August 2020 - July 2022
Contact Person Dr. Shungu Garaba
MSYS Team Dr. Shungu Garaba
Funding Agency

Discovery Campaign, European Space Agency


Ocean Plastics Polarization Properties

Characterization of light polarization properties of virgin and marine-harvested plastic litter toward remote-sensing mapping of ocean plastics

Satellites are anticipated to be the critical asset for detecting, identifying, quantifying and tracking plastics in marine litter (PML) on large geo-spatial scales. Already, pioneering scientific-evidence based research has shown unique PML spectral reflectance signatures in the ultraviolet (UV, 280 nm) to shortwave infrared (SWIR, 2500 nm) spectrum. Ongoing research is also dedicated to evaluating the need as well as cost of hyperspectral information essential in distinguishing and identifying PML. However, remote sensing of PML can be challenging due to very strong light absorption characteristic of water in the infrared spectrum as well as possible masking of PML signals during atmospheric correction efforts. Complementary optical information is therefore needed to ensure accurate detection of PML. Measurements of polarization state of water-leaving light have been shown to be a significant tool to disentangle complex aquatic light signal to retrieve water constituents. On another hand, subsurface PML might induce surfactants from “bio-fouling” production. In turn, those surfactants will smooth away capillary waves which can be detectable through polarimetric remote sensing. In the context of the future launch the satellite mission PACE (NASA) and 3MI-Sentinel-5 (ESA, EUMETSAT), embarking hyperspectral radiometers and polarimeters, we propose to fully characterize the polarization signature of PML in relation to other natural seawater constituents through: (i) laboratory experimentation, (ii) in-situ measurements, (iii) existing polarization data from older satellite missions (e.g., PARASOL). For this characterization up-to-date polarimetric sensors will be exploited as well as theoretical modeling of light propagation in PML contaminated waters (accumulation zones in the open ocean and estuarine systems) focusing on the water-leaving polarization and surface surfactants/roughness. This is foreseen as an important complementary effort along those of the Copernicus framework of operational satellite missions Sentinel 1 and 2 which have been shown to have potential monitoring application for PML.

(Changed: 2021-11-17)