HR: 0800h
AN: P11B-0537 [Abstracts]
TI: Radar backscattering by densely packed particulate surfaces: first exact theoretical results
AU: * Mishchenko, M I
EM: crmim@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United
States
AU: Liu, L
EM: lliu@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United
States
AB:
Analyses of radar backscattering by densely packed particulate surfaces based on direct solutions of the Maxwell
equations are virtually absent. This makes uncertain the correctness of conclusions derived on the basis of the
conventional theories of radiative transfer and coherent backscattering applicable to sparsely distributed
scatterers. To address this fundamental problem, we use the numerically exact superposition T-matrix method
and perform extensive computations of electromagnetic scattering by a 3D volume filled with randomly distributed
wavelength-sized particles. These computations are used to simulate and analyze the effect of randomness of
particle positions as well as the onset and evolution of various multiple-scattering effects with increasing number
of particles. Our exact results illustrate and substantiate the methodology underlying the microphysical theories
of radiative transfer and coherent backscattering. Furthermore, we show that even in densely packed media,
electromagnetic waves multiply scattered along strings of widely separated particles still provide a significant
contribution to the total scattered signal and thereby make quite pronounced the classical radiative transfer and
coherent backscattering effects. The model results are consistent with the values of the linear and circular
polarization ratios observed for various ice-covered planetary surfaces.
DE: 0619 Electromagnetic theory
DE: 0659 Random media and rough surfaces
DE: 0669 Scattering and diffraction
DE: 0689 Wave propagation (2487, 3285, 4275, 4455, 6934)
DE: 5464 Remote sensing
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting