Understanding Ocean Surface Response to Hurricane Idalia Using SWOT Altimetry in the Gulf of Mexico

Abstract In this work, novel Surface Water and Ocean Topography (SWOT) KaRln altimetry data is leveraged to observe the surface ocean dynamics of the Gulf of Mexico (GoM) before, during, and after the passage of Hurricane Idalia in August 2023. SWOT observes features like the Loop Current (LC) and mesoscale Loop Current Eddies of higher resolution than global data‐assimilated model solutions and conventional nadir‐looking altimeters. SWOT resolves more small‐scale Loop Current Frontal Eddies (LCFEs) with its 2 km horizontal resolution, particularly off the West Florida shelf. These cold‐core LCFEs show cool sea surface regions that correspond with regions of high chlorophyll‐a (Chl‐a) and low salinity before and during Hurricane Idalia's passage. The increased presence of cold‐core, cyclonic LCFEs during the passage of Hurricane Idalia could have contributed to a decrease in its intensity.