Antarctic Circumpolar Current carries 20 percent more water than previous estimates

A press release from the University of Rhode Island: The Antarctic Circumpolar Current transports water around Antarctica and into the Atlantic, Pacific and Indian Oceans, transferring heat and energy around the globe. Quantifying how much water it carries is an important step in understanding climate change and validating the accuracy of climate and oceanographic models.

By analyzing four years of continuous measurements of the current at Drake Passage, the narrowest point in the Southern Ocean, three University of Rhode Island oceanographers have concluded that the current carries 20 percent more water than previous estimates. They also found that the current remains strong all the way to the seafloor.

“It’s important to understand the dynamics of the current so we can understand the impacts of our changing climate,” said Kathleen Donohue, associate professor at the URI Graduate School of Oceanography. “We want to know how the current will respond to changing conditions, so quantifying the transport gives important guidance to the climate models that are trying to predict the future.”

...The Southern Ocean is warming faster than other oceans, and the easterly winds that drive the current have increased significantly in the last 30 years. How the current will respond to these changes is not fully understood. Eddies, or ocean storms, are essential for transferring momentum from the circumpolar winds that drive the current to the sea floor.

To study the dynamics of the current, Donohue, Watts and Teresa Chereskin of the Scripps Institution of Oceanography deployed 35 current and pressure recording inverted echo sounders, which measure oceanic fronts and currents, across Drake Passage in 2007. They retrieved them in 2011. Another more closely spaced array of instruments was also deployed to map circulation and eddy patterns. The instruments collected higher resolution data over a longer period of time than the only other similar study of the Antarctic Circumpolar Current, which was conducted in the 1970s....

A Lambert azimuthal projection of the Drake Passage, by :Geo Swan, public domain