anisotropy in scattering

[Edward Hyer]

Hello Py6S wizards, 

I wished to set up a test to evaluate the extent to which 6S simulations were isotropic or anisotropic in the Rayleigh and aerosol scattering terms. I set it up this way:

s.ground_reflectance = GroundReflectance.HomogeneousRoujean(0.037, 0.0, 0.133)
s.aero_profile = AeroProfile.PredefinedType(AeroProfile.Desert)
s.geometry.solar_z = 30
s.geometry.solar_a = 0
data = SixSHelpers.Angles.run360(s, 'view', output_name='optical_depth_total')

But the 6S output appears to be uniform across all angles. I confirmed that I get different answers with a different input to AeroProfile.PredefinedType(), so the aerosol is included, but both the Mie and Rayleigh scattering results are uniform.

Am I just misunderstanding 6S-- does 6S simulate anisotropy only in the surface, and treat the atmosphere constituents as isotropic scatterers?

I apologize that this is probably not a Py6S question, but I'm posting it here just in case it is.

--Edward H.