Soil thermodynamic functions

Functions soil_thermalConductivity and soil_thermalCapacity calculate thermal conductivity and thermal capacity for each soil layer, given its texture and water content. Functions soil_temperatureGradient and soil_temperatureChange are used to calculate soil temperature gradients (in ºC/m) and temporal temperature change (in ºC/s) given soil layer texture and water content (and possibly including heat flux from above).

soil_thermalCapacity(soil, model = "SX")

soil_thermalConductivity(soil, model = "SX")

soil_temperatureGradient(dVec, Temp)

soil_temperatureChange(
  dVec,
  Temp,
  sand,
  clay,
  W,
  Theta_SAT,
  Theta_FC,
  Gdown,
  tstep
)

Arguments

soil

Soil object (returned by function soil).

model

Either 'SX' or 'VG' for Saxton's or Van Genuchten's pedotransfer models.

dVec

Width of soil layers (in mm).

Temp

Temperature (in ºC) for each soil layer.

sand

Percentage of sand (in percent weight) for each layer.

clay

Percentage of clay (in percent weight) for each layer.

W

Soil moisture (in percent of field capacity) for each layer.

Theta_SAT

Relative water content (in percent volume) at saturation for each layer.

Theta_FC

Relative water content (in percent volume) at field capacity for each layer.

Gdown

Downward heat flux from canopy to soil (in W·m-2).

tstep

Time step (interval) in seconds.

Value

Function soil_thermalConductivity returns a vector with values of thermal conductivity (W/m/ºK) for each soil layer.

Function soil_thermalCapacity returns a vector with values of heat storage capacity (J/m3/ºK) for each soil layer.

Function soil_temperatureGradient returns a vector with values of temperature gradient between consecutive soil layers.

Function soil_temperatureChange returns a vector with values of instantaneous temperature change (ºC/s) for each soil layer.

References

Cox, P.M., Betts, R.A., Bunton, C.B., Essery, R.L.H., Rowntree, P.R., and Smith, J. 1999. The impact of new land surface physics on the GCM simulation of climate and climate sensitivity. Climate Dynamics 15: 183–203.

Dharssi, I., Vidale, P.L., Verhoef, A., MacPherson, B., Jones, C., and Best, M. 2009. New soil physical properties implemented in the Unified Model at PS18. 9–12.

See also

soil

Author

Miquel De Cáceres Ainsa, CREAF

Examples

examplesoil = soil(defaultSoilParams())
soil_thermalConductivity(examplesoil)
#> [1] 2.2 2.2 2.2 2.2
soil_thermalCapacity(examplesoil)
#> [1] 2486214 2486214 2486214 2486214

#Values change when altering water content (drier layers have lower conductivity and capacity)
examplesoil$W = c(0.1, 0.4, 0.7, 1.0)
soil_thermalConductivity(examplesoil)
#> [1] 0.4266171 1.4943000 1.9252995 2.2000000
soil_thermalCapacity(examplesoil)
#> [1] 1342121 1723486 2104850 2486214