYDRUS1D heat transport parameter (Chung Hortan 1987 WRR)	[W m-1 Cels-1] (1 W.s=J)	-2.406/100
Lambda3			[-]	4.909/100
MU_W0	Viscosity of water at reference temperature		[g cm-1 s-1]	2.4152*10^(-4)		(original2.4152*10^(-5)kg.m^-1.s^-1)
MU1	Coefficient for calculating viscosity of water		[J mol-1]	4742.8
b	Coefficient for calculating viscosity of water		[cm]	4*10^(-6)
W0	Coefficient for calculating differential heat of wetting by Milly's method		[-]	1.001*10^3
c_L	Specific heat capacity of liquid water		[J/g-1/Cels-1]	4.186		Notice the original unit is 4186kg^-1
c_V	Specific heat capacity of vapor		[J/g-1/Cels-1]	1.870
c_a	Specific heat capacity of dry air		[J/g-1/Cels-1]	1.005
c_i	Specific heat capacity of ice		[J/g-1/Cels-1]	2.0455
lambdav	atent heat of evaporation		[MJ.kg-1]	2.45		l FAO56 pag 31
k	karman's		[-]	0.41		cte FAO 56 Eq4

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2.3 getModelSettings file (~/src/+io/)

symbol	variable long name	short definition	unit	default value	value range	observation
R_depth	root depth		[cm]	350		the dynamic root growth is closed, and an empirical and pre-defined root distribution function is used, see here. This works on forest sites but may have some uncertainties in cropland. To reduce the uncertainties, a dynamic root growth option is provided, but it might need to be adjusted according to the actual condition of the site.
J		index of soil type for choosing soil physical parameters	[-]	1
SWCC		soil water characteristic curve, 0 for Clapp and Hornberger and 1 for Van Gen	[0,1]	1
Hystrs		considers hysteresis if the value is 1, otherwise 0	[0,1]	0
Thmrlefc		considers the isothermal water flow if the value is 0, otherwise 1	[0,1]	1
Soilairefc		considers dry air transport if the value is 1, otherwise 0	[0,1]	0
hThmrl		a special calculation of water capacity is used if the value is 1, otherwise 0	[0,1]	1
W_Chg		calculates the heat of wetting by Millys method if 0 and by Lyle Pruntys method if 1	[0,1]	1
ThmrlCondCap		Millys effective thermal capacity and conductivity formulation to verify the vapor and heat transport in extremly dry soil	[0,1]	1
ThermCond		effective thermal conductivity methods, 1 for De Vries, 2 for Jonhansen, 3 for simplified De Vries (Tian 2016) or 4 for Farouki	[1,2,2,4]	1
SSUR	soil-texture-related parameters	surface area, for loam 10^5 or for sand 10^2 (cm^-1)	[cm-1]	10^2		The parameter is determined by the two soil texture definition (loam or sand)
fc	soil-texture-related parameters	fraction of clay, for loam 0.036; for sand 0.02	[?]	0.02		The parameter is determined by the two soil texture definition (loam or sand)
Tr		reference temperature	[°C]	20		Constant
T0		reference temperature	[k]	273.15
rwuef			[-]	1
rroot	radius of the root		[m]	1.5*1e-3		The constant can change with different species or plant function types, see STEMMUS-SCOPE v1.0.0 paper (Appendix B Table B1) .
SFCC			[-]	1
Tot_Depth		other settings, Tot_Depth [cm], it should be usually bigger than 0.5m	[cm]	500
Eqlspace		the space step equal or not, for 0 the DeltZ would be reset in 50cm by hand	[0,1]	0
NS		number of soil types	[n] types	1
NIT		time and domain information setting, desirable number of iterations in a time step	[n] interactions	30
KT		time and domain information setting, number of time steps	[n] steps	0
NL		determination of NL, the number of elements	[n] elements	100

[Crystal-szj]

Hi @AlbyDR, thank you very much for your efforts. In terms of your questions about the default value of parameters, they can be changed according to your sites.

R_depth is the root depth. In the default version, the dynamic root growth is closed, and we use an empirical and pre-defined root distribution function, see here. This works on forest sites but may have some uncertainties in cropland. To reduce the uncertainties, a dynamic root growth option is provided, but it might need to be adjusted according to the actual condition of the site.
SSUR and fc are soil-texture-related parameters. Once the soil texture is defined, the two parameters are determined.
Tr is the reference temperature ($^\circ C$), it is a constant.
rroot is the radius of the root (m). It can change with different species or plant function types, see STEMMUS-SCOPE v1.0.0 paper (Appendix B Table B1) .

If you have further questions, feel free to let me know.

Reference:
Wang, Y., Zeng, Y., Yu, L., Yang, P., Van der Tol, C., Yu, Q., Lü, X., Cai, H., & Su, Z. (2021). Integrated modeling of canopy photosynthesis, fluorescence, and the transfer of energy, mass, and momentum in the soil–plant–atmosphere continuum (STEMMUS–SCOPE v1.0.0). Geoscientific Model Development, 14, 1379-1407

Best regards,
Zengjing