Sediment resuspension and oil droplet entrainment by Langmuir supercells*

Interaction between the wind-driven shear and the wave-induced Stokes drift in the upper ocean leads to Langmuir cells consisting of wind-aligned counter-rotating vortices. In inner-shelf regions undergoing strong wind and wave forcing during storms, Langmuir cells can reach the bottom of the water column while increasing in intensity and coherency. These full-depth Langmuir cells have been denoted as Langmuir supercells or LSCs because they provide a dominant mechanism for sediment resuspension and subsequent lateral transport by the current. LSCs were first discovered through their resuspension of sediments along the upwelling limbs of the cells. In the presence of oil broken up into droplets at the surface of the sea, LSCs also serve to entrain the droplets along the downwelling limbs of the cells. Lagrangian particle tracking simulations will be presented demonstrating the sediment resuspension and oil droplet entrainment dynamics induced by LSCs. Accumulation zones of sediment particles and oil droplets induced by LSCs and dispersion across these zones will be investigated to assess the potential mixing between oil and sediments which can lead to the formation of oil-particle aggregates.