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Navy sub mapping Arctic Ocean seafloor

By Environmental News Network staff

Web posted Wednesday, July 1, 1998
at 10:55 AM ET


The USS Hawkbill 666 leaves port June 1 on its mapping mission in the Arctic .
(ENN) -- A U.S. Navy nuclear-powered submarine has embarked on a 75-day cruise to map the seafloor of the Arctic Ocean. The sub has been fitted with a civilian sonar system that will provide scientists with three-dimensional images of the unmapped region.

The sonars, known together as the Seafloor Characterization and Mapping Pods, have been mounted on the underside of the USS Hawkbill, which is en route to the Arctic for the Navy's fourth annual unclassified science cruise.

Dale Chayes and Jay Ardai, both of Columbia University's Lamont-Doherty Earth Observatory, Palisades, N.Y., will operate the sonars and oversee acquisition of geophysical data during the cruise.

"We can now do mapping in the Arctic that has never been done before," said Chayes, who has spent several years developing SCAMP in anticipation of the cruise. "The sub can go farther and faster under the ice than any icebreakers can go through it. And because the sub is so much quieter and more stable, we can get much higher quality sonar data that will reveal a picture of the Arctic seafloor that we have never had before."

SCMAP is made of two sonar mapping systems designed to take advantage of the submarine's unique characteristics. One is a swath mapping system, which measures seafloor depths across a zone extending up to about six miles on either side of the advancing submarine. These measurements can be stitched together to create continuous, large-scale maps of the ocean floor. The swath mapping system also collects backscatter data, which illuminates seafloor textures such as scarps and lava flows. SCAMP's other sonar is a sub-bottom profiling system that will profile structures down to about 100 meters below the seafloor.

Lamont geophysicists will use SCAMP data to obtain 3-D images of seafloor features, such as the Gakkel Ridge, a spreading center between North American and Eurasian tectonic plates where new seafloor is created. "Data collected will help us to understand how oceanic crust is formed at spreading centers and the processes by which magma is brought to the surface," said Dr. James Cochran.

The SCAMP system attached to the sub will allow scientists to "collect data like mowing the lawn," said Dr. Bernard Coakley, who took part in the first two Scientific Ice Expedition cruises in 1993 and 1995.

The Hawkbill will also collect water samples, which will be used by two Lamont geochemists, William Smethie and Peter Schlosser, to study Arctic Ocean circulation.

The Arctic Ocean plays an important, but still poorly understood, role in regulating the Earth's climate. Smethie uses chlorofluorocarbons and Schlosser uses isotopes of hydrogen and helium to trace the direction and speed of waters circulating through the ocean.

Copyright 1998, Environmental News Network, All Rights Reserved


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