The Antarctic Circumpolar Current flows in a loop around Antarctica, connecting the Atlantic, Pacific, and Indian oceans. It is one of the most significant ocean currents in our climate system because it facilitates the exchange of heat and other properties among the oceans it links.
But how the current transfers heat, particularly vertically from the top layer of the ocean to the bottom layers and vice versa, is still not fully understood. This current is very turbulent, producing eddies-swirling vortices of water similar to storms in the atmosphere-between 30 to 125 miles (50 to 200 kilometers) in diameter. It also spans some 13,000 miles (21,000 kilometers) through an especially remote and inhospitable part of the world, making it one of the most difficult currents for scientists-at least those of the human variety-to observe and measure.
To overcome that, Lia Siegelman, a visiting scientist at JPL, which Caltech manages for NASA, and Andrew Thompson, professor of environmental science and engineering, combined data captured by an elephant seal with satellite readings. Equipped with a specialized sensor, the seal swam more than 3,000 miles (4,800 kilometers) on a three-month voyage, collecting a continuous stream of data that would reveal new insight into how heat moves vertically between ocean layers.
“The combination of seal and satellite data helped us to identify pathways between the ocean surface and interior that are not captured in climate models nor easily observed with traditional oceanographic instruments. The Southern Ocean acts as a window to the deep ocean because this is one of the only places where the ocean’s coldest waters rise up to meet the surface. The results of this study have implications for how the Southern Ocean takes up and stores heat and carbon over timescales from decades to millennia,” says Thompson, co-author of an article on the study that was published by Nature Geoscience on December 2.