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Two cruises underway in August and September are using the U.S. Coast Guard Cutter Healy, a polar icebreaker with state-of-the-art research capabilities, to explore continental shelf areas and deep ocean basins in the Arctic Ocean. During the first cruise, August 14 to September 5, scientists on Healy employed a sophisticated echosounder to measure sea-floor depths (bathymetry) in an Arctic area known as the Chukchi Cap. During the second cruise, September 6 to October 1, Healy will be joined by the Canadian Coast Guard Ship Louis S. St-Laurent (Louis). Healy will collect more bathymetric data, while Louis collects seismic-reflection data to map the geology of the subseabed. The ships will take turns leading and breaking ice to maximize the quality of the data each collects.
"September's two-ship experiment will allow both the U.S. and Canada to collect and share complementary data in areas where data acquisition is costly, logistically difficult, and sometimes dangerous," said USGS scientist and project leader Debbie Hutchinson, who has been aboard Louis since it left port in late August. "Both countries benefit through sharing of resources and data, as well as increasing the likelihood of success by using two icebreakers in these remote areas of the Arctic Ocean."
"Healy uses a multibeam bathymetry system to map the sea floor," said USGS scientist Jonathan Childs, chief scientist on Healy during the September cruise. "Unlike conventional echosounders, which measure the water depth of a point directly beneath the ship, the multibeam system collects a 'swath' of depth information about 3 km wide along the ship's path. When the swaths are merged, they create a three-dimensional viewmuch like an aerial photographof the sea floor." Although its extensive continental shelves make the Arctic Ocean one of the shallowest ocean regions, with an average depth of approximately 1,200 m (4,000 ft), the water depths in the central Arctic Ocean are almost 4,000 m (more than 13,000 ft).
Data collected aboard Louis by scientists with the Geological Survey of Canada, a part of NRC, will be the first modern seismic-reflection data collected in the Beaufort Sea at these latitudes (76° to more than 80° N., depending on ice conditions).
Scientific staff on Healy will include not only USGS geologists and geophysicists but also ice researchers measuring and analyzing sea-ice conditions, biologists studying Arctic phytoplankton, and marine-mammal observers monitoring and reporting on the occurrence and behavior of polar bears, seals, walruses, and other Arctic mammals.
During the cruise, USGS staff on Healy will send updates about their activities and observationsincluding written descriptions, photographs, audio interviews, and video footageto the USGS Web site "Arctic Chronicles."
This research program is being conducted in collaboration with the National Oceanographic and Atmospheric Administration (NOAA) and University of New Hampshire's Joint Hydrographic Center, which led the August 14-September 5 cruise. The Arctic research is coordinated by the Extended Continental Shelf Task Force, a government-wide group headed by the U.S. Department of State, whose members include the USGS, NOAA, the Minerals Management Service, the Executive Office of the President, the Joint Chiefs of Staff, the U.S. Navy, the U.S. Coast Guard, the Department of Energy, the National Science Foundation, the Environmental Protection Agency, and the Arctic Research Commission.
Summer 2008 is the fourth summer that the United States has collected data in the Arctic in support of defining the limits of its extended continental shelf, where the United Nations Convention on the Law of the Sea allows coastal nations to exercise certain sovereign rights. The data, most of which will be released to the public, will also provide greater scientific insight into relatively unexplored regions of the ocean. Learn more about this multiyear effort visit, Defining the Limits of the U.S. Continental Shelf. Additional information about the September cruise is on the Scientists Map Unexplored Arctic Sea Floor Web page.
in this issue:
Scientists Map Arctic Sea Floor
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