MATLAB
`sigI2 = SphericalIrradianceVariance(alpha,lambda,Geom,Atm)`

Computes the spherical wave normalized irradiance variance given turbulence assumptions, propagation geometry, and wavelength. Returns NaN if propagation path intersects earth surface. Propagation is from platform to the target and this function returns the target plane variance. Accounts for strong turbulence conditions.

 Parameters Description alpha [vector] Multiplier on turbulence model lambda [scalar] Wavelength of laser (m) Geom [struct/list] Geometry parameters. Can be a structure from GeomStruct or a comma separated list of (...,hp,ht,rd) - not required if Atm is a structure from AtmStruct hp [scalar] Altitude of transmit/receive platform (m) ht [scalar] Altitude of target (m) rd [scalar] Downrange of target along spherical earth surface (m) Atm [struct/string] Atmospheric modeling parameters. Can be a structure from AtmStruct or a turbulence profile model to be used.
 Return Values Description sigI2 [vector] Spherical wave normalized irradiance variance

• L. C. Andrews and R. L. Phillips, Laser Beam Propagation through Random Media, 2nd ed. Bellingham, Wash.: SPIE Press, 2005.

>> sigI2 = SphericalIrradianceVariance(1.0,1.0e-6,AtmStruct)

>> sigI2 = SphericalIrradianceVariance(1.0,1.0e-6,GeomStruct,AtmStruct)

• Geom and Atm must have same values for hp, ht, and rd.
>> sigI2 = SphericalIrradianceVariance(1.0,1.0e-6,GeomStruct,'HV57')

>> sigI2 = SphericalIrradianceVariance(1.0,1.0e-6,10,3000,10000,'HV57')

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