Lagrangian pathways of deep water upwelling in the Southern Ocean State Estimate

Pathways of upwelling of deep waters in the Southern Ocean are investigated using Lagrangian particle trajectories advected offline in the 1/6th°, data-assimilating Southern Ocean State Estimate (sose.ucsd.edu). A total of 18 million particles released at 1000 m - 3500 m at 30° S in each basin were tracked for 60 years by looping velocities from the latest 2005-2010 SOSE iteration. 5% of particles upwelled to 500 m or shallower by the end of the simulation with 37%, 42% and 21% from the Atlantic, Indian and Pacific basins, respectively. Trajectories indicate that particles in the neutral density range 26.7-28.1 from all basins enter the Antarctic Circumpolar Current (ACC), follow the fronts of the ACC, and tend to upwell to the surface ocean toward the southern edge of the ACC and south of the ACC. We analyze differences in upwelling pathways between North Atlantic Deep Water and Indian and Pacific deep waters and explore the role of topography in the upwelling of these deep water masses. These upwelling pathways are important to understanding the 3-dimensional structure of the Southern Ocean overturning circulation and the supply of carbon and nutrient-rich waters to the surface of the Southern Ocean.