![]() The ACC flows around the northern edge of the Southern Ocean and is not only the world’s strongest current, but also the only major current that circles the globe unimpeded by continents. Westerly winds circling Antarctica blow cold, carbon-dioxide-rich surface water northward from the continent across the Antarctic Circumpolar Current (ACC). In the Southern Ocean, strong ocean-atmosphere interactions and eddies largely drive upwelling, researchers have found. The researchers were additionally able to determine how much water from each ocean basin made it up what they call this “spiral staircase,” and believe this journey happens much quicker than previous estimates suggest. The study, published in the journal Nature Communications, also reveals that strong eddies, caused by topographical interactions at five locations within the current circling Antarctica, play a major role in this upwelling process. The research team includes scientists from MIT, the Scripps Institution of Oceanography, Princeton University, the Geophysical Fluid Dynamics Laboratory, the Los Alamos National Laboratory, the University of Washington, and NASA's Jet Propulsion Laboratory. Now researchers have found that deep, relatively-warm water from the three ocean basins enters the Southern Ocean and spirals southeastwards and upwards around Antarctica before reaching the ocean’s mixed layer, where it interacts with the atmosphere. Yet the three-dimensional structure of the pathways that these water particles take to reach the Southern Ocean’s surface mixed layer and their associated timescales was poorly understood until recently. This overturning completes the global circulation loop, which is important for the oceanic uptake of carbon and heat, the resupply of nutrients for use in biological production, as well as the understanding of how ice shelves melt. After entering the Southern Ocean they overturn - bringing water up from the deeper ocean - before moving back northward at the surface. ![]() Through observations and modeling, scientists have long known that large, deep currents in the Pacific, Atlantic and Indian oceans flow southward, converging on Antarctica. Since Captain James Cook’s discovery in the 1770s that water encompassed the Earth’s southern latitudes, oceanographers have been studying the Southern Ocean, its physics, and how it interacts with global water circulation and the climate.
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