Light Scattering by Irregularly Shaped Particles - Schuerman

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Résumé :
This volume contains most of the invited papers presented at the International Workshop on Light Scattering by Irregularly Shaped Particles held on June 5-7, 1979. at the State University of New York at Albany (SUNYA). Over seventy participants representing many dis? ciplines convened to define some of the ever-increasing number of resonant light-scattering problems associated with particle shape and to relate their most recent investigations in this field. It is obvious from the two introductory papers that an investi? gator's primary discipline determines his/her approach to the light? scattering problem. The meteorologist, Diran Deirmendjian, advocates an empirical methodology: to model the scattering by atmospheric aerosols, using equivalent spheres as standards, in the most effi? cient and simplest manner that is consistent with remote sensing, in situ, and laboratory? data. Because of the almost infinite variety of particle shapes, he questions not only the possibility but even the usefulness of the exact solution of scattering by a totally arbitrary particle. The astrophysicist, J. Mayo Greenberg, is primarily concerned with the information content carried by the scattered light because this radiation is the sole clue to under? standing the nature of interstellar dust. What measurements (polar? ization, color dependence, etc ??? ) should be made to best determine a given particle characteristic (size, surface roughness, refractive index, etc ??? )? Thus, he considers the physics of the scattering process to be of paramount interest.

Sommaire:
1: Introduction.- Some Remarks on Science, Scientists, and the Remote Sensing of Particulates.- Focusing in on Particle Shape.- 2: User Needs.- Sensing Ice Clouds from Satellites.- Lidar Visibility Measurements.- Non-Spherical Particle Scattering: Air Force Applications.- Particles Producing Strong Extinction in the Infrared.- 3: Specific Particle Descriptions.- Shape of Raindrops.- Atmospheric Ice Crystals.- Physical Properties of Atmospheric Particulates.- Some Characteristics of the Antarctic Aerosol.- Examples of Realistic Aerosol Particles Collected in a Cascade Impactor.- 4: Theoretical Methods.- Absorption by Small Regular Non-Spherical Particles in the Rayleigh Region.- Infrared Absorption Spectra of Non-Spherical Particles Treated in the Rayleigh-Ellipsoid Approximation.- Scattering by Non-Spherical Particles of Size Comparable to a Wavelength: A New Semi-Empirical Theory.- Scattering and Absorption by Wavelength Size Discs.- Perturbation Approach to Light Scattering by Non-Spherical Particles.- Exact Calculations of Scattering from Moderately-Nonspherical Tn-Particles: Comparisons with Equivalent Spheres.- Surface Waves in Light Scattering by Spherical and Non-Spherical Particles.- Shifrin's Method Applied to Scattering by Tenuous Non-Spherical Particles.- Energy Conservation: A Test for Scattering Approximations.- Electromagnetic Scattering from Two Identical Pseudospheres.- Absorption by Particle Edges and Asperities.- On the Scattering from Arbitrarily Shaped Inhomogeneous Particles - Exact Solution.- Light Scattering by Hexagonal Columns and Plates.- Scattering of Radiation by a Large Particle with a Rough Surface.- 5: Experimental Methods.- The Microwave Analog Facility at SUNYA: Capabilities and Current Programs.- Observation of Light Scattering from Oriented Non-Spherical Particles Using Optical Levitation.- The Effect of an Electric Field on the Backscattered Radiance of a Single Water Droplet.- In-Situ Light Scattering Techniques for Determining Aerosol Size Distributions and Optical Constants.- Problems in Calibrating a Polar Nephelometer.- 6: Experimental Results.- Extinction Signatures of Non-Spherical/Non-Isotropic Particles.- Scattering by Particles of Non-Spherical Shape.- Phase Matrix Measurements for Electromagnetic Scattering by Sphere Aggregates.- Reflectivity of Single Micron Size Irregularly Shaped Dust Grains.- Biological Particles as Irregularly Shaped Scatterers.- 7: Inversion and Information Content.- Inference of Scatterer Size Distribution from Single Scattering Matrix Data.- Light Scattering by Irregularly Shaped Particles Versus Spheres: What Are Some of the Problems Presented in Remote Sensing of Atmospheric Aerosols?.- Participants.