South Atlantic Oceans, Vertical sections of water temperatures based on 

 half -hourly BT observations across the convergence and horizontal plots 

 of air temperature plus surface water temperatvire, salinity, and density 

 obtained from bucket samples are presented for both the Pacific Antarctic 

 Convergence and the Atlantic Antarctic Convergence. Typical BT traces 

 are presented for other locations within the Antarctic operational area. 



1. Antarctic Convergence 



The position of the Antarctic Convergence is identified by a region 

 of sudden increase in surface water temperature when proceeding away 

 from the Antarctic Continent, the rapid change amounting to 2° or 3° F. 

 over a very short distance. Also, surface water south of the convergence 

 is characterized by lower salinity and slightly higher density than sur- 

 face water found north of the convergence. 



a. Pacific Antarctic Convergence — In the South Pacific the 

 Antarctic Convergence was crossed enroute from New Zealand to the Ross 

 Sea. The main convergence or zone of convergence occurred between 62° 

 ^nd 63° S. Surface water temperatures dropped from itl° to 38° F. 

 approaching the convergence and from 38° to 35° F. at the convergence 

 (fig. 3J.), Air teraperaturp:s were several degrees higher and exhibited 

 a similar drop throughout th? section. Lower salinities were not noted 

 during the first drop in surface water temperature. The second drop in 

 temperature was accompanied by a decrease in salinity, but a time lag 

 of about 5 hours was noted before lower salinity values were obtained. 

 The drop in salinity corresponded roughly with the occurrence of colder 

 surface water or the point at which the ra.pid drop in temoerature 

 terminated. Density began to increase with the first noticeable drop 

 in temperatTire, The slight rise in surface water temperature Just 

 before the drop has been noted in other sections tal<en across tte 

 convergence. 



Figure 12 shows a vertical section of temperature across the 

 Pacific Antarctic Convergence, The isotherms are drawn at intervals 

 of 1° F. and are based upon temperatures recorded on the BT traces. 

 The flow of colder Antarctic water under the warmer water to the north 

 of the convergence is readi]jr apparent if the 37° F, isotherm is taken 

 as the boundary between the contrasting water masses. Approaching 

 Antarctica, water temperatures of 32° F, or lower were not apparent 

 on the BT traces until the zone of convergence was reached. The tongue 

 of cold xirater, "winter water," advancing from the south is t.\Tpical of 

 such sections across the convergence. The wide gap in observations 

 immediately south of the convergence occurred when the weather became 

 too rough to permit taking BT casts, 



b, Atlantic Antarctic Convergence— In the South Atlantic the 

 Antarctic Coni'-ergence was crossed just northwest of South Ceorgia Island 



32 



