Abstract:
The optical properties of randomly oriented, spheroidal marine particles are
modeled using both numerical and analytical techniques. The optical properties
examined are attenuation, scattering, absorption and backscattering. The optical
properties are compared to those of equal-volume spheres. The optical properties of
very small particles, relative to the wavelength of the incident light, with a very small
refractive index relative to that of the surrounding medium, such as viruses, proteins,
and small bacteria show no dependence on shape. The optical properties of larger
bacteria and small phytoplankton such as Synechococcus are smaller than those of an
equal volume sphere. The optical properties of the remainder of the particles, which
includes most phytoplankton, show considerable variation in shape effects. Very large
particles are shown to converge to known limits, with spherical particles always
underestimating the optical properties of equal-volume spheroids.
For populations of particles hyperbolically distributed with respect to both size
and shape, it is found that the attenuation coefficient is underestimated by equal
volume spheres by as much as a factor of 2.
