Characteristics of Mesoscale-to-Submesoscale Eddies in the Labrador Sea

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In this talk, we present the results highlighted in a recent publication

Bendinger, A., A. F. Dilmahamod, A. Albert, J. Le Sommer, and J. Karstensen, 2025: Characteristics of Mesoscale-to-Submesoscale Eddies in the Labrador Sea: Insights from Ship Observations. J. Phys. Oceanogr., 55, 2037–2057, https://doi.org/10.1175/JPO-D-24-0216.1

Characterization of coherent eddies is often based on gridded satellite altimetry products. In subpolar regions, these products face limitations due to their low spatial resolution and the decreasing Rossby radius of deformation at higher latitudes, making in situ observations indispensable for eddy characterization. Here, we present a census of mesoscale-to-submesoscale eddy characteristics in the Labrador Sea—a region where eddies play an important role in winter deep convection and subsequent restratification. Using ship-based observations, we fit an idealized eddy solution to horizontal velocity measurements acquired along ship tracks, determining an optimal eddy center and other key eddy properties. Based on three research cruises, we reconstructed 40 eddies ranging from 3 to 39 km in radius (mean 15 km) and azimuthal velocity between 7 and 58 cm s−1 (mean 26 cm s−1). The azimuthal velocity structure implies, to a large extent, solid-body rotation in the eddy’s inner core, while opposite signs of vorticity in the outer ring suggest strong vorticity shields. When compared to ship-based observations, the eddy field representation in gridded altimetry products is significantly distorted, with many eddies being underrepresented or undetected. This is even the case for larger-scale features despite having an eddy signature in the along-track altimetry product, which appears to be suppressed in the subsequent mapping methodology. Finally, comparisons with submesoscale-permitting numerical simulation output show favorable agreement, giving confidence in both the ship-based reconstruction and the numerical model’s realism in representing high-latitude eddy dynamics.

Significance Statement

Oceanic eddies in the Labrador Sea play an important role in advecting heat, salt, and other properties to the interior basin with implications for winter deep convection and subsequent restratification of the homogenized water column. Using ship-based observations, our research provides a basinwide eddy characterization, capturing a broad range of spatial scales with radii from 3 to 39 km. We show that conventional satellite altimetry distorts eddy properties at high latitudes, where eddies are smaller in size and often remain undetected. By expanding the census of eddy characteristics in the Labrador Sea, our study offers a valuable dataset for assessing eddy dynamics in high-resolution numerical models, which often lack direct validation.

Our speaker

Fehmi Dilmahamod is a postdoctoral researcher at GEOMAR. Fehmi works on

• Oceanic (sub)-mesoscale dynamics
• Large-scale ocean circulation
• Biophysical coupled processes
• Ocean Observation

His bio is available here.

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