bigleaf.constants: Constants Used in the bigleaf Package

Description

This function defines the following constants:

Usage

bigleaf.constants(
  cp = 1004.834,
  Rgas = 8.31451,
  Rv = 461.5,
  Rd = 287.0586,
  Md = 0.0289645,
  Mw = 0.0180153,
  eps = 0.622,
  g = 9.81,
  solar_constant = 1366.1,
  pressure0 = 101325,
  Tair0 = 273.15,
  k = 0.41,
  Cmol = 0.012011,
  Omol = 0.0159994,
  H2Omol = 0.01801528,
  sigma = 5.670367e-08,
  Pr = 0.71,
  Sc_CO2 = 1.07,
  Le067 = 0.93,
  Kelvin = 273.15,
  DwDc = 1.6,
  days2seconds = 86400,
  kPa2Pa = 1000,
  Pa2kPa = 0.001,
  umol2mol = 1e-06,
  mol2umol = 1e+06,
  kg2g = 1000,
  g2kg = 0.001,
  kJ2J = 1000,
  J2kJ = 0.001,
  se_median = 1.253,
  frac2percent = 100
)

Arguments

cp: Specific heat of air for constant pressure (J K-1 kg-1)
Rgas: Universal gas constant (J mol-1 K-1)
Rv: Gas constant of water vapor (J kg-1 K-1) (Stull 1988 p.641)
Rd: Gas constant of dry air (J kg-1 K-1) (Foken p. 245)
Md: Molar mass of dry air (kg mol-1)
Mw: Molar mass of water vapor (kg mol-1)
eps: Ratio of the molecular weight of water vapor to dry air (=Mw/Md)
g: Gravitational acceleration (m s-2)
solar_constant: Solar constant (W m-2)
pressure0: Reference atmospheric pressure at sea level (Pa)
Tair0: Reference air temperature (K)
k: von Karman constant
Cmol: Molar mass of carbon (kg mol-1)
Omol: Molar mass of oxygen (kg mol-1)
H2Omol: Molar mass of water (kg mol-1)
sigma: Stefan-Boltzmann constant (W m-2 K-4)
Pr: Prandtl number
Sc_CO2: Schmidt number for CO2
Le067: Lewis number for water vapor to the power of 0.67
Kelvin: Conversion degree Celsius to Kelvin
DwDc: Ratio of the molecular diffusivities for water vapor and CO2
days2seconds: Seconds per day
kPa2Pa: Conversion kilopascal (kPa) to pascal (Pa)
Pa2kPa: Conversion pascal (Pa) to kilopascal (kPa)
umol2mol: Conversion micromole (umol) to mole (mol)
mol2umol: Conversion mole (mol) to micromole (umol)
kg2g: Conversion kilogram (kg) to gram (g)
g2kg: Conversion gram (g) to kilogram (kg)
kJ2J: Conversion kilojoule (kJ) to joule (J)
J2kJ: Conversion joule (J) to kilojoule (kJ)
se_median: Conversion standard error (SE) of the mean to SE of the median
frac2percent: Conversion between fraction and percent

Details

This function is passed as an argument to every function that uses one or more constants. Individual constants passed to a function can be easily altered. E.g. the following command will change the value of the von Karman constant from 0.41 to 0.4:

bigleaf.constants(k=0.4)

the value of a constant can be returned by calling:

bigleaf.constants()$*name_of_constant*

To permanently change the constants contained within this function (which makes sense for some of them, e.g. for the von Karman constant), the command fixInNamespace can be used. E.g.

fixInNamespace(bigleaf.constants,ns="bigleaf")

Note that this has to be repeated every time the package is newly installed/loaded.