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May 242010

From Green Right Now Reports

The eruption of a volcano in Iceland and the BP oil spill in the Gulf of Mexico have drawn attention to the concept of how particles flow both in the air and in water. A pair of researchers at Virginia Tech and at École Polytechnique, Université Libre de Bruxelles, Belgium say that flow, though seemingly random, can be characterized more effectively.

Shane Ross and colleague Francois Lekien reported their findings in the publication Chaos. Their research “will aid scientists and engineers in understanding and in controlling this type of global-scale phenomena, such as pollution dispersion in the atmosphere and the ocean, and large-scale transport of biological organisms, including airborne plant pathogens and respiratory disease agents,” said Ishwar Puri, head of the Engineering Science and Mechanics department at Virginia Tech.

The current BP spill, for instance, could be modeled using Ross and Lekien’s findings to provide greater insight into how the particles might be dragged into the Gulf of Mexico’s Loop Current.

Ross and Lekien said they employed existing scientific principles of Lagrangian coherent structures, which reveals the separation of the atmosphere into dynamically distinct regions, to investigate the shapes of geophysical flow patterns. They used the 2002 discovery of the Antarctic hole in their work because they viewed it as a “prototype atmospheric event” allowing for their studies on topological divisions on the mixing and transport of atmospheric tracers.

Reviewing data from the event, they were able to determine that an isolated “blob of air” was slowly rotating over Antarctica. Lagrangian coherent structures, some which repel nearby air and some that attract it, formed inside the vortex. The vortex pinched off, sending the northwestern part of the ozone hole off into the mid latitude range while the southwestern portion returned to its regular position over the South Pole.

Consequently, they write, when there is more than one vortex flow on a sphere, such as the planet Earth, “complicated spatial structures can arise and evolve, such as the polar vortex split.” They were able to model this event, capturing some of its dynamic features.