3. BURTON ISLAND crossed the Convergence during March i960 from 

 about 61 ° to 65 °S along the 91° through 95 «W meridians. During this 

 crossing, both BT and Nansen cast observations vere made. 



Figure Ik presents the results of BT observations, shoving detailed 

 surface structure. 



It is noted that the Convergence Zone in this section compared to 

 previous sections appears to be considerably broader. South of the 

 Convergence, surface temperatures decrease regularly, with water of 

 temperatures less than 30°F appearing at the surface at the southern 

 end of this section. 



C. Oceanographic Station Sections 



During February, BTF.TON ISLAND occupied stations southward from 

 Valparaiso, Chile, to the vicinity of Thurston Peninsula. In March, 

 the ship returned along approximately the same track, taking a 

 continuous series of stations from Peter I Island to Concepcion, Chile. 

 Oceanographic conditions observed to the 2000-meter depth during this 

 leg are shown in Figures 15 and 16. The cross section for temperature 

 indicates the Convergence near stations 39 (6o e lkL'S) and to* (6l°ll'S). 

 Observational depths in this vicinity were limited to about 500 meters, 

 owing to adverse sea conditions. 



These sections are good examples of physical conditions 

 characteristic of the Antarctic and Subantarctic regions. The main 

 features of the water masses are discussed in previous sections; however, 

 these figures show physical features much farther north than the others. 



A series of oceanographic stations was made across the Convergence 

 in Drake Passage by GLACIER during March i960. Figure k shows the 

 position of the Convergence in this area and Figure 11 presents vertical 

 distribution of the physical properties of the water. A discussion of 

 this crossing is in Section IV, Drake Passage Oceanography. 



D. Continuous Surface Temperature Record 



Figure 17 is a continuous trace of surface water and shade-air 

 temperatures, measured by resistance bulb thermometers, across the 

 Antarctic Convergence in Drake Passage. Temperatures increased from 

 3-h° at 55°22.Vs to 7.2°C at 55°lVs. Associated air temperatures 

 gradually increased from 5.8° to 7.3"C. 



29 



