Abstract

Atmospheric Rivers (ARs) are key drivers of extreme precipitation and hydrological variability along the west coasts of continents. While many studies have focused on their atmospheric impacts, the oceanographic response remains underexplored. Using remote sensing and in situ observations, this study examines how ARs affect river plumes, hydrodynamics and biogeochemical conditions in central-southern Chile (33–40° S). Synoptic atmospheric conditions associated to the passage of different oriented AR (i.e., Tilted and Zonal ARs) produce contrasting river plume dynamics, while TARs favor coastally trapped and southward-advected plumes by the northerly winds, ZARs generate dispersed and offshore plumes influenced by southerly winds. High resolution mooring data show that both TARs and ZARs initially enhance vertical mixing and currents by strong winds, followed by stratification due to the arrival of a river plume. Biogeochemical samplings before and after the passing of a series of ARs show that TARs increase surface nitrates, silicic acid and chlorophyll-a more than ZARs. The results provide novel insights into the response of river plumes and water column changes to the passage of ARs in the coastal ocean. © The Author(s) 2025.