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As loop current splits, South Florida catches a break

In the oil spill battle of man vs. nature, nature is pulling off a valiant feat.

The powerful Gulf of Mexico loop current, which seemed primed three months ago to thrust oil to the Florida Keys and beyond, suddenly changed course and helped protect much of Florida's cherished shorelines.

Now, with BP capping the leak, a growing number of scientists think the loop current will help spare South Florida and the east coast from large amounts of BP oil.

It's a bit of serendipity amid calamity.

"Things look excellent," said Frank Muller-Karger, a biological oceanographer at the University of South Florida. "They have not looked better in the last two months."

Pollution from the Deepwater Horizon site has blanketed Pensacola and parts of Louisiana and Alabama. Texas saw tar balls.

So far, most of Florida has caught a break.

Tampa Bay and the west coast have been spared because they are separated from the spill by the shallow, 150-mile-wide West Florida continental shelf. It would probably take days of tropical storm-force winds to push oil to the shoreline.

The Keys, which were supposed to get oil weeks ago, have seen nothing from the BP spill, researchers say. It's the same story along Florida's east coast.

In fact, a Coast Guard lab in Connecticut testing oil samples from the gulf and East Coast says it has found no matches with BP oil south of the Panhandle.

"People had good reason to worry," said Michelle Wood, a National Oceanic and Atmospheric Administration oceanographer studying the loop current. "It seems we've kind of dodged a bullet on that so far."

The loop current, part of the Gulf Stream, begins in the narrow passage between Cuba and Mexico's Yucatan Peninsula, where it speeds north at 5 knots into the north central gulf.

The Earth's rotation and underwater features known as shelves ultimately turn the loop to the south, then east through the Florida Straits, where it joins the Gulf Stream and heads north up the coast.

Every nine months or so that changes because of numerous currents and the topography of the gulf floor.

The top of the horseshoe-shaped current is clipped off, becoming a spinning ring of water known as an eddy. The revised loop current then takes a more easterly course, traveling from the Yucatan through the Florida Straits, well south of the oil spill.

"It's just a natural cycle, and it goes back and forth," said Muller-Karger. "It's a completely cyclical thing."

This time, it happened in May.

The current's top part became a massive eddy spanning hundreds of miles. Scientists named it Franklin. The bottom part reshaped itself.

The threat of BP oil being swept to South Florida and beyond was lost.

"The gulf loop current is a living, breathing thing that takes on a life of its own and shapes things in a very fundamental way," said Doug Rader, chief oceans scientist at the Environmental Defense Fund.

Scientists are watching what comes next.

The loop current will eventually reshape itself. Will it be soon enough to move oil south?

"It's not only hard to predict, it's almost an art to forecast," said Muller-Karger.

For now, many scientists say the likelihood of large amounts of BP oil being carried to South Florida or the East Coast are diminishing with each passing day.

With the leak capped, the oil has time to dissipate, evaporate and break into tar balls. And when the loop current resumes its more northerly course, it doesn't necessarily mean an oil rush to South Florida.

"It's not an immediate rapid freight train that goes from the spill site to the Florida Keys, but rather a more complicated system of handoffs," Rader said.

As hurricane season begins in earnest, keeping oil offshore is up to the wind. And, of course, humans.

"There's no question that the capping of this well is what we all really wanted to see," said Muller-Karger. "From now on, it will all be a dilution process — if they continue to keep the thing capped."

Stephanie Hayes can be reached at or (727) 893-8857. Katie Sanders can be reached at ksanders@sptimes or (727)893-8804.

As loop current splits, South Florida catches a break 07/21/10 [Last modified: Wednesday, July 21, 2010 10:16pm]
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