Level 2 Help for PHO_HAPKE_86_HG1

Single-scattering albedo of the soil particles. It characterizes the efficiency of an average particle to scatter and absorb light. 
One of the classical Hapke parameter.

One of the classical Hapke parameter.
Parameter which characterizes the soil structure in the terms of porosity, particle-size distribution, and rate of compaction with depth (angular width of opposition surge due to shadowing). 

One of the classical Hapke parameter. 
Opposition magnitude coefficient. The total amplitude of the opposition surge due to shadowing. It is the ratio of the light scattered from near the illuminated surface of the particle to the total amount of light scattered at zero phase : 
B_SHOE=S(0)/(W_SOIL*p(0))
with p(0) - soil phase function
S(0) - opposition surge amplitude term which characterizes the contribution of 
light scattered from near the front surface of individual particles at zero 
phase.
For a true, shadow-hiding opposition effect, 0<=B_SHOE<=1.
However, there are several other phenomena that may also cause a surge in brightness at small phase angles. These including the following:
1) The coherent backscatter or weak photon localisation due to multiply 
   scattered light.
2) An single-particle opposition effect caused by complex porous agglomerates 
   ( soil phase function )
3) Glory caused by sperical particles ( soil phase function )
4) Internal reflections of transparent particles ( soil phase function )
   These various phenomena may be large enough to increase the opposition surge 
   by more than a factor of 2. This possibility may be taken into account by 
   allowing B_SHOE to be greater than 1.
 

Average topographic slope angle of surface roughness at subresolution scale.
One of the classical Hapke parameter. 

Parameter of the first term of the Henyey-Greenstein soil particle 
phase function.