Oceans and seas

Beaufort Sea

May 14, 2013, 1:24 pm

The Beaufort Sea is a marginal sea consisting of the waters off the northern coast of Alaska and Canada.

This is bounded to the east by Banks Island of the Canadian Arctic Archipelago and on the west by the Chukchi Sea.

The bathymetric characteristics include the narrowest continental shelf found anywhere in the Arctic Ocean. This shelf is dissected by three submarine valleys, the largest of which is 45 kilometers wide, and drops off rapidly to the Beaufort Deep, whose maximum depth is 3940 meters (m).

caption Source: Wikimedia Commons


Although it is geographically identified as a separate entity, the Beaufort Sea is oceanographically an integral part of the Arctic Ocean and as such cannot be described in isolation.
 

Hydrography

Substantially different circulation regimes are found on the inner and outer shelf regions, with the demarcation line corresponding approximately to the 50 m isobath. The inner shelf is strongly wind driven in summer, with a westward water motion driven by the prevailing easterly winds. This circulation varies seasonally, responding rapidly to large changes (including even an occasional reversal in prevailiing wind direction), and is far less energetic in the winter (with wind effects persisting even under the fast ice close to the shore). The outer shelf circulation is energetic at subtidal frequencies throughout the year, with the dominant feature being the Beaufort Undercurrent, a bathymetrically steered mean eastward flow extending from around the 50 m isobath to at least the base of the continental slope. This relatively strong current apparently increases with depth to around 10 centimeters per second (cm s−1), and is probably not locally driven but rather part of the large scale circulation in the Canadian Basin, although the portion of the Undercurrent overlying the shelf can be modified by local wind forcing. Frequent cross–shelf motions are found near the inshore edge of the Undercurrent, with daily means exceeding five cm/sec and durations typically three days or more. These serve to transport materials between the inner and outer shelf regions.

The most prominent hydrographic feature on the shelf is a subsurface summer temperature maximum generally found seaward of around 40–50 m depth which disappears during the winter. This is associated with an eastward flow of water originating in the Bering Sea. The warm water enters via the eastern Bering Strait and follows the Alaskan coast around Point Barrow. It is composed of two water masses called Alaskan Coastal Water (ACW) and Bering Sea Water (BSW). The ACW has summer temperatures of five to ten degrees Celsius  (C) west of Barrow with salinities less than 31.5. It mixes rapidly with local surface water as it moves eastward and is not clearly identifiable east of around 147 to 148 degrees W. The BSW is more saline and has a density range from 25.5–26.0 σt, and can be traced as far east as Barter Island at 143 degrees W.

See Also

Further Reading

  • Rhodes W. Fairbridge, editor. The Encyclopedia of Oceanography. Van Nostrand Reinhold Co., 1966.
  • Knut Aagaard. The Beaufort Undercurrent. In P. W. Barnes, D. M. Schell, and E. Reimnitz, editors, The Alaskan Beaufort Sea, pages 47–71. Academic Press, Inc., 1984.
Glossary

Citation

Baum, S. (2013). Beaufort Sea. Retrieved from http://www.eoearth.org/view/article/150457

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