Skip to content

Group canopy_radiation

Modules > canopy_radiation

Radiation attenuation and PPFD calculations within canopy.

Public Functions

Type Name
subroutine canopy_rad_mod::canopy_fsun_clu (FCLAI FCLAI, LAI LAI, CLU CLU, COSZEN COSZEN, FSUN FSUN)
Calculate sunlit fraction using clumping index.
subroutine canopy_rad_mod::canopy_ppfd_exp (ZK ZK, FCH FCH, SFCRAD SFCRAD, LAI LAI, FSUN FSUN, PPFD_SUN PPFD_SUN, PPFD_SHADE PPFD_SHADE, PPFD_AVE PPFD_AVE)
Calculate PPFD profiles using exponential model.

Public Functions Documentation

function canopy_fsun_clu

Calculate sunlit fraction using clumping index. 

subroutine canopy_rad_mod::canopy_fsun_clu (
    FCLAI FCLAI,
    LAI LAI,
    CLU CLU,
    COSZEN COSZEN,
    FSUN FSUN
)

Computes sunlit/shaded fraction through canopy using photolysis correction factor and clumping index

Parameters:

  • FCLAI Fractional cumulative LAI profile (dimensionless)
  • LAI Model input total Leaf Area Index (m²/m²)
  • CLU Model input Clumping Index (dimensionless)
  • COSZEN Model input Cosine Solar Zenith Angle (dimensionless)
  • FSUN Sunlit/Shaded fraction from photolysis correction factor

Author:

P. C. Campbell

Date:

Jun 2023

Note:

Based on Bonan (2019) equation 14.18 for clumping correction

function canopy_ppfd_exp

Calculate PPFD profiles using exponential model. 

subroutine canopy_rad_mod::canopy_ppfd_exp (
    ZK ZK,
    FCH FCH,
    SFCRAD SFCRAD,
    LAI LAI,
    FSUN FSUN,
    PPFD_SUN PPFD_SUN,
    PPFD_SHADE PPFD_SHADE,
    PPFD_AVE PPFD_AVE
)

Computes photosynthetic photon flux density for sunlit and shaded leaves through canopy using exponential decay models from Silva et al. (2020)

Parameters:

  • ZK Input model heights (m)
  • FCH Model input canopy height (m)
  • SFCRAD Model input instantaneous surface downward shortwave flux (W/m²)
  • LAI Model input total Leaf Area Index (m²/m²)
  • FSUN Sunlit/Shaded fraction from photolysis correction factor
  • PPFD_SUN PPFD for sunlit leaves (μmol photons/m²/s)
  • PPFD_SHADE PPFD for shaded leaves (μmol photons/m²/s)
  • PPFD_AVE Average PPFD for sunlit and shaded leaves (μmol photons/m²/s)

Author:

P. C. Campbell

Date:

Jun 2023

Note:

Based on Silva et al. (2020) 5-layer canopy exponential PPFD model Silva, S. J., Heald, C. L., and Guenther, A. B. (2020). Development of a reduced-complexity plant canopy physics surrogate model for use in chemical transport models: a case study with GEOS-Chem v12.3.0. Geoscientific Model Development, 13, 2569-2585. https://doi.org/10.5194/gmd-13-2569-2020