George F. Beardsley

Mueller Scattering Matrix of Sea Water

The Mueller phase matrices of sea water were measured at scattering angles of 20°, 30°, ⋯ 130° for ocean water, coastal water, harbor water, and river water. The measurements were made with a modified Brice–Phoenix light-scattering photometer. The measured phase matrices exhibit strong forward scattering, and the polarization is comparable in form to that due to Rayleigh scatterers but reaches a maximum value in the range 40%–70%. The matrices are also strongly diagonal and approximate the theoretical Mie scattering matrices for spheres.

Theoretical Dependence of the Near-Asymptotic Apparent Optical Properties on the Inherent Optical Properties of Sea Water*

The apparent optical properties of sea water are a set of measurables that describe the geometry of the submarine light field. These properties are related to the inherent optical properties—the volume attenuation coefficient and the volume scattering function—through the process of radiative transfer. A numerical approximation to the equation of radiative transfer was programmed for solution on a high-speed digital computer. The technique is based on resolving the hydrosol into a system of thin slabs, finding approximate transmission and reflection operators for each slab, and then systematically applying these operators to determine the geometry of the light field in the interior of the system of slabs. Thus each set of calculations produces the radiance solid as a function of depth. The apparent optical properties were found by numerical integration of the radiance. A simple three-parameter model was used to simplify study of the dependence of the apparent optical properties on the directional characteristics of the volume scattering function.

Modulation Transfer Function of Sea Water

The modulation transfer function (MTF) of a simple submarine viewing situation is computed as a function of range and sea-water properties. For the cases considered, we found that the MTF follows the simple exponential law, exp(−ω/ω0), where ω is the spatial frequency in lines/deg and where ω0 is a complicated function of the range, scattering albedo, and shape of the scattering phase function. A set of graphs summarizes the dependence of ω0 on the inherent optical properties c and β(γ).

Light Scattering in Central Arctic Ocean: Some Winter Profiles

Measurements for light scattering in an Arctic water column reveal strong gradients and variability of the order of 15 percent in depths of less than 500 meters. The region of variability appears to persist from day to day and is roughly associated with the typical hydrographic features of the region. No definite nephelocline was observed.