bigleaf.constants {bigleaf} | R Documentation |

## 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*version 0.8.2 Index]