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ABSTRACT: The intensity and polarization of light scattered from marine aerosols affect visibility and contrast in the marine atmospheric boundary layer (MABL). The polarization properties of scattered light in the MABL vary with size, refractive index, number distributions, and environmental conditions. Laboratory measurements were used to determine the characteristics and variability of the polarization of light scattered by aerosols similar to those in the MABL. Scattering from laboratory-generated sea-salt-containing (SSC) [NaCl, (NH(4))(2) SO(4), and seawater] components of marine aerosols was measured with a scanning polarization-modulated nephelometer. Mie theory with Gaussian and log normal size distributions of spheres was used to calculate the polarized light scattering from various aerosol composition models and from experimentally determined distributions of aerosols in the marine boundary layer. The modeling was verified by comparison with scattering from distilled water aerosols. The study suggests that polarimetric techniques can be used to enhance techniques for improving visibility and remote imaging for various aerosol types, Sun angles, and viewing conditions.
Applied Optics 08/1997; 36(21):5168-84. · 1.41 Impact Factor
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ABSTRACT: The angle- and polarization-dependent light scattering were measured for oriented first-year and multiyear sea ice taken from the Chukchi Sea near Pt. Barrow, Alaska. The entire Mueller matrix for these samples was determined at 532 nm. Mueller matrices were also determined for artificially grown saline ice samples and melted samples of the respective ice types. Phase functions for thin-slab samples are qualitatively consistent with calculations for scattering from brine inclusions in a solid ice medium and depend strongly on the shape of the scattering sample. Small orientation-dependent effects are observed for scattering from oriented sea ice. A simple model is used to describe qualitatively some features of the measured sea ice Mueller matrices. This model combines the effects of scattering from spherical inhomogeneities and the intrinsic birefringence of pure water ice. A set of Mueller matrix inequalities is presented and used to obtain physical insight into the measurement results.
Applied Optics 03/1997; 36(6):1278-88. · 1.41 Impact Factor
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ABSTRACT: We have developed a novel bistatic polarization‐modulated nephelometer that probes a medium enabling in situ measurement of angle‐ and polarization‐dependent light scattering through a planar interface. This is particularly important for media with a planar interface such as sea ice but also for media in which measurements at great distance or depth, e.g., the atmosphere, are desirable. The instrument sits directly and noninvasively on the planar surface of the scattering medium. Light from a laser beam is directed into the medium and the scattered light is detected by analyzer optics. The angle of both the laser and detector beams in the medium can be varied continuously. Alternating current polarimetry is used to obtain phase function and polarization information of the scattered light. Measurements from this instrument of scattering from monodisperse polystyrene (latex) spheres in the laboratory are in good qualitative agreement with the results of Mie calculations and measurements made with a conventional monostatic nephelometer. This instrument has also been used to make preliminary investigations of scattering in sea ice in Pt. Barrow, Alaska. © 1996 American Institute of Physics.
Review of Scientific Instruments 07/1996; · 1.37 Impact Factor
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ABSTRACT: The coupled-dipole approximation has been used to model polarized light-scattering data obtained from the sperm of the octopus Eledone cirrhosa. Mueller scattering-matrix elements (which describe how a sample alters the intensity and degree of polarization of scattered light) were measured as a function of angle. The sample was modeled as a helical fiber believed to correspond to a DNA protein complex. It was necessary to propose an inherent anisotropy in the polarizability of the fiber in order to fit the data. The direction of the principle axes of the polarizability were determined by comparing the model with experimental data. The results suggest that the 2-nm DNA fibers are perpendicular to the thick fiber that defines the helical geometry of the octopus sperm head.
Applied Optics 08/1994; 33(24):5733-44. · 1.41 Impact Factor
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ABSTRACT: Striking light-scattering behavior was observed from a marine dinoflagellate, Prorocentrum micans. Measurements of the angular dependence of the 16 Mueller matrix elements were performed on single cells with a polarization-modulation nephelometer by using a new method for cell immobilization. First the dinoflagellate cells were immobilized in a transparent silica gel containing alcohol, and then a second liquid was diffused into the gel to match the index of refraction of the gel network, thereby producing a transparent support medium that scatters less than one tenth the amount of light scattered by a single cell at 90 degrees . Measurements of scattering by a single cell revealed that all 16 matrix elements were significantly nonzero and different from each other. All matrix elements have an extremely rich, reproducible structure that is highly dependent on cell orientation. The matrix elements symmetrically across the diagonal were not equivalent. Striking features of the measurements are the large peak values of S(13), S(14), and other off-diagonal block elements. We believe that this is the first report of such scattering signals by single, suspended marine microorganisms.
Applied Optics 05/1992; 31(15):2924-31. · 1.41 Impact Factor
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Limnology and Oceanography. 01/1989;
