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Page 1 | Page 2 | Page 3 | Page 4 THE NEXT LEVELArgo is the name of an array of floats spread out over the world's oceans. It was conceived as a more sophisticated successor to the World Ocean Circulation Experiment (WOCE), which, for the better part of the 1990s, broke ground in its use of autonomous floats to track ocean currents. Argo was designed to measure more water properties than WOCE floats and, more importantly, to have an indefinite run. Scientists named it after the vessel from Greek mythology; its counterpart satellite is named Jason. When depicted on animated maps, the Argo armada takes on the appearance of having spread like an epidemic since Australian researchers deployed the first half-dozen floats in 1999. The floats are dropped from ships and the backs of aircraft and begin recording data autonomously as soon as they hit the water. They continue to do so as long as their batteries last, usually about four to five years. About 30 percent of the floats, called Sounding Oceanographic Lagrangian Observer (SOLO) instruments, are based on a design co-invented by Scripps research oceanographer Russ Davis, whose breakthroughs in instrument development helped make WOCE possible 20 years ago. Most SOLO floats are still made at Scripps. The rest of the array is filled by floats designed either by a private American firm or a French research agency. Each tube-shaped float descends to depths up to 1,800 meters (6,000 feet), drifts on ocean currents for 10 days, then returns to the surface when oil is pumped to an external bladder on the bottom of the instrument. At the surface, the float beams results to a passing satellite. The profile of ocean conditions they generate is then processed and posted within 24 hours of transmission. The raw temperature and salinity data as well as the position of the floats relative to where they were during their last contact with the satellite allow for a wide range of interpretive study.  
New floats added to the array have improved the resolution of its dataset the way additional pixels sharpen the image on a television screen. The challenge for the Argo steering team, an international committee co-chaired by Scripps physical oceanographer Dean Roemmich, has been to add new floats faster than old ones wear out. In some cases, they experience other unanticipated service disruptions. Earlier this year, for example, satellites tracked one wayward unit making measurements on land. It turned out that the unit was dutifully measuring temperature and salinity levels on the streets of downtown Brisbane, Australia. The unit was touring the city in the bed of a pickup truck owned by the fisherman who had trawled it from the seafloor just off the coast. The angler planned to convert it into a fashionable mailbox. In 2004, when Argo reached its halfway point, there were enough floats operational to allow the network to offer what could be considered worldwide coverage, a hazy view of things to come. Next page: Live from the eye of the storm |
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