Radiative Transfer

BeerLambertParameters{FT <: AbstractFloat}

The required parameters for the Beer-Lambert radiative transfer model.

• ld: Leaf angle distribution function (unitless)

• α_PAR_leaf: PAR leaf reflectance (unitless)

• α_NIR_leaf: NIR leaf reflectance

• Ω: Clumping index following Braghiere (2021) (unitless)

• λ_γ_PAR: Typical wavelength per PAR photon (m)

• λ_γ_NIR: Typical wavelength per NIR photon (m)

compute_absorbances(
    RT::BeerLambertModel{FT},
    PAR,
    NIR,
    LAI,
    K,
    _,
    _,
    _,
    _,
)

Computes the APAR and ANIR absorbances for a canopy in the case of the Beer-Lambert model. The absorbances are a function of the radiative transfer model, as well as the magnitude of incident PAR and NIR radiation in moles of photons, the leaf area index, and the extinction coefficient. Returns a tuple of (APAR, ANIR).

compute_absorbances(
    RT::TwoStreamModel{FT},
    PAR,
    NIR,
    LAI,
    K,
    θs,
    α_soil_PAR,
    α_soil_NIR,
    frac_diff,
)

Compute APAR and ANIR absorbances for a canopy in the case of the two-stream model. The absorbances are a function of the radiative transfer model, as well as the magnitude of incident PAR and NIR radiation in moles of photons, the leaf areaindex, the extinction coefficient, the solar zenith angle, and soil albedo. Returns a tuple of (APAR, ANIR).

plant_absorbed_pfd(
    RT::BeerLambertModel{FT},
    SW_IN:FT,
    α_leaf::FT,
    LAI::FT,
    K::FT,
)

Computes the absorbed photon flux density in terms of mol photons per m^2 per second for a radiation band. If the reflectance and radiation for NIR is passed, computes ANIR and if PAR reflectance and rediation are passed, computes APAR.

This applies the Beer-Lambert law, which is a function of incident radiation (SW_IN; moles of photons/m^2/), leaf reflectance (α_PAR_leaf), the extinction coefficient (K), leaf area index (LAI), and the clumping index (Ω). The function takes in all parameters in the parameters struct for a BeerLambertModel, along with the SW_IN, LAI, extinction coefficient K, and solar zenith angle.

plant_absorbed_pfd(
    RT::TwoStreamModel{FT},
    α_leaf,
    SW_IN::FT,
    LAI::FT,
    K::FT,
    τ_leaf,
    θs::FT,
    α_soil::FT,
)

Computes the absorbed photon flux density in terms of mol photons per m^2 per second for a radiation band. If the reflectance, radiation, transmittance, and soil albedo for NIR is passed, computes ANIR and if PAR reflectance, rediation, transmittance, and soil albedo are passed, computes APAR.

This applies the two-stream radiative transfer solution which takes into account the impacts of scattering within the canopy. The function takes in all parameters from the parameter struct of a TwoStreamModel, along with the incident radiation, LAI, extinction coefficient K, soil albedo from the canopy soil_driver, and solar zenith angle.

extinction_coeff(ld::FT,
                 θs::FT) where {FT}

Computes the vegetation extinction coefficient (K), as a function of the sun zenith angle (θs), and the leaf angle distribution (ld).