The three-dimensional structure of fine-scale, vertical velocities in the Southern Ocean inferred from space.

Upper ocean vertical velocities link surface properties to the ocean interior and are typically intensified at small-scale fronts. The small footprint of these velocities and their intermittent nature presents a challenge for determining vertical transport over large regions and long time periods. Here, we diagnose vertical velocities by exploiting the high resolution sea surface height observations collected by the Surface Water and Ocean Topography altimeter along with interior hydrographic measurements from ocean gliders. A surface-height-based reconstruction of interior density and velocity fields permits an estimate of vertical velocities by applying the quasi-geostrophic omega equation at fine spatial scales. Vertical velocities are deep-reaching, have horizontal scales as small as 10 km, and commonly exceed 150 m day-1 throughout the upper 1000 m. The statistical relationship of vertical velocity with vorticity and strain fields are consistent with high-resolution numerical models. This analysis is a step towards generating temporally-varying vertical tracer fluxes for the circumpolar Southern Ocean.