US/USSR BERING '88 

 CHIHIKOV + Anadyr S Bering Straits 



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30 31 32 33 



SALINITY (ppt) 



3a. All CTDdala{ 1-m average values) from the Chirikov basin, including 

 Anadyr and Bering Straits. 



warmer and less saline values (to the upper left in the T/S, 

 plane). Likewise, surface water values lie along the same 

 general trend line. When the spatial distribution of stations is 

 examined, we see that the colder, more saline water is associated 

 with stations from the west side of the basin, while the warmer, 

 least saline water is all on the eastern side. 



The Chirikov basin is a little shoaler on the east side, 30 m 

 grading downward to nearly 50 m off Siberia. The freshwater 

 sources to the water masses in the basin are essentially confined 

 to the eastern side — the Yukon River and other runoff from the 

 Alaskan coast. The freshwater generates layering in the water 

 masses of the eastern portion of the basin, and together with the 

 shorter water columns, seasonal insolation is very effective in 

 warming, producing temperaures up to 1 2°C in the upper layer 

 (in contrast with maxima of ~8°C in the Gulf of Anadyr). 



The coldest, most saline water is water of the Anadyr 

 Current entering through the Strait of Anadyr (see above), and 

 also shelf water from south of St. Lawrence Island (cold, 

 relatively saline shelf water is probably also entering the basin 

 around the eastern end of St. Lawrence, through the west side 

 of Shpanberg Strait, but the A^o/'o/ev data do not cover Shpanberg 

 Strait). 



To illustrate quantitatively the modifications occurring in 

 the basin. Fig. 3b plots key stations. There is a salinity gradient 

 of more than one-half ppt across Anadyr Strait. The most saline 

 water is from the Anadyr Current (Station 39. cf. Fig. 2b). On 

 the east side (Stations 42, 43), though, the waters are both less 

 saline and colder — this is shelfwaterfrom south of St. Lawrence 

 Island, which is originally Bering Slope water that has been in 

 residence on the huge shelf south of St. Lawrence where it has 

 become diluted to a small degree by a freshwater admixture 

 from the Alaskan Coastal water (see Coachman & Shigaev. 

 Subchapter2.1. this volume) and further modified in winter by 

 products from freezing activity in the perennial polynya south 

 of St. Lawrence ( Schumacher el al. . 1983). This is the origin 



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VBERING STRAIT 

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179 



CHIRIKOV BASIN 



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SOUTHWEST 

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33 



SALINITY 



Fig. 3b. T/S diagram of key stations from the Chirikov basin, illustrating the 

 major water mass modifications therein. No change in salinity of the 

 water on the western side indicates no lateral mixing; only deeper 

 temperatures are raised through vertical mi.xing. On the east, small 

 lateral as well as vertical mixing makes Alaskan Coastal water less 

 saline, warmer, and a little less dense. 



also of the "cold center" water. The flow through the eastern 

 part of Anadyr Strait is of this shelf water mass, not pure 

 Anadyr water, giving rise to the cross-strait gradient in salinity. 



The three stations across the western channel of Bering 

 Strait, Stations 76 on the west to 78 near large Diomede Island, 

 illustrate the characteristics ofthese water masses after transiting 

 Chirikov basin. The cross-strait salinity gradient is precisely 

 the same as in Anadyr Strait, only the waters have wanned — 

 minimum temperatures are now about 1.5°C instead of <0°C. 

 We can interpret that modification of the water masses flowing 

 northward through the middle and western part of the basin 

 includes no significant lateral mixing — there is no evidence of 

 any interaction between adjacent water masses within the flow, 

 nor any reduction in salinities by admixtures of Siberian 

 Coastal runoff on the west or fresher Alaskan Coastal water on 

 the east. The only significant mixing is vertically in the water 

 columns, which by mixing down warmer surface water has 

 raised bottom temperatures by ~\°C. 



Alaskan Coastal water on the east side of the basin, not as 

 well covered by Korolev data, is illustrated by Station 102 

 taken about halfway between Nome and St. Lawrence Island 

 (see Fig. 1 ). This water is the warmest and least saline of the 

 water masses, and the closer to the Alaskan coast, the warmer 



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