Scientists at the Eidgenössische Technische Hochschule and University of Miami found that some of the largest ocean eddies on Earth are quite similar to the mysterious black holes of space. An ocean eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. Our climate has influenced huge ocean eddies over 90-miles in diameter that rotate and drift across the ocean. The number of eddies in the Southern Ocean are on the rise, increasing the northward transport of warm and salty water. Scientists have been unable to quantify the impact of ocean eddies so far because the exact boundaries of these swirling bodies have remained undetectable. However, researchers writing in the Journal of Fluid Mechanics say they have developed a new mathematical technique to find water-transporting eddies with coherent boundaries. In order to find an eddy, researchers must pinpoint coherent water islands in a turbulent ocean. The rotating and drifting fluid motion appears chaotic
to the observer, but the team was able to restore order to this chaos by isolating coherent water islands from a sequence of satellite observations. They found that these coherent eddies turned out to be mathematically equivalent to black holes. The mass of a black hole is so great that it can attract everything that comes within its region, bringing an object closer and closer until it gets sucked down into its vortex. Not even light can escape a black hole. However, as a light beam gets closer to a black hole, it can dramatically bend and come back to its original position, forming a circular orbit. A barrier surface formed by closed light orbits is known as a photon sphere. The team discovered similar barriers around certain ocean eddies. In these barriers, fluid particles move around in closed loops, and nothing can escape from the inside of these loops. These barriers could help identify coherent ocean eddies in the vast amount of observational data available. ”Mathematicians have been trying to
understand such peculiarly coherent vortices in turbulent flows for a very long time,” George Haller, Professor of Nonlinear Dynamics at ETH Zurich, said in a statement. The team’s results could help resolve a number of oceanic puzzles, including everything from climate-related questions to the spread of environment pollution patterns.