• Eli is a contributing correspondent for Science magazine.

Slick Models Suggest 'It's Anyone's Guess' When Oil Will Reach Atlantic

15 June 2010 4:46 pm

BOULDER, COLORADO—As the gulf oil spill grows, scientists here are refining models of the slick's behavior in hopes of developing a more accurate picture of its future movements. They are keeping a close eye on a particular eddy that could determine when the oil might reach the Atlantic Ocean.

The scientists are focusing on the Gulf of Mexico's Loop Current, which brings water from the gulf around Florida and up the Atlantic Coast. In early June, oceanographer Synte Peacock of the NationalCenter for Atmospheric Research (NCAR) and other scientists released several simulations of the way the slick might interact with the current. An eddy roughly 70 miles wide has spun off in the past few weeks from the current, roughly 100 miles west of the southern tip of Florida, Peacock told reporters yesterday, adding that it now shows a slight reattachment. (Looking at 17 years of data, Peacock saw similar behavior only twice, in 1998 and 2003.)

The modeling suggests that when the key eddy remained connected to the current, water from the gulf reaches the Atlantic in roughly 70 days. When it disconnects, it can take 4 to 6 months . "It's anyone's guess how the eddy will behave," says Peacock, who calls its behavior "highly unpredictable."

Peacock says there's "clearly some" oil in the Loop Current already. That oil, she noted, could be pulled from the gulf around Florida if the eddy were to recombine with the rest of the current's structure.

For more on the gulf oil spill, see our full coverage.

NCAR scientists emphasize the limitations of the model. For starters, it uses what amounts to a digital dye, which lacks the physical properties of oil. It doesn't simulate the formation of slicks or tarballs, and the dye doesn't get eaten by microbes or weathered by waves. The model also omits hurricanes. Because officials lack definitive knowledge of the amount of oil gushing out, the model has included calculated dilutions of oil, not actual modeled concentrations of oil in the water. So although the model might offer insights on possible scenarios that short-term forecasts lack, it is not a tool for accurate forecasting.

In an effort to make the model slightly more realistic, Peacock says, her team has recently doubled, from 2 to 4 months, the length of time in which oil is escaping through the well on the sea floor. When we started these simulations, she says, "We thought by June 20 they'd have the well capped."

The team is planning to submit its new modeling data to a journal instead of releasing it to the public, as it did earlier this month. When a journalist asked Peacock, "If there was ever a time to release data, wouldn't now be it?" her answer reflected the novelty of the current situation. "We can't put out all our data on press releases [without peer review]," she says. "It's a very unusual situation for oceanographers. ... Hopefully, the paper will get accepted soon and we can put out the data."

How likely is that to happen? Peacock's modeling uses typical winds based on historical patterns and physical equations of the ocean. Earlier this year, in research unrelated to the spill, she and others ran the ocean model for 120 simulated years. Then, after the spill, they looked for various years with different behaviors of the current, and added digital "dye" to each on 20 April, the day this year that the Deepwater Horizon platform caught fire and exploded, triggering the spill.

For more on the gulf oil spill, see our full coverage.

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