Sarah N. Giddings (Scripps Institution of Oceanography (UCSD), United States); Iury Simoes-Sousa (Woods Hole Oceanographic Institution , United States ); Angelica Rodriguez (Jet Propulsion Laboratory NASA, United States); Joanna L. Carter (Scripps Institution of Oceanography (UCSD), United States)

River plumes are key agents in the global land-ocean exchange, transporting freshwater, nutrients, sediments, and pollutants into the coastal ocean. Despite decades of research, significant gaps remain in our understanding of how river plumes evolve from gravity currents into geostrophic flows, while it mixes with coastal waters. Among the least observed forcings of plume momentum balance and frontal mixing processes, are the barotropic pressure gradients. Driven by differences in water surface height, barotropic gradients are critical in creating cross-frontal acceleration and plume propagation, enhancing convergence and shear stresses that modulate turbulence within the plume.
In this project, we leverage the high spatial resolution of SWOT’s sea surface height data to demonstrate its capability to investigate a river plume's barotropic component. As an example case, we present our analysis of the Rio Grande river plume in southern Brazil. By utilizing the Level 3 Low Rate Unsmoothed (250 m) product, we capture subtle coherent barotropic signatures of the plume, providing unprecedented insights into its dynamics. Expanding this finding we also evaluate SWOT’s potential to observe other systems, while also exploring the use of High Rate products for such analysis.
River plumes offer a tractable system with well-defined forcings, making them ideal for investigating fundamental processes that also govern larger-scale oceanic gravity currents and frontal systems, including submesoscale fronts and storm-driven freshwater lenses. By focusing on river plumes, we aim to develop a robust framework for analyzing the evolution of fronts driven by barotropic forcing.