by Tanya Thomas on  May 25, 2010 at 3:10 PM Environmental Health
 2002 Antarctic Ozone Hole Break-up Can Be Understood By Recent Pollution Dispersion
The eruption of the volcano in Iceland wreaked havoc as particles from the natural disaster travelled over Europe, forcing closures of major airports. But now, the seemingly random flow of particles can be analyzed to understand and control global phenomena such as this.

According to work done by Virginia Tech's Shane Ross of the engineering science and mechanics (ESM) department and his colleague Francois Lekien of Icole Polytechnique, Universiti Libre de Bruxelles, Belgium, these particles can be characterized more effectively.

The research will help them analyze 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 ESM department at Virginia Tech.

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.

Talking about the discovery of the Antartic ozone hole, which became the focus of the atmospheric science community, Ross described the event - when the ozone hole split in two, allowing one of its fragments or regions to reassert its position over the Antarctic Pole while the other one spread into the mid-latitude regions, it implied "a sudden stratospheric warming."

The scientific explanation, Ross said, is "they are produced by the dynamic momentum force resulting from the breaking and dissipation of planetary-scale Rossby waves in the stratosphere."

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.

"This model is very relevant both in atmospheric and oceanographic settings when one considers large-scale phenomena where the spatial geometry of the Earth's surface becomes important. The full spherical geometry, as opposed to tangent plane approximations, is particularly important when considering global streamline patterns generated by a given vorticity distribution...These patterns, in turn, provide the dynamical templates by which one can begin to understand the chaotic advection of particles in a vortex-dominated flow."

The study is published in the publication Chaos.

Source: ANI

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