bigleaf.constants: Constants Used in the bigleaf Package

In bigleaf: Physical and Physiological Ecosystem Properties from Eddy Covariance Data

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.

bigleaf documentation built on Aug. 22, 2022, 9:09 a.m.