Horizontal and vertical dispersion in a wind-driven oceanic gyre model.

This article investigates the horizontal and vertical dispersion of passive tracers in idealized wind-driven subtropical gyres using numerical simulations of synthetic particles advected by theoretical velocity fields. The study focuses on the classical Stommel circulation, surface Ekman drift, inertial effects related to particle size and buoyancy, and turbulent diffusion modeled stochastically. Results show that the Ekman drift inhibits horizontal dispersion by concentrating particles near the gyre center, a behavior intensified by inertial effects, which may better explain the formation of garbage patches than Ekman dynamics alone. Vertically, particles sink more on the western side of the basin due to Ekman pumping, and while surface tracers initially cluster near the gyre center, they disperse horizontally once below the Ekman layer, with sinking depth influenced by horizontal diffusivity. The study highlights the importance of considering both inertial and Ekman effects in understanding tracer distribution and suggests further research on inertial effects in vertical sinking processes.