Light Scattering by Marine Particles: Modeling with Non-spherical Shapes

The inherent optical properties (IOPs) of marine particles are most-often modeled and interpreted by assuming that they are homogeneous spheres. Although this approach has been fruitful, the next logical step in modeling the IOPs of marine particles is to abandon the normally-employed spherical approximation and use more realistic idealizations of their shape. The advent of computer codes capable of handling more complex shapes, and the increased computational speeds now available, suggest that particle modeling employing simple non-spherical shapes, e.g., disks, rods, etc., could become routine. For example, Gordon and Du (2001) used a two-disk model to try to reproduce the backscattering by coccoliths detached from E. huxleyi; however, they found that, while the resulting spectral variation of the backscattering cross section agreed with experiment, its magnitude was low by a factor of 2-3. As simple shapes are still at best poor approximations to real particles, i.e., real particles display significant inhomogeneity, one is led to examine the influence of such inhomogeneities.