fetch3.nhl_transpiration.NHL_functions.calc_rad_attenuation#

calc_rad_attenuation(PAR, LAD, dz, Cf=0.85, x=1, **kwargs)#

Calculates the vertical attenuation of radiation through the canopy

Parameters:

  • PAR (float) – photosynthetically active radiation at canopy top [µmol m-2 s-1]

  • LAD (array) – Leaf area density [m2leaf m-2crown m-1stem] at each height in z

  • dz (float) – Vertical discretization interval [m]

  • Cf (float) – Clumping fraction [unitless]. By default assumed to be 0.85 (Forseth & Norman 1993)

  • x (float) – Ratio of horizontal to vertical projections of leaves (leaf angle distribution). By default assumed to be spherical (x=1).

  • calc_zenith_angle (**kwargs to be passed to) –

Returns:

  • P0 (array) – attenuation fraction of PAR penetrating the canopy at each level z [unitless]

  • Qp (array) – absorbed photosynthetically active radiation at each level within the canopy [µmol m-2 s-1]