30*- 



33" 



36* 



39 



42' 



i i I 1 1 1 L. 



12' E 



If 



Ik' 



28 



32' 



Figure 5. — Surface temperatures off South Africa, March 1969 (from Bang, 1970b). 



penetration is in late summer, the minimum in 

 spring, although such penetration could occur at any 

 time of the year. 



The South East Atlantic Surface water frequently 

 extends across the Agulhas Bank under the influ- 

 ence of the westerlies in winter. Surface currents 

 then are frequently southerly along the west coast 

 and easterly over the Agulhas Bank. During sum- 

 mer, the South East Atlantic Surface water can fre- 

 quently be observed as an intrusion between the 

 upwelled component of the Benguela Current Sys- 

 tem and an Agulhas extension. Figure 10a shows a 

 large intrusion of South East Atlantic Surface water 

 extending over the Agulhas Bank, while Figure 5 

 shows a thin lens of such water along the edge of the 

 Bank, being outflanked by a northwesterly arm of 

 the Agulhas Current. With the seasonal interplay of 

 northwesterly and southeasterly winds the penetra- 

 tion of South East Atlantic Surface water will vary to 

 a greater or lesser extent. Duncan and Nell (1969) 



report that between Cape Agulhas and the Cape of 

 Good Hope the summer flow is strongly east to 

 west, and in winter the flow is reversed and weaker. 



DESCRIPTION OF OCEAN CONDITIONS 

 DURING THE SURVEY PERIOD 



Summer, January 1961 



(Shannon, 1966; Fig. 6a,b) 



The Agulhas Current (>22°C and 35.4-35.5%o), 

 extends over a considerable portion of the Agulhas 

 Bank, reaching close inshore in the Cape Agulhas 

 region. In addition, the Current extends around the 

 Agulhas Bank and penetrates to the northwest up to 

 about 32°S, the core of the warm-water extension 

 being 150 nautical miles offshore. An isolated eddy 

 of northward travelling Agulhas water is notable at 

 lat. 36°S. South Atlantic Surface water is confined to 

 the west of long. 15°E, that is greater than 200 nauti- 



182 



