by Mariette DiChristina
If you want to know the weather for the next few days, look up at the clouds. But for trends over the next few decades, you'll have to turn to ocean currents, especially those deep beneath the surface. "These currents distribute the heat absorbed from sunlight around the globe," says Russ Davis, a physical oceanographer at the Scripps Institution of Oceanography in La Jolla, Calif. If scientists could map the currents, they could better understand the complex interactions between ocean and atmosphere. However, salaries and equipment for a team of shipboard scientists tracking probes can run $30,000 a day. ALACE, the brainchild of Davis and his colleagues, is a better solution.
Short for Autonomous Lagrangian Circulation Explorer, ALACE is a torpedo-shaped aluminum robot dropped by the dozens into the seas. Each ALACE sinks to 1,000 meters (about 3,300 feet), where it bobs in the currents. About once a month, the robot surfaces to give data on temperatures and salinity, and to transmit its current location to weather satellites. ALACEs last about 70 cycles (of about 25 days each), and cost just $10,000 apiece.There are now about 325 ALACEs in the Pacific, Atlantic, and Indian oceans. They've even drifted into the iceberg-laden Antarctic. "ALACEs operate for Earth the way interplanetary probes work," says Davis. "They're off doing amazing explorations in places where we can't conceive of being."The ALACEs' wanderings will form part of the World Ocean Circulation Experiment, a multiyear international effort that is exploring the link between oceans and climate.
Ocean Planet Exhibition Floorplan
gene carl feldman (gene@seawifs.gsfc.nasa.gov) (301) 286-9428