Collided by canopy only transmission at lower boundary level for direct illumination only
This is the fraction of the incident direct radiation - passing through a planar reference surface of specified lateral dimension and elevation above the target, and oriented perpendicular to the underlying surface normal - that is intercepted by the canopy and scattered downward to the level of the background at z = ∼ 0. Radiation that is reflected back up from background surface before being intercepted by the canopy and scattered back down to the background again is thus counted only once (this is known as a black soil scenario). ftran_coco_dir does not include contributions from isotropic-diffuse illumination sources (should they be prescribed in the illumination conditions of a given RAMI experiment).
ftran_coco_dir = transmission due to direct incident radiation that has one or more scattering interactions with the canopy only.
|standard deviation of ftran_coco_dir estimate*||%.6f|
*: if available, otherwise set to −1.000000.