Ocean eddies on the mesoscale (O(100) km) contain most of the kinetic energy and play an essential role in ocean dynamics on climatic scales. The submesoscales (below O(10) km) are associated with smaller, faster eddies, as well as filaments and temperature fronts, and are crucial due to both the intense vertical transport (of heat and nutrients) they induce and to their role in energy transfers. It is possible to understand the horizontal dispersion of Lagrangian drifters observed at mesoscales using predictions from turbulence theory. At submesoscales, deviations from these predictions can provide information on the interaction between fast processes (frontal dynamics, tidal waves) and slower (geostrophic) processes, in order to better understand energy transport and transfer properties at fine scales. The aim of the internship is to explore the statistical properties of Lagrangian particle transport at the ocean surface using state-of-the-art realistic numerical simulations. Particular attention will put on particle clustering (due to submesoscales), whose mechanisms are not fully understood. The methodology will rely on the analysis of statistical indicators of particle aggregation and other tools from turbulence theory. This will help to propose modifications of existing theory to include fast dynamical processes.