Figure 1 — Float trajectories: This figure shows the trajectories of floats released within the Rio de la Plata estuary. Colors correspond with their SSS. The left panel shows upstream trajectories and the right panel downstream trajectories. In this experiment 1612 floats were released every 10 days starting in January 8th 2008 and ending in December 23rd 2008. The float trajectories were calculated offline using a 2-day average of the 3-D velocity field of the model. Each float was tracked for a period of 540 days. Of the 50,156 floats released 38,548 left the shelf within the mixed-layer and 10,608 at depths larger than 50 m.