Constants: Constants used in the DynACof package

In VEZY/DynACof: A Process-Based Model to Study Growth, Yield and Ecosystem Services of Coffee Agroforestry Systems

Description

Constants used in the DynACof package

Usage

Constants()

Value

This function defines the following constants:

Cp	specific heat of air for constant pressure (J K-1 kg-1), Source: Allen 1998 FAO Eq. 8 p. 32
pressure0	reference atmospheric pressure at sea level (Pa)
FPAR	Fraction of global radiation that is PAR (source: MAESPA model)
g	gravitational acceleration (m s-2)
Rd	gas constant of dry air (J kg-1 K-1), source : Foken p. 245
Rgas	universal gas constant (J mol-1 K-1)
Kelvin	conversion degree Celsius to Kelvin
vonkarman	von Karman constant (-)
MJ_to_W	coefficient to convert MJ into W (W MJ-1)
Gsc	solar constant (W m-2 = J m-2 s-1, ), source : Khorasanizadeh and Mohammadi (2016)
sigma	Stefan-Boltzmann constant (W m-2 K-4)
H2OMW	Conversion factor from kg to mol for H2O (kg mol-1)
W_umol	Conversion factor from watt to micromole for H2O (W µmol-1)
λ(lambda)	Latent heat of vaporization (MJ kgH2O-1)
cl	Drag coefficient per unit leaf area (m s-1)
Dheat	Molecular diffusivity for heat (m s-1)
GBVGBH	Conversion factor from conductance to water to conductance to heat.
M_H20	H2O molar mass (kg\\ mol^{-1})

Note

Values are partly burrowed from bigleaf::bigleaf.constants()

References

• Allen, R. G., et al. (1998). "Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and drainage paper 56." 300(9): D05109.

• Foken, T, 2008: Micrometeorology. Springer, Berlin, Germany.

• Khorasanizadeh, H. and K. Mohammadi (2016). "Diffuse solar radiation on a horizontal surface: Reviewing and categorizing the empirical models." Renewable and Sustainable Energy Reviews 53: 338-362.

See Also

DynACof()

VEZY/DynACof documentation built on Feb. 3, 2021, 8:52 p.m.