ABSTRACT

Vertical motions in the ocean are responsible for the transport and subsequent storage of heat, carbon and nutrients. To date, ocean mesoscale eddies (50-300 km) and small-scale diffusive mixing (<10 m) are traditionally invoked to explain oceanic vertical transport between the ocean interior and the surface. In addition, submesoscale motions (1-50 km) have also been identified as a key process for oceanic vertical transport but solely confined to the mixed layer. Here, using high-resolution observations collected by an elephant seal in the Southern Ocean, in combination with satellite altimetry data, we show that vigorous vertical motions (i) are associated with energetic submesoscale fronts located in-between mesoscale eddies, and (ii) extend from the surface down to depths of 500 m, i.e. well below the depth of the mixed layer. These intense submesoscale verticalmotions, which locally exceed 200 m/day, are an important yet unexplored pathway connecting the ocean interior to its surface, and potentially has major implications for the biogeochemical and climate systems.