Find Out More Information About Ice Age, Arctic Circulation Patterns
December 11, 2003
The cruise, led by Larry Mayer of UNH, demonstrated that an ice breaker could successfully map the seafloor with multibeam sonar while breaking ice. The U.S. Coast Guard Cutter Healy, a 420-foot multibeam sonar-equipped ice breaker, carried the scientists on the expedition. The scientists mapped 1,530 nautical miles of the 2,500-meter-depth contour of the continental slope north of Alaska as they accomplished the United States' first Law of the Sea ocean mapping surveys in the Arctic Ocean.
Article 76 of the UN Convention on the Law of the Sea provides a mechanism for nations to claim rights to their continental shelf and slope beyond their current EEZ limits. To support claims, nations must present, among other things, bathymetric data establishing the location of the 2,500-meter (about 8,200 feet) depth contour and the foot of the continental slope. The cruise demonstrated that an ice breaker ship could successfully map the seafloor with multi beam sonar while breaking ice. These features are best located with modern multi-beam sonar surveys. Though the United States has not ratified the convention, the U.S. is preparing to present and support a claim. The data compiled from the cruise will help support the claim and the jurisdiction the U.S. has over the seabed areas, thus giving the U.S. rights to potentially valuable natural resources.
Before the cruise, existing charts of the Arctic bottom showed only a small knoll where scientists discovered the complex seamount. The seamount abruptly rises more than 3,000 meters (about 9,850 feet) from the ocean floor to approximately 925 meters (3,035 feet) of depth. The cruise team also discovered water depths over 4,000 meters (13,125 feet), depths not previously measured anywhere in the Amerasian Basin of the Arctic Ocean.
The cruise also added important information about ice age glaciation and past climates. Randomly oriented seafloor scours, mapped at depths of 300-400 meters (980-1,310 feet) provide evidence of large icebergs scraping the seafloor. Parallel flutes, or grooves mapped at greater depths, provided clues to the motion of huge ice sheets creeping across what is today the continental shelf. A sediment core from the continental slope will provide improved insight into past periods of climate variability. Future cruises will complete the mapping of the 2,500-meter contour and the foot of the continental slope.
Additionally, the cruise obtained oceanographic data that will improve knowledge of the water masses and circulation in the Arctic. Kathy Crane of NOAA's Arctic Research Office led the physical oceanography effort, which successfully obtained temperature and salinity data at stations spread across the survey area. The NOAA/UNH cruise team also included scientists from the U.S. Naval Research Lab and the Navy's Arctic Submarine Lab, as well as guest scientists from Denmark and Sweden.
Data acquisition, processing, and analysis was provided by the NOAA/UNH Joint Hydrographic Center - UNH Center for Coastal and Ocean Mapping, which partners with NOAA's National Ocean Service. Ice breaker ship time was funded by NOAA's Office of Ocean Exploration, located in NOAA's Office of Oceanic and Atmospheric Research (OAR).
The U.S. mapping program for
the Law of the Sea began 18 months ago. The initial effort was
a study to determine the availability of existing data for Law
of the Sea purposes, and to identify where additional mapping
would be required. The project goal is to provide the evidence
needed to extend U.S. jurisdiction beyond the recognized 200-nautical-mile
limit of the United States' Exclusive Economic Zone (EEZ), an
area that contains mineral, oil, gas and fisheries resources
found on and below the sea floor.
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