Martín Saraceno (CIMA/CONICET-UBA, Argentina); Sebastián Cornejo Guzmán (CIMA/CONICET-UBA, Argentina); Laura Ruiz Etcheverry (CIMA/CONICET-UBA, Argentina)

The study of oceanic submesoscale processes represents a challenge for both in situ observations and satellite data. In recent years, the use of drifting buoys has gained importance as a Lagrangian tool to investigate these processes, enabling an analysis that follows the flow and examines its properties while removing the advective component. During a research cruise in January 2025, a set of 5 drifters anchored at 15 m depth (type A) and 18 drifters anchored at 50 cm depth (type B) were deployed in the Uruguayan shelf-break, under the influence of the Brazil Current. Type A drifters also measured surface temperature and temperature and conductivity at 12 m depth. The buoys drifted for 36 hours transmitting its position every 30 minutes (A) and 10 minutes (B). The drifter trajectories revealed distinct circulation patterns between the two drifter types. For type B drifters, we examined the influence of Ekman transport, tides, and inertial motions. Reconstructed trajectories—obtained by subtracting each drifter’s mean velocity and the tidal current—highlight inertial oscillations as the dominant residual signal. Type A drifters displayed trajectories coherent with geostrophy. The observed trajectories will be used to compare conventional Level-4 altimetry products with datasets enhanced with SWOT observations. Additionally, vertical transport is to be estimated from kinematic properties at two depth levels, with the aim of advancing toward a Lagrangian characterization of submesoscale processes in the Southwestern Atlantic. This work has been made possible thanks to the Pampa Azul B6, OSTST TOSTO, and SWOT PATASWOT projects.