S_r: longwave re-radiation (W / m^2)

S_r: longwave re-radiation (W / m^2)

.get_Sr(T_leaf, pars)

Arguments

T_leaf	Leaf temperature in Kelvin
pars	Concatenated parameters (leaf_par, enviro_par, and constants)

Value

Value in W / m\(^2\) of class units

Details

$$S_\mathrm{r} = 2 \sigma \alpha_\mathrm{l} T_\mathrm{air} ^ 4$$

The factor of 2 accounts for re-radiation from both leaf surfaces (Foster and Smith 1986).

Symbol	R	Description	Units	Default
\(\alpha_\mathrm{l}\)	abs_l	absorbtivity of longwave radiation (4 - 80 \(\mu\)m)	none	0.97
\(T_\mathrm{air}\)	T_air	air temperature	K	298.15
\(\sigma\)	s	Stephan-Boltzmann constant	W / (m\(^2\) K\(^4\))	5.67e-08

Note that leaf absorbtivity is the same value as leaf emissivity

References

Foster JR, Smith WK. 1986. Influence of stomatal distribution on transpiration in low-wind environments. Plant, Cell \& Environment 9: 751-9.

Examples

library(tealeaves)

cs <- make_constants()
ep <- make_enviropar()
lp <- make_leafpar()

T_leaf <- set_units(298.15, K)

tealeaves:::.get_Sr(T_leaf, c(cs, ep, lp))
#> 869.2087 [W/m^2]