loctrans

Description

This is the total transmission through the canopy (direct and diffuse radiation) that reaches a series of adjacent reference areas located at height z_ref, each one with specified X,Y dimensions and locations. For example, assuming that the reference height is equal to the bottom of the canopy, that is, z_ref = z₀, then the local transmission for some reference patch centered at XC,YC is obtained from the ratio of the radiation that is incident at the soil I(z₀) (but within the spatial confines of the reference area centered at XC,YC) and the radiation incident at the top of the canopy (z = z_max), passing through a likewise shaped reference area of identical dimensions and centered at the same x,y location.

T(XC,YC,z₀) = I>(XC,YC,z₀) ⁄ I>(XC,YC,z_max)

Output file format

Header

Header line content	Header line format
# rows in file (# of reference areas in transect)	%4d
# columns in file	%4d
X-dimension of reference area	%.6f
Y-dimension of reference area	%.6f

Columns content

Body lines content	Body lines format
XC	%.6f
YC	%.6f
ZC	%.6f
loctrans	%.6f

*: if available, otherwise set to −1.000000.

where:

• XC: X coordinate of center of reference area patch;
• YC: Y coordinate of center of reference area patch;
• ZC: Z coordinate of center of reference area patch;
• loctrans: ratio of incident radiation at z = 0 divided by that at z = z_max (passing through dimensions of reference area patch)

Example output

Transect along the X-axis composed of 21 patches of 1×1 m² surface area followed by a transect along the Y-axis also composed of 21 patches of 1×1 m² surface area.

42 4 1.000000 1.000000
     -10.000000     0.000000      0.000000     0.668422
     -9.000000      0.000000      0.000000     0.192887
     -8.000000      0.000000      0.000000     0.068017
     -7.000000      0.000000      0.000000     0.122837
     -6.000000      0.000000      0.000000     0.284787
     -5.000000      0.000000      0.000000     0.172861
     -4.000000      0.000000      0.000000     0.107715
     -3.000000      0.000000      0.000000     0.897916
     -2.000000      0.000000      0.000000     0.342299
     -1.000000      0.000000      0.000000     0.415999
      0.000000      0.000000      0.000000     0.415999
      1.000000      0.000000      0.000000     0.415999
      2.000000      0.000000      0.000000     0.342299
      3.000000      0.000000      0.000000     0.897916
      4.000000      0.000000      0.000000     0.107715
      5.000000      0.000000      0.000000     0.172861
      6.000000      0.000000      0.000000     0.284787
      7.000000      0.000000      0.000000     0.122837
      8.000000      0.000000      0.000000     0.068017
      9.000000      0.000000      0.000000     0.192887
      10.000000     0.000000      0.000000     0.668422
      0.000000     -10.000000     0.000000     0.668422
      0.000000     -9.000000      0.000000     0.192887
      0.000000     -8.000000      0.000000     0.068017
      0.000000     -7.000000      0.000000     0.122837
      0.000000     -6.000000      0.000000     0.284787
      0.000000     -5.000000      0.000000     0.172861
      0.000000     -4.000000      0.000000     0.107715
      0.000000     -3.000000      0.000000     0.897916
      0.000000     -2.000000      0.000000     0.342299
      0.000000     -1.000000      0.000000     0.415999
      0.000000      0.000000      0.000000     0.415999
      0.000000      1.000000      0.000000     0.415999
      0.000000      2.000000      0.000000     0.342299
      0.000000      3.000000      0.000000     0.897916
      0.000000      4.000000      0.000000     0.107715
      0.000000      5.000000      0.000000     0.172861
      0.000000      6.000000      0.000000     0.284787
      0.000000      7.000000      0.000000     0.122837
      0.000000      8.000000      0.000000     0.068017
      0.000000      9.000000      0.000000     0.192887
      0.000000      10.000000     0.000000     0.668422