leaftemp: Calculates leaf temperature of canopy layers

In ilyamaclean/microclimc: Below or above canopy microclimate modelling with R

Calculates leaf temperature of canopy layers

Description

Calculates leaf temperature from radiation fluxes and reference air and ground tempertaure

Usage

leaftemp(
  tair,
  relhum,
  pk,
  timestep,
  gt,
  gha,
  gv,
  Rabs,
  previn,
  vegp,
  soilp,
  theta,
  zlafact = 1,
  surfwet = 1
)

Arguments

tair	air temperature at two metres above canopy (deg C)
relhum	relative humidity at two metres above canopy (Percentage)
pk	air pressure at two metres above canopy (kPa)
timestep	duration of time step (s)
gt	heat conductance by turbulent convection (mol / m^2 / s)
gha	leaf-air heat conductance (mol / m^2 / s)
gv	leaf-air vapour conductance (mol / m^2 / s)
Rabs	Flux density of absorbed radiation as returned by leafabs() (W/m2)
previn	list of values from previous timestep
vegp	list of vegetation paramaters (see e.g. vegparams dataset)
soilp	list Soil paramaters (see e.g. soilparams dataset)
theta	volumetric soil moisture fraction of top soil layer (m^3 / m^3)
zlafact	numeric value indicating how close to leaves air temperatures are needed for (1 - average leaf-air distance, 0.5 = half average leaf-air distance etc.). Must be greater than 1.
surfwet	Fraction of surface area acting like a free‐water surface

Details

leaftemp computes the average leaf and air temperature of each canopy layer based on radiation and evaorative fluxes and reference air and ground temperature. The function automatically determines whether heat storage should be considered, based the specific heat capacity of the vegetation layer and the time step of the model.

Value

a list with the following elements:

tn air temperature of each layer (deg C)

tleaf leaf temperature of each layer (deg C)

ea vapour pressure (kPa)

gtt heat conductance to reference height two m above canopy

Rem emitted radiation (W / m^2)

H Sensible heat flux from leaf to air (W / m^2)

L Latent heat of vapourisation from leaf to air (W / m^2)

Examples

# Generate paramaters for function:
tme <- as.POSIXlt(0, origin = "2020-05-04 12:00", tz = "GMT")
previn <- paraminit(20, 10, 10, 15, 2, 80, 11, 500)
vegp <- microctools::habitatvars(3, 50, -5, tme, m = 20)
soilp <- soilinit("Loam")
z<-c((1:20) - 0.5) / 20 * vegp$hgt
# run function (setting conductances in current time step to same as in previous):
ltemp <- leaftemp(11, 80, 101.3, 60, previn$gt, previn$gha, previn$gv, previn$Rabs, previn,
                  vegp, soilp, 0.3)
plot(z ~ ltemp$tleaf, type = "l", xlab = "Leaf temperature", ylab = "Height")

ilyamaclean/microclimc documentation built on July 28, 2023, 1:40 a.m.