Oral Session 8

The detectability of microplastics in seawater with passive polarized remote sensing

This presentation summarizes research by the Naval Research Laboratory to investigate remote sensing approaches for the detection and characterization of micro-plastic litter in seawater. We first cover laboratory efforts to build up a comprehensive set of inherent optical properties of several common microplastic types, which include measurements of polarized scattering properties, particle size and shape, absorption, scattering, and microscopy. Unique features of the measurements are identified in comparison to natural particles. Using a newly modernized T-matrix code for computing scattering by non-spherical particles, we fit the measurements to theory using an optimal estimation approach. The result is a full scattering Mueller matrix for each plastic particle type. This information is fed into a polarized radiative transfer code approximating gyre conditions, with realistic plastic particle concentrations and vertical distributions found in the literature. With this framework in place, we discuss the simulation results for the radiance and polarization impacts of microplastics in the environment, as well as implications for both in-situ and remote sensing methods.

Robert Foster, U.S. Naval Research Laboratory, USA, https://orcid.org/0000-0002-4186-2147

Ahmed El-Habashi, U.S. Naval Research Laboratory, USA, https://orcid.org/0000-0002-7548-9563

Daniel Koestner, University of Bergen, Norway, https://orcid.org/0000-0002-2252-4847

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