Understanding transport pathways of floating material at the ocean surface requires capturing the contributions of dynamics across multiple spatial and temporal scales. While submesoscale processes are increasingly recognized as key drivers of lateral dispersion, the role of tide-induced dynamics in modulating submesoscale transport remains poorly understood. Here we investigate the impact of tidal forcing on surface Lagrangian pathways by using twin high-resolution NEMO simulations with and without tidal forcing (eNATL60). We focus on a region where there is a high internal-tide signal in the North Atlantic: the Açores Islands.

Our Lagrangian particle experiments reveal that tidal forcing alters surface transport properties. Particles travel longer cumulative distances, but shorter total distances when tides are included, indicating enhanced dispersion via complex pathways. Additionally, tidal forcing introduces variability in surface accumulation patterns, with differences reaching 40% between simulations. These results suggest that tide-generated internal waves interact with the mesoscale field affecting its retention capacity and that tide-induced dynamics can enhance submesoscale dispersion. This creates additional pathways for lateral transport that cannot be captured by tidal currents alone.

These findings have important implications for understanding submesoscale transport processes. The enhanced dispersion and pathway complexity induced by tidal dynamics highlights the need to properly represent fine-scale processes in Lagrangian simulations used for marine connectivity studies, pollution tracking, and ocean clean-up strategies, specially in regions with significant internal tide activity.