HYDROLOGY OF THE AREA S 



At the convergence the temperature range of the Antarctic surface water is approxi- 

 mately 0-5 to 3-0° C. in winter, and 3-0 to 5-5° C. in summer. The position of the con- 

 vergence varies somewhat with the time of year, and also from season to season: in a 

 heavy ice year the northward flow of the Antarctic surface water may be increased 

 appreciably above normal. The effect of the land on the two main water masses con- 

 cerned causes a considerable variation in the latitude of the convergence with longitude. 

 Thus it will be seen from Fig. i, in which the average position of the Antarctic con- 

 vergence in the South Atlantic is shown, that it takes a big sweep southward as far as 



10 



20 



30° 



40 



50 



60 



80° 70° 60° 50° 40° 30° 20° 10 



10° 20° 30 



1: 



^ 



Antarctic Zone 



Souvet 



6d 



80° 



70° 



eo° 



50° 



40" 



30° 



20° 



10° 



10 



20° 



30° 



Fig. I. Chart showing the probable average positions of the Antarctic, sub-tropical and tropical con- 

 vergences in the South Atlantic (from information supplied by Mr Deacon). 



58^° S on rounding the Horn, and begins to bend sharply northwards due south of the 

 Falkland Islands. The northward trend becomes even more marked between 50 and 

 43° W longitude, where the convergence runs almost north-east and south-west, passing 

 between the Falkland Islands and South Georgia well to the north of the latter island. 

 Farther east the convergence continues to incline very gradually northwards, reaching 

 47° 40' S in the meridian of Greenwich, but north of Bouvet Island it again begins to 

 trend slightly southward. Recent work of the R.R.S. ' Discovery II ' during her circum- 

 navigation of the Antarctic Continent will probably enable the position of the con- 

 vergence to be determined all the way round the world, but the above description 



