Physical Oceanography of the Western Beaufort Sea 



By 



Gary L. Hufford, Scott H. Fortier, Daniel E. Wolfe, 

 James F. Doster, and Dennis L. Noble^ 



GENERAL DESCRIPTION OF STUDY AREA 



Geography 



The Beaufort Sea is the traditional name ap- 

 plied to the waters off the northern coasts of 

 Alaska and Canada. It is an integral part of the 

 Arctic Ocean and cannot be separated oceano- 

 graphically. The Beaufort Sea extends from the 

 Chukchi Sea on the west, to Banks Island of the 

 Canadian Archipelago on the east. The northern 

 limits are arbitrarily set as a line drawn from Point 

 BaiTow, Alaska to Cape Lands End in the Cana- 

 dian Archipelago. The southern portion of the Sea 

 overlies the continental shelf off the northern 

 coasts of Alaska and Canada, which extends 

 northward approximately 150 kilometers, and is 

 generally shallower than 65 meters. It then drops 

 off rapidly into the Canadian Basin, reaching a 

 depth of 3940 meters in the Beaufort Deep (Fair- 

 bridge, 1966). 



The coastal plain bordering the Beaufort Sea on 

 the south, collectively with the foothills of the 

 Brooks Range, is known as the Arctic Slope, or 

 more commonly as the North Slope. Permafrost in 

 this region penetrates the ground to a depth of 

 1100 feet (Thoren, 1959). The bordering coastal 

 area has 6 rivers draining the North Slope into the 

 Beaufort Sea. Antonov (1958) has estimated the 

 total flow from these rivers to be 813 km^/yr with 

 greatest drainage occurring between May and Oc- 

 tober. The Mackenzie River (137°W) accounts for 



'U.S. Coast Guard Oceanographic Unit. Bldg. 159-E, Washington Navy 

 Yard, Washington, D.C. 20390. 



nearly 50% (430 km^/yr) of the total flow. Along 

 the coast of the North Slope exist many low gravel 

 islands which constantly shift as the result of 

 wave and ice action. 



The Western Beaufort Sea Ecological Cruise 

 (WEBSEC-71 and 72) surveys covered the south- 

 ern portion of the Beaufort Sea from just east of 

 Point Barrow (155°W) to Barter Island (143°W) 

 extending northward to the 2000 meter isobath 



(fig- !)• 



Ice 



Investigations of the Beaufort Sea have been 

 hampered by a heavy year-round covering of 

 winter ice in offshore areas which may be grouped 

 into two major categories: multi-year ice and 

 first-year ice. Multi-year ice is ice that has sur- 

 vived the summer melt. It is usually fresher and 

 stronger than first year ice. First-year ice forms in 

 the many openings (polynyas, fractures, and 

 cracks) which are scattered throughout the polar 

 pack, as well as on open water found along the 

 coast. This ice may be fragmented by the action of 

 winds and surface currents to produce openings of 

 various sizes. In addition, stresses on the pack ice 

 can form pressure ridges that may exceed 30 feet 

 in height when first formed. Along the coast these 

 pressure ridges may exceed 40 feet or more with 

 on-shore winds. (U.S. Navy Hydrographic Office, 

 1968). 



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