Conference Agenda

Plastic pollution represents a major threat to marine ecosystems, leading to biodiversity loss and posing risks to human health and safety. The detection of floating plastic objects through in-situ surveys and direct observations remains a challenging task, as these materials are in constant motion across vast and often inaccessible marine regions. In this context, satellite data can play an important role for monitoring and detecting plastic accumulations thanks to their frequent temporal sampling and broad spatial coverage. While most existing methods for detecting floating plastic islands rely on satellite optical data, the use of Synthetic Aperture Radar (SAR) images for plastic marine litter monitoring has so far been limited, although they offer the advantage of being acquired regardless of sunlight or weather conditions. This study aims at investigating the capability of multi-frequency and dual-polarization SAR data to identify a small floating plastic island, approximately 30 m x 3 m in size, deployed in a controlled marine environment in the Gulf of La Spezia (Liguria, Italy) in April 2025. During the experimental campaign, X-band dual-polarization COSMO-SkyMed Second Generation (CSG) and C-band dual-polarization Sentinel-1 (S1) images were acquired with different spatial resolutions and imaging geometries, providing the opportunity to assess the detectability of plastic marine litter using different SAR configurations. The dual-polarization covariance matrix was extracted from both datasets, and different polarimetric techniques were applied, including the H-alpha decomposition and the m-chi decomposition. The objective of the study is to identify an optimal polarimetric parameter capable of detecting the floating plastic island by distinguishing it from the surrounding water. In fact, while calm water surfaces are expected to reflect most of the radar signal away from the sensor, the presence of plastic objects increases the surface roughness, resulting in the signal being scattered in multiple directions. The results of the analysis, which is still ongoing, will be presented during the workshop. However, the preliminary findings already provide promising indications regarding the potential to extract different parameters suitable for this challenging task, also considering the very limited number of literature studies that have explored the use of SAR data for similar applications.