Oceanography 



Oceanographic investigation of the Beaufort 

 Sea from surface vessels has been limited to the 

 coastal fringes owing to the presence of ice the 

 year-around in the offshore areas. In favorable 

 summers, large areas of open water appear along 

 the north slope coast, particularly from Herschel 

 Island (139°W) northeastward (U.S. Navy Hy- 

 drographic Office, 1956). These large ice free 

 areas are most likely the result of relatively warm 

 river overflow from the North American mainland 

 melting the sea ice (Sater, 1969). The physical 

 properties of the open water areas are fairly well 

 defined (U.S. Navy Hydrographic Office, 1954, 

 1956, 1963; Marine Science Center, 1968). 



Investigation of the ice-covered deep Basin of 

 the Beaufort Sea has been primarily from drifting 

 ice stations (Flectcher's Ice Island, T-3; Arlis I 

 and II; and Russian drifting stations). Some data 

 has been collected by aircraft ice landings (Ski- 

 jump 1 and II). 



Results of all the data from the Beaufort Sea 

 reveal three major water masses: Arctic Water 

 (0-200 m); Atlantic Water (200-900 m); and Arc- 

 tic Bottom Water (900 m-bottom). These water 

 masses generally fit the classical description by 

 Nansen (1902) with some qualification due to 

 local climatological fluctuations, advections, and 

 mixing. These factors are reflected in the broad 

 range of temperatures (at or near the freezing 

 point to 3.0°C) and salinities (3.0 to 32.0°/oo) 

 reported for the surface layer (0-40 m) in the 

 summer and for the lower temperatures in the core 

 (0.3-0.5°) of the Atlantic layer. 



Sverdrup (1956) estimated that about two me- 

 ters of ice is formed in the Artie in the winter with 

 about one meter of ice melting in the summer. He 

 assumed that the difference between ice forma- 

 tion during the winter and icemelt in the summer 

 is compensated by net drift of ice out of the 

 region. This assumption may not hold for the 

 western Beaufort Sea because of irregular cur- 

 rents, unknown amounts of fast ice along the 

 coast, variable winds, and variation in heat from 

 river runoff. However, the irregular presence of 

 icemelt will cause variation in the surface tem- 

 perature and salinity. Sater (1969) indicated that 

 in the northern Beaufort Sea icemelt can mix to 

 some extent with the underlying sea water through 



differential movement of ice and by wind mixing 

 in ice-free areas, but icemelt rarely decreases the 

 surface salinity to below 28.0°/oo. 



In the southern Beaufort Sea, river runoff be- 

 comes an important factor affecting the surface 

 temperature and salinity, especially between May 

 and October. This area is characterized by a 

 broad (avg. 40 km), shallow continental shelf 

 (less than 65 m) having a large surface area in 

 relation to its total volume. The combined river 

 iTjnoff received by this area with its large surface 

 to volume ratio influences surface water condi- 

 tions in the sea. Antonov (1958) estimates that the 

 land drainage of North America flowing into the 

 Arctic excluding the Yukon River is 813 km^/yr. 

 (The drainage of the Yukon is estimated to be 240 

 km^/yr. However, most of this water becomes 

 mixed with Pacific water to form a major part of 

 the Alaskan Coastal Current in the northern Ber- 

 ing Sea and Chukchi Sea (Saur et al., 1954), and 

 in this paper it will be considered as a component 

 of the total flow through the Bering Strait entering 

 the Arctic). Along the continental shelf of the 

 North Slope, river runoff together with icemelt 

 can cause surface water temperatures as high as 

 3.0°C and surface salinities as low as 3.0°/oo. 



The influence of Pacific water on the charac- 

 teristics of Arctic Water in the Beaufort Sea 

 seems to be threefold: a subsurface temperature 

 maximum (75 m), a minimum (160 m) and a near 

 surface temperature maximum. Coachman and 

 Barnes (1961) found a subsurface temperature 

 maximum at 75-100 meters depth in the Beaufort 

 Sea and attributed its existence to advection of 

 Pacific water through the Bering Strait. The 

 temperature maximum is best developed due 

 north of the Chukchi Sea and decreases in tem- 

 perature as it travels around the Beaufort Sea 

 anticyclonic gyre. 



A thin layer exists at about 160 meters in 

 ArcticWater that is characterized by a tempera- 

 ture minimum (—1.4 to — 1.5°C) and a nutrient 

 maximum (P04> 1.8 Mg-at/l, NO3 > 17 

 )U.g-at/l). Kinney et al. (1970) suggest that this 

 layer is due to Bering Sea winter water. 



Intrusion of relatively warm (>0°C) Pacific 

 water in the shelf waters of the western Beaufort 

 Sea has been reported (Johnson, 1956). This 

 water is 2 to 4°C warmer than the Pacific water at 



