The accumulation of plastic debris on land and coastlines and in waterways and garbage patches is one of the greatest ecological concerns of the 21st century. In that context, the sources and pathways of plastic marine debris (PMD) have been increasingly studied in the past ten years. The purpose of this communication was to analyze, thanks to the tracks of two drifting buoys released in May–June 2019 in the North-East Pacific, two features encountered within the Great Pacific Garbage Patch (GPGP): a surface convergence, which could lead to the formation of plastic hotspots, and the persistency of the floating material in this area of the ocean. The evolution of the distance between the buoys was compared with the local circulation field divergence, a Lagrangian plastic dispersal model and sea-level anomalies (SLAs). These analyses highlighted the link between the converging behavior of the drifters and a persistent negative velocity divergence as well as a higher than average-encountered modelled plastic surface density (MPSD). The persistence of the material within the GPGP was observed thanks to the trajectory of the longest persisting drifter in comparison with the trajectory of the GPGP center and extent.

The Ocean Cleanup Foundation is developing floating barrier systems to concentrate and extract buoyant plastics from the global accumulation regions located in the subtropical convergence zones in the world’s oceans. In this context, it is important to understand the transport and accumulation of these floating marine debris. Since marine litter transport is a multi-scale problem, it is important to know the transport of these objects at their very own scale. For this end, two Discrete Particle Models have been implemented in the open-source two-phase Navier-Stokes flow solver Basilisk to study their wave-induced drift: i) using a simple linear interpolation and ii) using the high-order WENO interpolation scheme (Jiang and Wu [1999]) combined with reference frame intrinsic to the particle and its time-dependent submergence. It is shown that in longtime trajectory along the free surface, the two models differ drastically and the sophisticated one shows the best performance. A performance that is highlighted through a wave-induced drift factor defined as the ratio between the wavelength averaged plastic velocity and the wavelength averaged water particle Stokes drift.