Loop Current will determine spill’s ultimate fate

Oceanographers track newly formed eddy and where it might carry oil

BOULDER, Colo. — Oil gushing from the Deepwater Horizon site in the Gulf of Mexico will reach the Atlantic Ocean within six months, says oceanographer Synte Peacock. Exactly when is all down to an eddy that broke off of the infamous Loop Current southwest of Florida on June 12.

IN THE LOOP Computer simulations suggest that oil from the ongoing Deepwater Horizon spill will reach the Atlantic Ocean no later than October. Tim Scheitlein and Mary Haley/NCAR

Peacock, of the National Center for Atmospheric Research in Boulder, Colo., usually studies how the ocean’s water absorbs atmospheric gases. But after the Deepwater Horizon platform exploded on April 20, she realized her computer models could be used to follow where the oil gushing from the seafloor might end up.

Her simulations, announced in a press release on June 3, made headlines worldwide. No surprise: the simulations suggested that, once the oil became caught up in the Loop Current, it would be funneled into the Atlantic within weeks.

Talking with reporters at NCAR on June 14, Peacock explained how some news outlets misrepresented her work by glossing over a few major caveats. Most important, the work simulated the movement of dye  — not viscous oil  — injected in the upper layers of the ocean — not the deep seafloor — for a total of two months — not the ongoing no-end-in-sight disaster.

The simulations underscore how complicated it can be to track the movement of subsurface oil. “We saw large differences in details in how oil dispersed, depending on local eddies and currents in the Gulf,” she says. Still, “no matter what you do it’s very, very hard in our model to find a scenario where dye is kept within the Gulf for a period of longer than six months.”

The Loop Current circulates clockwise off the southwestern coast of Florida. About once or twice a year, it pinches off an eddy that either wanders around the Gulf before dying out, or eventually reattaches with the main Loop current.

The unusual thing about the Loop Current this year, Peacock says, is that it was located much more to the south and east than usual when it pinched off its new eddy. Eddies have popped off in this location twice before in recent years, she says. One of those times the eddy wandered to the west, toward Texas, before dissipating. The other time it reattached with the Loop.

Where the new eddy goes will strongly influence exactly where the oil ends up, she says. When it does reach the Atlantic, she notes, the oil will not necessarily wash ashore on beaches in a goopy mess. The oil might stay far out to sea, or be extremely diluted by the time it gets to the Atlantic.

Her team is now working on simulations of what will happen if the oil keeps gushing for months to come.

Alexandra Witze is a contributing correspondent for Science News. Based in Boulder, Colo., Witze specializes in earth, planetary and astronomical sciences.

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