TECHNOLOGY IN THE GULF Gliders Offered Way to Monitor the Loop Current Would oil hit the East Coast? A shifting current held the key. n the initial days of the Deepwater Hori- zon disaster, a spotlight shone on a little- knownI watery cog in the ocean’s circulatory machinery: the Loop Current in the Gulf of Mexico. Where that chaotic current was located and how it was moving in the spring of 2010 would determine whether oil would spread widely beyond the Gulf and cause much more damage and demand even greater emergency responses. Breck Owens, Ocean Remote Sensing Group, Johns Hopkins University Applied Physics Laboratory The Loop Current (orange) is like a big river of warm water that comes from the Caribbean a physical oceanographer at Woods Hole Sea. It typically loops up close to Louisiana (and the site of the Deepwater Horizon oil rig), Oceanographic Institution (WHOI), had a then swoops back down through the Florida Straits and into the Atlantic. roving robot able and ready to answer that crucial question. “One of the concerns was that the oil its southern end and pinches off a swirl- To track the ocean’s ever-changing spill was going to get into the Loop Current, ing circle of water called an eddy, which currents, scientists at WHOI and Scripps which is a big, warm current that comes drifts westward and eventually bumps into Institution of Oceanography developed the from the Caribbean between the Yucatán the coast of Texas. When that happens, the Spray glider, a 6-foot, 110-pound, torpedo- Peninsula and Cuba into the Gulf of Mex- Loop Current temporarily loses its loop. shaped underwater vehicle. It can remain ico,” Owens said. “It sometimes loops up It flows more directly from west of Cuba at sea for months, collecting measurements relatively close to Louisiana, and then trav- to the Florida Straits, bypassing the central and periodically rising to the surface to els back down past Key West, through the and northern parts of the Gulf. transmit data back to scientists on shore. Florida Straits, and feeds the Gulf Stream. The gliders were based on instrumented Under the worst-case scenario, if the Loop Chaos and currents floats developed in the 1990s. “We realized Current had been near the Deepwater Loop Current eddies form “in a random, that if they grew wings, we could then Horizon site, it could have brought oil chaotic way,” Owens said. “It’s like letting control them,” Owens said. “They could all the way past Key West, all the way up go of a garden hose: You know it’s going to fly through the water, whereas the floats the east coast of Florida, all the way up flop around, but at any given time, you can’t only traveled with the water.” to Cape Hatteras, and then spread it out predict exactly where it’s going to be. The Via the same system that sent data to into the North Atlantic.” Loop Current is part of the turbulent ocean. shore, the scientists could send commands The critical word in that description is We know eddies are going to form, we to the gliders. “We could control the gliders, “sometimes.” Three or four times a year, know roughly how often it happens, but ex- tell them where to go, and keep them in a the loop in the Loop Current narrows at actly when it’s going to happen is something region for a long time,” he said. In its first we have great difficulty predicting.” long-distance test, in 2004, Owens remotely piloted a Spray glider over 50 days, from “The East Coast got Martha’s Vineyard to Bermuda, proving it could be steered across one of the ocean’s off the hook because strongest currents, the Gulf Stream. Nature was kind.” Glider pilot —Breck Owens Even before the big spill, Owens was keenly interested in investigating the Loop // SEE THE VIDEO @ Current. The powerful current has strong www.whoi.edu/deepwaterhorizon/chapter5 impacts on navigation and infrastructure (such as oil rigs) in the Gulf, as well as on 6 Oceanus MagaZine Vol. 48, No. 3, Fall 2011 | www.whoi.edu/oceanus hurricanes. During the summer of 2005, for launched on June 7, and Owens remotely family that I’ve kind of taken on, to try to example, the Loop Current was in a posi- piloted it through the Gulf for three watch over.” tion that brought deep pools of warm water months. He also coordinated with research- In early June 2010, the Loop Current into the Gulf. Hurricanes Katrina and Rita ers who subsequently launched and steered formed an eddy. It effectively acted as a both passed over the warm waters of the other gliders in the Gulf. whirling barrier, blocking spilled oil from Loop Current, absorbing more heat energy “People in the oceanographic community reaching the current farther south and that allowed them to intensify. rallied to help in this disaster,” Owens said. flowing through the Florida Straits. For these reasons, BP, owner of the “I’m incredibly proud of the job we did, “I think we, as a country, were really Deepwater Horizon oil rig, spends consid- volunteering in the beginning, trying what- lucky,” Owens said. “The East Coast got erable sums monitoring the Loop Current. ever possible to make measurements to help off the hook because Nature was kind.” In winter, satellites can detect the warm provide information to better predict where —Lonny Lippsett Loop Current, which contrasts with cooler the oil spill was going. It speaks well of our Gulf of Mexico waters. But as the shallow community, and our concern for the ocean.” Preparation of the glider and part of its Gulf warms up in summer, satellites can’t deployment were paid for by residual funds easily discern temperature differences that Like family from a contract with BP and by a National a glider can. Owens checked on the glider several Science Foundation Rapid Response Research Owens sees the day when “gliders could times a day when it surfaced. “You have to grant. Owens was supported by the W. Van be the basis for an ocean-observing system look at the data, try to decide what Alan Clark Jr. Chair at WHOI. for oil spill monitoring, field op- erations, hurricane prediction, and navigation forecasts.” In 2008, he undertook a two-year project funded by BP to demonstrate that gliders could offer an efficient and effective way to keep track of the current’s meanderings. they mean, So it was not surprising that a glider and give the glider new was in the vicinity shortly after the oil rig instructions,” he said. “It was a exploded on April 20, 2010. Technicians few hours a day, every day, for three Courtesy of Patrick Rowe from Scripps and WHOI equipped it with months. You just worked it into your The Spray glider, developed by scientists at sensors to measure seawater temperature schedule. My wife told me several WHOI and Scripps, is a 6-foot, 110-pound and salinity, current directions and veloci- times that we’d already raised two underwater vehicle that can remain at sea ties, and reflections from particles in the children. Sometimes she didn’t enjoy for months. Scientists on shore can direct water, such as oil droplets. The glider was raising a fleet of gliders, another whole its movements via satellite phone. Lucky Eddy Deepwater Horizon FLORIDA CUBA MEXICO Background image from NASA The Loop Current typically At random times, the loop When that happens, the An eddy formed in early June flows up toward Louisiana. narrows at its southern end current flows more directly 2010, effectively blocking But three or four times a year, and pinches off a swirling through the Florida Straits, spilled oil from flowing up it temporarily loses its loop. circle of water called an eddy. bypassing most of the Gulf. the East Coast. WooDS hole oceanographic institution 7.