water masses mixed to form Antarctic Bottom 

 Water. These were the cold (<-1.9° C.) saline 

 (>34.60o/oo) water which was found on the con- 

 tinental shelf below about 200 meters and the 

 Warm Deep Layer (>0.2° C. and >34.67o/oo, 

 based on IWSOE data) which was found from 

 about 500 to 1000 meters depth off the shelf 

 (Sections B and C). These two water masses 

 met at the upper part of the continental slope. 

 Seaward of the continental shelf, mixing and 

 sinking of dense shelf water and Warm Deep 

 Layer water are clearly indicated. Sections A, 

 B and C (fig. 4-15) show this, particularly in 

 the vicinity of stations 18 and 25. Further 

 mixing at depth is also made apparent by 

 the sigma-t distributions. The 27.85 and 27.86 

 isopycnals plotted on the temperature cross 

 sections illustrate this (figs. 4, 8, 12 and 16) as 

 do the isentropic analyses of the temperature 

 distribution on the 27.85 and 27.86 sigma-t 

 surfaces. 



The primary conclusion reached as a result 

 of the data analyses is that water of sufficient 

 density to mix with the Warm Deep Layer 

 and form Antarctic Bottom Water was being 

 formed during the austral summer in the 



Southwestern Weddell Sea. The data indicate 

 that this dense shelf water was not formed at 

 the air-sea interface nor was it formed else- 

 where and transported into the Southwestern 

 Weddell Sea area. Its presence during the sum- 

 mer can not be explained as winter-formed 

 water entrapped by bottom topography since 

 the area is quite flat and can not prevent water 

 from flowing off the shelf (fig. 24). Conse- 

 quently, it is concluded that the most logical 

 method of formation is the mechanism de- 

 scribed by Lusquinos (1963). This method of 

 formation requires that the dense shelf water 

 attain its temperature-salinity characteristics 

 by interaction with the extensive ice shelf in 

 the Southwestern Weddell Sea. The tempera- 

 ture of the water is reduced, the salinity is 

 increased due to freezing and the density of 

 the water is therefore increased. Thus the cold 

 dense shelf water is formed on a continuous 

 basis and subsequently mixes with warm deep 

 water to form Antarctic Bottom Water. 



These data as well as additional data col- 

 lected during IWSOE '69 are presently being 

 analysed in detail and the results will be pub- 

 lished in the near future. 



References 



Defant, Albert (1961) Page 150 In: Physical Oceanog- 

 raphy, Pergammon Press, New York, 1, 729 pp. 



Dietrich, Gunter (1963) Pages 477-480 In: General 

 Oceanography, John Wiley and Sons, New York, 568 



pp. 



Hollister, Charles D. and Robert B. Elder (1969) Con- 

 tour Currents in the Weddell Sea, Deep Sea Research, 

 16, 99-101. 



Klepikov, V. V. (1963) Weddell Sea Hydrology, Trudy 

 Soverskoy Antarkticheskoy EkspeditsU, Gidrologiya 

 Pribrezhnykh Antarkticheskikh Vod (works of the 

 Soviet Antarctic Expedition, Hydrology of Antarctic 

 waters), 17, 45-93, Leningrad, Morskoy Transport 

 Publishing House. 



Kvinge, Thor (1968) Technical report on project to 

 measure currents related to the formation of Ant- 

 arctic Bottom Water in the Weddell Sea, Geof. Inst. 

 Univ. Bergen, 19 pp. 



Lusquinos, A. J. (1963) Extreme temperature in the 

 Weddell Sea, Mat. Naturv. Serie, Univ. Bergen, No. 



23, 19 pp. , „, 



Strickland, J. D. H. and J. R. Parsons (1955) A Man- 

 ual of Sea Water Analysis, Fisheries Research Board 

 of Canada, Bulletin No.l25, 203 pp. 

 Thorndike, E. M. (1959) Deep-sea cameras of the La- 

 mont Observatory, Deep Sea Research, 5, 234-237. 



