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Study Shows Drifter Data on Surface Currents Critical to Predict Pollutant Transport

Scientists measured the speed of small, short-lived Gulf surface currents using position data from nearly 300 drifters to determine surface current impact on the dispersion of ocean contaminants.

They found that the energy contained in these fluctuating currents makes them primary contributors to the local dispersion and transport of pollutants. Drifter clusters revealed a broad, time-specific view of an area’s currents and provided data that improves transport predictions. These data could be used in real time during an event, such as an oil spill, to improve model forecasts and help contain damage. They published their findings in the August 2014 issue of Proceedings of the National Academy of Sciences: Submesoscale dispersion in the vicinity of the Deepwater Horizon spill.

The Macondo blowout released about 4.4 million barrels of oil into the Gulf over 84 days. During that time, decision-makers needed frequent, accurate forecasts about the oil’s path, travel speed, and spread rate to respond effectively. The region near the Deepwater Horizon site has an array of interacting flow patterns from large eddy-driven deep currents (such as the Loop Current), wind-driven shelf currents, and the Mississippi River plume. Satellite images of the oil slick’s movement showed that dispersal patterns were influenced by both large- and small-scale currents. Existing circulation models captured the mesoscale (larger than 10 km) flows, but the main factors controlling the region’s surface dispersion at the submesoscale (100 meters to tens of kilometers) remained unclear.

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