Abstract

Understanding the 3D dynamics of meso- and submesoscale ocean structures (10–100 km) remains a critical challenge in oceanography. These small-scale eddies, vital to the global climate system, regulate heat balance and transport key elements like salt, carbon, and nutrients. Current methodologies integrate multi-platform in-situ data, remote sensing, and high-resolution model simulations to study these features. However, conventional satellite Sea Surface Height (SSH) measurements struggle to detect smaller currents and eddies. The launch of the SWOT (Surface Water and Ocean Topography) satellite in 2022 represents a breakthrough, offering higher-resolution SSH observations that provide unprecedented insights into ocean dynamics. During SWOT's validation phase in April and May 2023, we conducted two oceanographic campaigns to monitor a small anticyclonic eddy (~12.5 km radius) in the Western Mediterranean Sea. Our study aimed to analyze the eddy's vertical structure using in-situ data and assess SWOT’s capability to detect it. Glider observations revealed the eddy as an intrathermocline feature, and SWOT successfully captured the associated sea level and geostrophic currents, showing significant improvement over conventional altimetry. This study underscores SWOT's ability to resolve both submesoscale and mesoscale structures and highlights the value of integrating satellite and multi-platform data for comprehensive oceanographic insights.