Abstract
In this paper, we study the behavior of the scattering efficiency Qsca, the absorption efficiency Qabs, the single-scattering albedo ω, the asymmetry factor g, and the backscattered fraction for isotropically incident radiation for randomly oriented rotationally symmetric nonspherical particles of radii r = r0[1 + ∊Tn(cosθs)], where Tn is a Chebyshev polynomial of order n. By taking n = 2,3,4,6,8, and 20, and ∊ = −0. 2 to 0.2 in steps of 0.05, twenty-three different shapes have been considered for these Chebyshev particles. The scattering calculations have been carried out using the Extended Boundary Conditions Method for individual particles with refractive index in the equal-volume-sphere size parameter range 1 ≤ x ≤ 25. Unshape-averaged and shape-averaged nonspherical single-scattering quantities have then been compared to corresponding size-averaged (over Δx = 0.1x) spherical results. It is shown that nonsphericity always increases Qabs for size parameters larger than ∼10, while it decreases g—and correspondingly increases —in the size range 8 ≤ x ≤ 15. Qsca seems to be on the average somewhat larger for nonspherical particles, while ω tends to be smaller. Concavity almost always enhances the spherical–nonspherical differences.
© 1986 Optical Society of America
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