mixing, as obtained throughout the eastern part ol Chirikov 

 hasin, eontinues to modify these water masses from the south 

 as they traverse the southern Chukehi Sea. 



The relatively eold. sahne water that is not eoming from 

 the south is found in the eentrai and western parts of the 

 southern Chukehi Sea; in the Korolcv data the extreme \ alues 

 are from Stations 44 and 45, north of Koi\ uehin Bay on the 

 Siberian Coast (cf. Frontispiece). Current measurements 

 (Coachman & Shigaev. Subchapter 2. 1 . this \c)lume) indicated 

 this water was (lowing southeast, parallel with the Siberian 

 coast, the so-called Siberian Coa,stal Current, This current is 

 advecting the cold, high S water into the southern Chukehi Sea 

 from somewhere in the northwest, perhaps near Long Strait 

 (between Wrangel Island and the mainland). The flow did not, 

 however, continue southeast as far as Bering Strait; no water 

 with S>32.9 ppt was observed there. 



Thus, the Siberian Coastal Current separates from the 

 coast before reaching Bering Strait, and curves eastward into 

 the central part of the southern Chukchi Sea. Waters in the 

 middle of the region, midway between Alaska and Siberia 

 (Stations 47, 56). indicate considerable mixing has taken place 

 between this cold, saline water, and the core water of the 

 northward flow from Bering Strait that lies around the east and 

 north sides of the central region. The interaction has reduced 

 salinities of the Siberian Coastal water in the central region to 

 ~.^3 ppt and warmed the mass by I to 2°C. 



We note the situation in August 1988 is undoubtedly the 

 normal summer tlow pattern; however, under rare conditions it 

 appears that the Siberian Coastal Current can penetrate farther 

 southeast, as far as Bering Strait. Ratmanov (1937a) observed 

 cold, saline water near Cape Dezhneva in summer 1933. but it 

 was not moving southward through the strait. There is no 

 evidence that this water ever penetrates into the Chiriko\ basin. 



Summary of Modifications 



The quantitative changes in temperature and salinity 

 characteristics of the water masses as observed in August 1 988 

 are summarized in Table I . The changes are in characteristics 

 of the water layers below the surface layer, which are 

 conservative ( i.e., T and S values are altered by the processes 



of advection and diffusion only). The surface layer properties 

 are affected also by surface exchange; in summer they are 

 warmer and less saline than the deeper waters and much more 

 variable. 



Table I shows, in addition to the approximate T and S 

 change, the estimated distance over which the change has taken 

 place and the property value change per km. The latter statistic 

 gives an idea of the effectiveness of the mixing in that part of 

 the regime; comments list the major processes acting. 



The greatest changes in water mass properties take place 

 at the beginning, where the Bering Slope Current water crosses 

 the outer shelf on its way into the Gulf of Anadyr. Layering of 

 cold, less saline shelf water with warmer, more saline slope 

 water, followed by vertical mixing, are effective in reducing 

 S"s andT'sand. ultimately, creating the quite uniform Anadyr 

 water mass, which is advected on northward through Bering 

 Strait. The energy for the mixing is from shear in the Anadyr 

 Current, generated both laterally as the current circumnavigates 

 the gulf and vertically in the shoaling water columns. 



Across the Chirikov basin the major mixing is vertical; 

 this process is stronger on the east side in the shallower water. 

 Lateral mixing is small; there is essentially none in the west. 

 and it is small in the east, leading to small reductions in S of the 

 coastal water. These same processes continue to modify 

 Anadyr/Bering Shelf and Alaskan Coastal waters in the southern 

 Chukchi Sea at about the same rate. 



Siberian Coastal water, indigenous to the Chukchi Sea, 

 enters the southern part of the sea from the northwest, and then 

 apparently circulates in acyclonic gyre, interacting with Anadyr 

 water around its east and north sides. The interaction seems 

 moderately active and analagous with that in the Gulf of 

 Anadyr; first a layering and interleaving of the water masses 

 (densities differ by -0.5 st). followed by vertical mixing. 



We aeknowledge the helpof Margaret Lavender both in the field 

 and in data reduction. Captain O. A. Rostovstev and Chief Scientist. 

 Professor A. V. Tsyban. deserve special thanks, as does all the crew 

 of the Korotev. Viktor Shigaev was a great help in liaison and 

 interpretation, and the skill of hydrographic specialists Sergei and 

 Anatoly was much appreciated. The senior author is indebted to 

 Dr. R. S. Jones for allowing his participation in the cruise and for use 

 of the L'TMSl equipment aboard the Konilcv. This is Contribution 

 No. 777 of the Marine Science Institute. University of Texas. 



33 



