Uncollided transmission at lower boundary level
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 transmitted down to the level of the background (at z = ∼ 0) without undergoing any collisions within the canopy volume that it traverses. ftran_uc does not include contributions from isotropically diffuse illumination sources (should they be prescribed in the illumination conditions of a given RAMI experiment). ftran_uc is thus the magnitude of the un-collided direct-only radiation impinging on the background surface normalised by the magnitude of the incident direct-only radiation at the top of the canopy (entering through the reference area).
ftran_uc = transmission due to direct or isoptropic incident radiation that has no scattering interactions with the canopy.
|standard deviation of ftran_uc estimate*||%.6f|
*: if available, otherwise set to −1.000000.