Minghai Huang (Texas A & M University, USA); Ping Chang (Texas A & M University, USA); Patrice Klein (Caltech, USA)

Ocean mesoscale eddies manifest as anomalies in sea surface height (SSHA) and temperature (SSTA), with SSTA reflecting near-surface thermal structure and SSHA integrating density variations throughout the water column; their spatial coherence—quantified by localized SSHA–SSTA spatial correlation—thus serves as a key diagnostic of eddy vertical structure and heat transport. Integrating satellite observations, reanalyses, and a high-resolution climate simulation, we demonstrate that SSHA–SSTA correlation is strongest where large-scale SSH and SST gradients align, as measured by their intersection angle theta, which explains global correlation patterns more effectively than eddy kinetic energy alone. Regions of gradient misalignment (high angle) mark hotspots of non-traditional eddies—warm-core cyclones and cold-core anticyclones—that would drive distinct air–sea fluxes and biogeochemical responses, necessitating their inclusion in climate model parameterizations. A robust global increase in SSHA–SSTA correlation was found over the altimetry era, consistent with rising traditional eddies and declining non-traditional ones amid intensified eddy activity. These findings carry critical implications for quantifying eddy-driven heat transport and for surface quasigeostrophic methods that infer subsurface structure from surface coherence.