computeG function

Compute the mean projection of unit leaf area on the plane perpendicular to beam direction, namely, G parameter.

computeG(LeafAngleZ, FractionZ, LeafAngleA, FractionA, theta, alpha)

Arguments

• LeafAngleZ: The center angles list of leaf zenith angle intervals.
• FractionZ: The leaf area fraction list given leaf zenith angle intervals list.
• LeafAngleA: The center angles list of leaf azimuth angle intervals.
• FractionA: The leaf area fraction list given leaf azimuth angle intervals list.
• theta: The zenith angle of beam direction.
• alpha: The azimuth angle of beam direction.

Returns

The mean projection of unit leaf area on the plane perpendicular to beam direction, namely, G value.

Examples

angleZ<-c(4.5, 13.5, 22.5, 31.5, 40.5, 49.5, 58.5, 67.5, 76.5, 85.5)
angleA<-c(10,30,50,70,90,110,130,150,170,190,210,230,250,270,290,310,330,350)
sADis<-sysAziDis()
sZDis<-sphericalDis()
for(solarZenith in 10:80)
{
  print(computeG(angleZ,sZDis,angleA,sADis,solarZenith,40))
}

References

Wang, W. M., Li, Z. L., & Su, H. B. (2007). Comparison of leaf angle distribution functions: effects on extinction coefficient and fraction of sunlit foliage. Agricultural and Forest Meteorology, 143(1), 106-122.

Author(s)

Wei-Min Wang (wmwang AT gmail.com)