The ocean surface layer can absorb only a finite amount of heat before natural processes, like evaporation and precipitation, kick in to cool it down. "Most current modeling studies indicate that the heat would move from the surface to the ocean interior in these cases, but with the new observational data provided by the seal, we found that that's not the case," she said. "We found that these fronts were evident some 500 meters into the ocean interior, not just in the surface layer like many studies suggest, and that they played an active role in vertical heat transport."Īccording to Siegelman, their analysis showed that these fronts act like ducts that carry a lot of heat from the ocean interior back to the surface. "These medium-sized eddies are known to drive the production of small-scale fronts - sudden changes in water density similar to cold and warm fronts in the atmosphere," she said. Analyzing the combined dataset, the scientists paid particular attention to the role smaller ocean features played in vertical heat transport. The satellite data of the ocean surface showed where the swirling eddies were within the current and which eddies the seal was swimming through. Credit: Tandi Reason Dahl › Larger viewįor a new paper published recently in Nature Geoscience, Siegelman and her co-authors combined the seal's data with satellite altimetry data. The blue represents cold, dense water the red areas are less dense and typically warmer. Satellite data are used to identify characteristics of the waters through which the seals swim. This 3D schematic shows how a tagged elephant seal collects data by swimming long distances and diving to great depths through turbulent waters near Antarctica. All the while, it collected a continuous stream of data that has provided new insight into how heat moves vertically between ocean layers in this volatile region - insight that brings us one step closer to understanding how much heat from the Sun the ocean there is able to absorb. The seal made around 80 dives at depths ranging from 550 to 1,090 yards (500 to 1,000 meters) per day during this time. Luckily for Lia Siegelman, a visiting scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, the rough seas posed no challenge for her scientific sidekick: a tagged southern elephant seal.Įquipped with a specialized sensor reminiscent of a small hat, the seal swam more than 3,000 miles (4,800 kilometers) on a three-month voyage, much of it through the turbulent, eddy-rich waters of the Antarctic Circumpolar Current. 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 - as least those of the human variety - to observe and measure. 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 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.īut 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. The Antarctic Circumpolar Current flows in a loop around Antarctica, connecting the Atlantic, Pacific and Indian oceans.
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