As the Gulf oil spill approaches its third month, researchers are using a relatively new tool to track the plume: "glider" robots that use water power to zigzag through the ocean.

Eight of these robots are now prowling the Gulf, driven remotely by researchers from institutions across the country. The gliders carry sensors to measure everything from water temperature to organic material that could mark the presence of dissolved oil.

The idea, said Rutgers University oceanographer Oscar Schofield, one of the collaborators on the effort, is to track the spill and provide data on ocean movement to improve predictions of where the oil will go next.

"These gliders are collecting physical data that’s helping keep the models on track, so they’re helping improve the ocean forecast," Schofield told TechNewsDaily.

The gliders look like torpedoes with wings. They move by sucking in seawater, which causes them to tip forward and sink. When the glider reaches the desired depth, it expels the water, causing it to tip back toward the surface. The cycle, controlled by a driver hundreds of miles away in a laboratory, propels the glider forward in a saw tooth pattern. This low-energy propulsion means that batteries that could run a propeller for mere days can keep the glider going for months.

Each glider carries sensors to measure ocean properties like temperature and salinity. That data can be entered into models to predict the movements of ocean currents — and of the spreading oil slicks.

Other sensors sample the water chemistry in an effort to measure the effects of the spill. Chlorophyll detectors measure plankton blooms, and a device called a flourometer measures colored dissolved organic material, which can include oil. Each time the gliders surface, they beam this data back to researchers in the lab.

The gliders in the Gulf launched in late May, and are currently off the coasts of Florida and Louisiana. A map of the robot’s real-time location is available at rucool.marine.rutgers.edu/deepwater, along with the data collected.

The Rutgers team is driving two of the eight gliders; the rest are controlled by researchers at Scripps Institution of Oceanography in San Diego, the University of Delaware, the Mote Marine Laboratory in Florida, the U.S. Navy and the private company iRobot.

Gliders were rare just five years ago, said Schofield, but they’ve become popular tools for research in the harsh conditions of the Antarctic, where the deployment of research vessels is difficult. In the Gulf, researchers continue to use data from ship-based monitoring, but the gliders are quicker and more maneuverable, Schofield said.

"The robots can provide a bigger spatial map to complement what the ships are doing," he said. "They’re really a supporting tool, but they can be out there in all conditions, all the time."