688 The Stratospheric Circulation 



and then breaks up into vortices. The third much weaker branch meanders along the 

 East Atlantic Trough past Madeira to the Canaries and the Cap Verde Islands and a 

 side branch of it seems to enter the Guinea Bight. The course of the first two branches 

 under the influence of the Coriolis force used apparently the bottom morphology as 

 guiding limits for their spread. The westernmost and most important branch keeps also 

 in the Southern Hemisphere at first close to the continental slope until about 25° S. 

 and then bends towards east-south-east and fills from here as a broad water transport 

 the total oceanic space between 25° S. and 40° S. Finally, it passes south of Africa into 

 the Indian Ocean. The velocities in the Northern Hemisphere branches of the current 

 are seldom more than 2 cm/sec. Where the current concentrates along the South 

 American continental slope it reaches about 3-4 cm/ sec until 15° S. and at Cap San 

 Roque it reaches maximum speeds of 8-12 cm/sec before falling off to 0-5-1 -5 cm/sec 

 further south. 



The spread of middle North Atlantic Deep Water as deduced from the oxygen 

 content of its core layer is shown in the left-hand chart of Fig. 327 ; the arrows in this 

 figure indicate the principal branches of spread determined from the dynamic topo- 

 graphy of the pressure surfaces. The agreement between the results of the two methods 

 is remarkable. Sverdrup (1930) has given a diagram showing the deep currents in the 

 southern part of the South Atlantic based on the "Carnegie" observations that fits 

 well in the topography of the 2000-decibar surface. 



WiJST (1957) has calculated the corresponding velocities at right angles to the 

 "Meteor profiles" for the current course of the Atlantic Deep Water in the area 

 between 10° N. and 30° S. The distribution of these velocity components is presented 

 in Fig. 328 and shows obviously good agreement with the distribution in the right- 

 hand diagram of Fig. 326. In the core the velocity (reduced to the "true" direction) 

 is now 9-2 cm sec~^ with individual values varying between 2-1 and 17-4cmsec"^. 

 It should especially be noticed that also here the flow is concentrated towards the west 

 just off" the American continent while the eastern parts of the oceans are completely 

 inactive. 



In the Indian Ocean a deep current stands out between 2000 and 3000 m marked 

 by a highly saline deep layer and a pronounced temperature inversion. Its strong 

 development is due primarily to the large density differences between the equatorial 

 and polar water masses which are continuously renewed by the supply of salt from the 

 Red Sea and the Persian Gulf (Pt. I, pp. 183 and 529). A deeply penetrating detailed 

 analysis of some oceanographic series observations in the Indian and Pacific Oceans 

 has been made by Helge Thomsen (1933, 1935). From the [rS'J-diagrams it appears 

 rather doubtful whether there is actually a deep current in the Indian Ocean between 

 2000 and 3000 m similar to that in the Atlantic. On the other hand, the Intermediate 

 Current and the Bottom Current are well developed as well as the effects from the 

 Red Sea are easily followed far to the south. 



8. A Survey of the Water Transports in the Individual Layers of the Atlantic Ocean 



The total amounts of the water transport in meridional direction in the South 

 Atlantic total space (between 5°S. and 35° S.) which Wiist has derived from mean 

 velocity values calculated from the individual profiles of the "Meteor" expedition are 

 of great interest. The most important results arc summarized in Table 157. The figures 



