Estimating particle composition and size distribution from polarized water-leaving radiance

The sensitivity of the polarization of water-leaving radiance to the microphysical parameters of oceanic hydrosols, specifically to the real part of the bulk refractive index (nbulk) and to the hyperbolic slope of the Junge-type particle size distribution (PSD, ξ) is analyzed using in situ measurements of the underwater polarized light, in both Case I and Case II waters, and multiple scattering computations. Based on comparisons of experimental and simulated data, estimations of the real part of the refractive index and of the slope of the PSD are given. The study yielded results that generally agreed with expectations and that have accuracies comparable to previously published techniques. The analysis also demonstrates that the inclusion of polarization in addition to traditional radiance measurements can be expected to provide complementary information on the nature of particle populations in the ocean.