Delta-T Devices SunScan SS1 User Manual page 37

Advice on Absorption and ELADP values
Absorption
Absorption is the percentage of incident PAR absorbed by the leaf.
Most leaves have Absorption values in the range 0.8 - 0.9, so the default
value of 0.85 will usually be appropriate.
Only adjust the Absorption value if you have good reason to,
e.g. if working with very thick, dark leaves, or very thin transparent ones.
If you set the Absorption value to 1.0, the LAI calculations will be
equivalent to simpler models that assume completely black leaves.
ELADP
ELADP is the Ellipsoidal Leaf Angle Distribution Parameter.
The ELADP is a way of characterising the horizontal or vertical tendency
of leaves in a canopy.
The canopy leaf elements are
assumed to be distributed in
space in the same directions
and proportions as the surface
area of an ellipsoid of
revolution, symmetrical about
the vertical axis. The Leaf
Angle Distribution can then be
described by a single
parameter, the ratio of the
Horizontal to Vertical axes of
the Ellipsoid.
ELADP
This is also equal to the ratio of the vertically projected area to the
horizontally projected area of the ellipsoid (or of the canopy elements).

An ELADP of 1.0 gives a spherical Leaf Angle Distribution, where all
leaf angles are equally represented.

A high ELADP (e.g. 1024) represents a broad flat ellipsoid, i.e. the
leaf elements are all horizontal

A low ELADP (0.0) represents a tall thin ellipsoid, i.e. all the leaf
elements are vertical.
SS1 User Manual v3.3
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H V
Most crops have ELADPs in the range 0.5 - 2.0.
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What to Measure and How  37