Ubiquity and seasonality of deep submesoscales in the Southern Ocean revealed by elephant seals.

Deep submesoscales in the Southern Ocean are intensified below the mixed layer and persist year-round down to at least 500 meters, with seasonal variations.

• Why it matters: Understanding submesoscale dynamics below the surface is crucial because they influence vertical exchanges of heat and nutrients, impacting oceanic and climate processes, yet remain poorly documented.
• What they did: Analyzing 133,598 dives by Southern Elephant Seals from 2014 to 2020, researchers used high-resolution data to reveal the presence and seasonal cycle of deep submesoscales, linked to mesoscale eddies.
• The result: Findings suggest that deep submesoscales are generated by mesoscale eddies and may play a significant role in vertical heat and nutrient fluxes, challenging previous assumptions about their importance at depth.