dot-get_Rabs.RdR_abs: total absorbed radiation (W / m^2)
.get_Rabs(pars, unitless)Concatenated parameters (leaf_par, enviro_par, and constants)
Logical. Should function use parameters with units? The function is faster when FALSE, but input must be in correct units or else results will be incorrect without any warning.
Value in W / m\(^2\) of class units
The following treatment follows Okajima et al. (2012):
$$R_\mathrm{abs} = \alpha_\mathrm{s} (1 + r) S_\mathrm{sw} + \alpha_\mathrm{l} \sigma (T_\mathrm{sky} ^ 4 + T_\mathrm{air} ^ 4)$$
The incident longwave (aka thermal infrared) radiation is modeled from sky and air temperature \(\sigma (T_\mathrm{sky} ^ 4 + T_\mathrm{air} ^ 4)\) where \(T_\mathrm{sky}\) is function of the air temperature and incoming solar shortwave radiation:
$$T_\mathrm{sky} = T_\mathrm{air} - 20 S_\mathrm{sw} / 1000$$
| Symbol | R | Description | Units | Default |
| \(\alpha_\mathrm{s}\) | abs_s | absorbtivity of shortwave radiation (0.3 - 4 \(\mu\)m) | none | 0.80 |
| \(\alpha_\mathrm{l}\) | abs_l | absorbtivity of longwave radiation (4 - 80 \(\mu\)m) | none | 0.97 |
| \(r\) | r | reflectance for shortwave irradiance (albedo) | none | 0.2 |
| \(\sigma\) | s | Stefan-Boltzmann constant | W / (m\(^2\) K\(^4\)) | 5.67e-08 |
| \(S_\mathrm{sw}\) | S_sw | incident short-wave (solar) radiation flux density | W / m\(^2\) | 1000 |
| \(S_\mathrm{lw}\) | S_lw | incident long-wave radiation flux density | W / m\(^2\) | calculated |
| \(T_\mathrm{air}\) | T_air | air temperature | K | 298.15 |
| \(T_\mathrm{sky}\) | T_sky | sky temperature | K | calculated |
Okajima Y, H Taneda, K Noguchi, I Terashima. 2012. Optimum leaf size predicted by a novel leaf energy balance model incorporating dependencies of photosynthesis on light and temperature. Ecological Research 27: 333-46.
library(tealeaves)
cs <- make_constants()
ep <- make_enviropar()
lp <- make_leafpar()
ep$T_sky <- ep$T_sky(ep)
tealeaves:::.get_Rabs(c(cs, ep, lp), FALSE)
#> 1363.813 [W/m^2]