Multiple scattering from Chebyshev particles: Monte Carlo simulations for backscattering in lidar geometry

Year: 1996

Authors: Mannoni A., Flesia C., Bruscaglioni P., Ismaelli A.

Autors Affiliation: Istituto Nazionale di Ottica, Largo E.Fermi 6, 50125 Firenze, Italy;
Groupe de Physique Appliquee, University of Geneva, 20 Rue de l’Ecole de Medecine, 1211 Geneve 4, Switzerland;
Dipartimento di Fisica, University of Florence, Via S. Marta 3, 50139 Firenze, Italy

Abstract: Lidar measurements are often interpreted on the basis of two fundamental assumptions: absence of multiple scattering and sphericity of the particles that make up the diffusing medium. There are situations in which neither holds true. We focus our interest on multiply-scattered returns from homogeneous layers of monodisperse, randomly oriented, axisymmetric nonspherical particles. T2 Chebyshev particles have been chosen and their single-scattering properties have been reviewed. A Monte Carlo procedure has been employed to calculate the backscattered signal for several fields of view. Comparisons with the case of scattering from equivalent ~equal-volume! spheres have been carried out ~narrow polydispersions have been used to smooth the phase functions’ oscillations!. Our numerical effort highlights a considerable variability in the intensity of the multiply-scattered signal, which is a consequence of the strong dependence of the backscattering cross section on deformation of the particles. Even more striking effects have been noted for depolarization; peculiar behavior was observed at moderate optical depths when particles characterized by a large backscattering depolarization ratio were employed in our simulations. The sensitivity of depolarization to even small departures from sphericity, in spite of random orientation of the particles, has been confirmed. The results obtained with the Monte Carlo codes have been successfully checked with an analytical formula for double scattering.

Journal/Review: APPLIED OPTICS

Volume: 35 (36)      Pages from: 7151  to: 7164

KeyWords: nonspherical particles; multiple scattering; depolarization
DOI: 10.1364/AO.35.007151

Citations: 10
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