Klocker, AndreasFerrari, RaffaeleLaCasce, Joseph H2015-12-130022-3670http://hdl.handle.net/1885/71964Particle- and tracer-based estimates of lateral diffusivities are used to estimate the suppression of eddy mixing across strong currents. Particles and tracers are advected using a velocity field derived from sea surface height measurements from the South Pacific, in a region west of Drake Passage. This velocity field has been used in a companion paper to show that both particle- and tracer-based estimates of eddy diffusivities are equivalent, despite recent claims to the contrary. These estimates of eddy diffusivities are here analyzed to show 1) that the degree of suppression of mixing across the strong Antarctic Circumpolar Current is correctly predicted by mixing length theory modified to include eddy propagation along the mean flow and 2) that the suppression can be inferred from particle trajectories by studying the structure of the autocorrelation function of the particle velocities beyond the first zero crossing. These results are then used to discuss how to compute lateral and vertical variations in eddy diffusivities using floats and drifters in the real ocean.Keywords: Antarctic Circumpolar Currents; Autocorrelation functions; Drake passage; Eddies; Eddy Diffusivities; Eddy mixing; Lateral diffusivity; Mean flow; Mesoscale process; Mixing length; Particle trajectories; Particle velocities; Sea surface height measurement Diffusion; Dispersion; Eddies; Mesoscale processes; Mixing; Turbulence201210.1175/JPO-D-11-0205.12016-02-24