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06 December 2002                                      FOR IMMEDIATE RELEASE

Exploring an ice-bound world

SAN FRANCISCO—A new autonomous underwater vehicle (AUV) has provided scientists with a unique view beneath the Earth’s Arctic ice cap, helping shed new light on ocean circulation and global warming processes. Researchers from the Monterey Bay Aquarium Research Institute (MBARI), NOAA’s Pacific Marine Environmental Laboratory, and Scientific Solutions Incorporated will describe field trials of the AUV this week at the American Geophysical Union 2002 Fall Meeting in San Francisco.

In development since 1998, the ALTEX (Atlantic Layer Tracking Experiment) AUV had its first Arctic field trials during October 2001, venturing beneath the Arctic ice to within seven degrees of the North Pole. Launched from the U.S. Coast Guard icebreaker Healy in frigid temperatures and howling winds, the AUV received no instructions from outside but relied entirely on its internal computer to navigate beneath the ice, take oceanographic measurements, and eventually find its way back to the ship.


Launching the ALTEX AUV in Arctic seas

Despite sometimes harsh weather, this month-long cruise proved that the ALTEX AUV could be safely and reliably launched and recovered from small leads in the Arctic ice, and could successfully gather useful scientific information from beneath the ice itself. During its explorations the AUV traveled as deep as 500 meters, continually measuring temperature, salinity, oxygen and nitrate concentrations in the seawater, as well as the thickness of the surface ice overhead.

The AUV’s oceanographic data were checked against analyses of water samples taken using traditional sampling methods, such as Niskin bottles and CTD (conductivity-temperature-depth) casts. The combined results yielded unique, detailed information about a layer of relatively warm water that flows from the Atlantic into the Arctic Ocean. This flow has apparently increased in recent years and may be a sensitive indicator of global warming. Similarly the data on sea ice thickness were compared with earlier data collected by military submarines which suggest that Arctic ice has been thinning over the past two decades.

Many engineering challenges had to be overcome to operate an AUV in the Arctic. For example, simply navigating in polar regions can be very difficult because the Earth’s magnetic field is not a reliable direction indicator. MBARI engineers addressed this problem by combining an inertial navigation system with Doppler sonar measurements of the AUV’s movement relative to the surface ice pack.

MBARI scientists and engineers hope to return to the Arctic as soon as possible to continue their explorations. The current version of the ALTEX AUV has a range of 50 kilometers using metal hydride batteries. However future models may be able to travel 10 to 20 times this far using modified fuel cells currently in development. They may also be able to dive as deep as 4,500 meters, allowing scientists to collect data across the breadth and depth of the Arctic Ocean. Another AUV feature still in development is the ability to “phone home” by releasing buoys that float upward, melt through the surface ice, and then broadcast the AUV’s position and scientific data back to the laboratory via satellite.

The ALTEX AUV research received funding from the National Science Foundation and the Office of Naval Research.

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Media Contact: 
Debbie Meyer, AGU Press Room Dec. 6-10 (415) 905-1007
or at MBARI ( 831) 775-1807, pressroom@mbari.org

More images of the ALTEX AUV