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4 Physical Environment
Pages 67-86

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From page 67...
... lease-sale areas in Alaska: the area in the Navaho Basin portion of the Bering Sea and the two in the Chukchi and Beautort seas (see Figure I-. (Although this report focuses much more on the Chukchi and Beaulort lease areas Han it does on the Navann Basin, He Bering Sea is important because it interacts with the Chukchi Sea and, to a lesser extent, with the Beaufort Sea.)
From page 68...
... It is possible, at any given time, for one or both of these ships to be deployed in the Antarctic or in the Atlantic sector of the Arctic and to be unavailable for help in the Alaskan OCS. A possible tempering consideration is that the United States and Russia have an agreement for mutual aid in case of an of} spill; the Soviet Union offered assistance after Me Exxon Vaklez spill in Prince William Sound.
From page 69...
... Should a spill occur, the ice, as well as the currents in the region of these sites, will carry spilled oil. The Chukchi and Beaufort seas are off the north coast of Alaska in the Arctic Ocean proper; the Bering Sea is subarctic, located between Siberia and Alaska soup of the Bering Strait and north of the Aleutian Island chain.
From page 70...
... Matthew, Nun~vak, and the Pribilof islands are in the eastern Bering Sea shelf. The climate and weather of this high-latitude region are strongly related to the presence arm fluctuations of sea ice (Overland, 1981)
From page 71...
... Beaufort Sea, and the Mackenzie River in Be Canadian Beautort Sea. There are a number of smaller rivers such as Be Kobuk and Noatak that empty into the Chukchi and Beautort seas.
From page 72...
... , there are three identifiable water masses and related fronts. The water masses are related but not identical to He water masses in the soudleastern Bering Sea (Coachman, 1986; Hansell et al., 1989~.
From page 73...
... Some of this water goes Trough the Herald Canyon into He Arctic Ocean to He west of Herald Shoal, and some turns eastward as Bering Sea water that flows eastward along the outer shelf of the Beaufort Sea (Coachman et al., 1975; Aagaard, 1984~. In the eastern Chukchi Sea, Alaska coastal water also flows along He Alaska coast, gaining fresher, cooler water from He large rivers that empty into Kotzebue Sound.
From page 74...
... This major mountain range affects winds over much of Be Beaufort Sea coast (Kozo, 1984~. For example, near Barter Island, orographic modification of the winds can cause wind speeds 50% greater than that of the geostrophic wind (the wind resulting from a balance between horizontal pressure gradients and the Earth's rotation)
From page 75...
... Finally, wintertime atmospheric temperature inversions are common in the Arctic. They cause strong atmospheric surface stability that leads to diminished vertical turbulent exchange and hence to reduced wind stress on Be surface to drive ice and ocean circulation.
From page 76...
... Upwelling appears to be connected wig eastward-traveling wavelike disturbances in Be velocity records wig vertical displacements of about 150m. Condoning farther offshore of He Beaufort Undercurrent into Be Arctic Ocean, Be surface current and ice flow are characterized by a mean westward movement of ice and water at Be outer edge of Be anticyclonic Arctic Ocean gyre.
From page 77...
... , which are predictable from summer to summer. Finally, winter conditions in the Chukchi and Beautort seas produce fast ice along Be coast that interacts with the offshore open Arctic Ocean current and wind-driven free-floating sea ice to cause an extensive, somewhat predictable, system of flaw leads and polynyas off the Chukchi and Beautort coasts eastward to Be Canadian Archipelago.
From page 78...
... In the Beautort Sea, fast ice is more extensive because of protective barrier islands and because the grounded pileups of sea ice on the shelf act like small barrier islands. However, the fast ice in the Beaufort Sea is seasonal, usually lasting from November through June.
From page 79...
... The Bering Sea ice cover is almost entirely first-year ice; north of Bering Strait, the ice is 25-75% second-year ice or older. The older ice is thicker, with a mean of roughly 4 m.
From page 80...
... trajectory predictions must be tied more closely to observations Man has been Be practice. The committee also notes dlat GCMs for Be Alaska region have been used by several different contractors using different models, with little effort to synthesize the various results or to reconcile Be predictions with the limited existing observational data.
From page 81...
... The absence of information related to mesoscale variability in Me lease-sale areas is not seen as a flaw in the existing EIS, but that information will be required once specific production areas are identified. Studies should be designed to determine the spatial structure of Me wind field on scales of a few ldlometers in areas of production, with emphasis on the mechanics of the marine boundary layer and the interaction between the layer and coastal topography.
From page 82...
... Although these efforts have in many cases been quite successful, the number of observations available to describe the circulation in this vast area is much smaller than it is for other OCS areas bordering Be continental United States. Important distinctions also exist between the three lease areas: The Bering Sea, in which Be Navarin Basin is located, is the area for which the richest base of observations is available; less information is available for the Chukchi Sea, and Be greatest uncertainties concern Be U.S.
From page 83...
... Cat is discovered in Be region and as understanding of Me physical oceanic conditions improves. T~SMISS10~ OF POISE 1~ THE M~121~ ~VI~O~MI AT The effect of noise on marine mammals especially bowhead whales is a critical issue on the Norm Slope because Alaska Nadves depend on whales for subsistence.
From page 84...
... The committee also notes that the GCMs for the Alaska region have been prepared by different contractors using different models, with little effort to synthesize the various results or to reconcile the predictions with the limited existing observational data. Recommendation 2a: Conduct site-speci~c circulation st~ies In areas identified for production and in "hot spots" - reedling, feeding, arm aggregation areasidentifiedl by biologists and Alaska Natives with long experience in debug with the physical environment.
From page 85...
... Recommendation 2b: Refine existing models for use at sites selected for exploration Carl development ares at biological "hot spots." Coordinate modeling with observations in the same area. Little progress can be expected from refining existing large-scale models.
From page 86...
... Altemative: None recommended. Conclusion 3: It is well understood that the atmosphere influences ocean circulation in OCS areas, in part because of the local effect of wind stress and heat transport, but also farther away as conditions in distant areas are propagated through the coastal ocean by pressure gradients.


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