biophysics: Physical and biophysical utility functions

Description

Internal utility functions for the calculation of biophysical variables.

Usage

biophysics_radiationDiurnalPattern(t, daylength)
biophysics_temperatureDiurnalPattern(
  t,
  tmin,
  tmax,
  tminPrev,
  tmaxPrev,
  tminNext,
  daylength
)
biophysics_leafTemperature(absRad, airTemperature, u, E, leafWidth = 1)
biophysics_leafTemperature2(
  SWRabs,
  LWRnet,
  airTemperature,
  u,
  E,
  leafWidth = 1
)
biophysics_leafVapourPressure(leafTemp, leafPsi)
biophysics_irradianceToPhotonFlux(I, lambda = 546.6507)
biophysics_waterDynamicViscosity(temp)

Value

Values returned for each function are:

biophysics_leafTemperature and biophysics_leafTemperature2: leaf temperature (in ºC)
biophysics_leafVapourPressure: leaf vapour pressure (in kPa)
biophysics_radiationDiurnalPattern: the proportion of daily radiation corresponding to the input time in seconds after sunrise.
biophysics_temperatureDiurnalPattern: diurnal pattern of temperature.
biophysics_waterDynamicViscosity: Water dynamic viscosity relative to 20ºC.

Arguments

t: Time of the day (in seconds).
daylength: Day length (in seconds).
tmin, tmax: Minimum and maximum daily temperature (ºC).
tminPrev, tmaxPrev, tminNext: Maximum and minimum daily temperatures of the previous and following day (ºC).
absRad: Absorbed long- and short-wave radiation (in W·m-2).
airTemperature: Air temperature (in ºC).
u: Wind speed above the leaf boundary layer (in m/s).
E: Transpiration flow (in mmol H20·m-2·s-1) per one sided leaf area basis.
leafWidth: Leaf width (in cm).
SWRabs: Absorbed short-wave radiation (in W·m-2).
LWRnet: Net long-wave radiation balance (in W·m-2).
leafTemp: Leaf temperature (ºC).
leafPsi: Leaf water potential (MPa).
I: Irradiance (in W*m-2).
lambda: Wavelength (in nm).
temp: Temperature (ºC).

Author

Miquel De Cáceres Ainsa, CREAF

Details

Functions biophysics_leafTemperature and biophysics_leafTemperature2 calculate leaf temperature according to energy balance equation given in Campbell and Norman (1988).

Function biophysics_radiationDiurnalPattern follows the equations given in Liu and Jordan (1960).

Function biophysics_temperatureDiurnalPattern determines diurnal temperature pattern assuming a sinusoidal pattern with T = Tmin at sunrise and T = (Tmin+Tmax)/2 at sunset and a linear change in temperature between sunset and Tmin of the day after (McMurtrie et al. 1990).

Function biophysics_waterDynamicViscosity calculates water dynamic viscosity following the Vogel (1921) equation.

References

Campbell, G. S., and J. M. Norman. 1998. An introduction to environmental biophysics: 2nd edition. (eqns. 14.1 & 14.3)

B. Y. H. Liu and R. C. Jordan, “The interrelationship and characteristic distribution of direct, diffuse and total solar radiation,” Solar Energy, vol. 4, no. 3, pp. 1–19, 1960.

McMurtrie, R. E., D. A. Rook, and F. M. Kelliher. 1990. Modelling the yield of Pinus radiata on a site limited by water and nitrogen. Forest Ecology and Management 30:381–413.

H. Vogel, "Das Temperaturabhangigkeitsgesetz der Viskositat von Flussigkeiten", Physikalische Zeitschrift, vol. 22, pp. 645–646, 1921.