Wave effects on the dispersal of buoyant particles

Michelle DiBenedetto1, Jeffrey R Koseff2 and Nicholas T Ouellette2, (1)Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, United States, (2)Stanford University, Civil and Environmental Engineering, Stanford, CA, United States
The dispersal of buoyant particles at or near the ocean surface is influenced by a variety of physical factors including wind, waves, and turbulence. The interplay between these mechanisms controls the transport and dispersion of particles across and below the ocean surface. In the multiple studies that have focused on how turbulence and wave effects (e.g. breaking waves, Langmuir cells) affect particle dispersal, the free surface is often assumed to be flat. Therefore, the effects of an unsteady ocean surface due to surface gravity waves remain unknown in this context. Using numerical models and analytical techniques, we examine the effects of waves on the vertical and horizontal distribution of buoyant particles. We simulate particle dispersal scenarios under progressive deep-water wave trains, and find that waves result in non-uniform horizontal distributions of particles. We also find that the waves can modulate the equilibrium vertical distribution of buoyant particles mixed under a free surface. Our results will also be applied towards interpreting surface trawl samples of buoyant particles, such as microplastics, under wavy conditions.