liaison aboard the Louis and head of the U.S. David Mosher of Natural Resources Canada, Geological Survey of Canada, is leading the Canadian part of the mission. Brian Edwards, USGS, is chief scientist of the expedition aboard the Healy. Geological Survey (USGS), with additional funding and scientific support from the U.S. part of the mission is being led by the U.S. Marine mammal observers are also aboard, recording mammal sightings in areas where observations are rarely made and alerting the ship's officers when a mammal is close enough that operations should be adjusted in order to avoid disturbing it. As in previous years, ice extent and characteristics are being recorded, and (as conditions permit) open-ocean and ice buoys are being deployed to track water currents and ice movement. New to this year's project is a subsidiary study of ocean acidification, in which seawater samples are being collected and analyzed to examine the effect of increasing levels of atmospheric CO2 on arctic waters. Higher frequencies provide greater resolution but less penetration below the sea floor lower frequencies yield deeper penetration but less resolution. The frequency and energy of the acoustic signals, produced by sound sources (either mounted on or towed behind the vessel), determine how deeply the sound will penetrate beneath the seafloor and how much resolution (detail) will be revealed in the resulting images. Examples of such surfaces are the boundary between water and sediment (the seafloor) and the boundaries between rock or sediment layers of different types. The surveying systems on both ships rely on acoustic (sound) signals that bounce off surfaces, separating materials of different acoustic impedance - the product of the speed of sound in the material multiplied by its density. Image courtesy of Helen Gibbons, USGS/ECS Project. The two ships use a multibeam echosounder to map swaths of seafloor, which is then compiled to the onboard Map Server. Where heavy ice makes towing the seismic equipment unsafe, or in areas where multibeam bathymetric (water depth) data have scientific priority, the Louis breaks ice ahead of the Healy. In light to moderate ice, the Healy leads and breaks ice so that the Louis can tow its seismic gear. St-Laurent) and multibeam echosounder data (handled by those aboard the Healy). The primary goal is to collect both multichannel seismic data (which will be done by explorers aboard the Louis S. The 2010 survey is a two-ship expedition. This will be the first joint expedition to image sub-seafloor sediment layers within 200 nautical miles (nm) of the coast in the Arctic Ocean. The 2010 survey is taking place primarily in the Canada Basin of the Arctic Ocean, in an area bounded approximately by latitudes 71°N to 85°N and longitudes 158°W to 112°W ( see trackline map above). "EEZ" stands for Exclusive Economic Zone, which extends from a nation's coastline out 200 nautical miles (or to a maritime boundary with another nation). Planned tracklines for the 2010 U.S.-Canada Extended Continental Shelf survey. (Note that this legal definition of continental shelf is different from that traditionally used by marine geologists.) A Two-Ship Expedition However, the continental shelf of a coastal country extends beyond 200 nm (and is called, therefore, the “extended continental shelf”) if it meets criteria outlined in Article 76 of the Convention. Convention on the Law of the Sea, every coastal country has a continental shelf out to 200 nautical miles (nm) from its coastal baselines, or to a maritime boundary with another coastal country. Under international law, as reflected in the U.N. The data was used to determine the limits of the “extended continental shelf.” Previous joint missions were conducted in 20. and Canadian scientists are working together to map areas of the seafloor and to image the underlying sediment layers. cruises to the Arctic Ocean and the third in which U.S. The ASB was lowered by crane from Healy’s 02 deck to a spot level with the 01 deck, where the crew-a coxswain (the driver), crewman, small-boat engineer, and additional Coasties learning these positions-climbed aboard. Diversity, Equity, Inclusion, and Accessibility.
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