DYNAMICS OF THE SOUTHERN OCEAN 141 



a circumnavigation in a cyclonic direction could only end at a higher level than that 

 from which it was started. A similar argument suggests the possibility that the south- 

 ward movement of the deep current in the Southern Ocean may be stronger than the 

 small isobaric gradient from east to west seems to allow. 



In the Atlantic Antarctic basin the converging and diverging currents are modified by 

 the existence of a large cyclonic whirl, but in the remainder of the Southern Ocean most 

 of the water which flows southwards in the deep current seems to return towards the 

 north in the surface and bottom currents. This type of movement, from one layer to 

 another, is also contrary to the assumption of stationary conditions since it must take 

 place across the isosteric surfaces. 



The variations that occur in the inclinations of the paths of the sinking and climbing 

 northward and southward movements — certain to be accompanied by changes of 

 velocity — make the study of the meridional circulation still more interesting. It seems 

 highly probable that the steep gradients found in the neighbourhood of the Antarctic 

 convergence (Deacon, 1934) are a direct consequence of the convergence and divergence 

 of the currents. 



When the existence of such a complex circulation is taken into account, and the rather 

 uncertain factors of wind and friction are remembered, it seems unwise to draw con- 

 clusions as to the presence, absence, or strength of a water movement from the topo- 

 graphical charts alone, and the use of other methods, particularly to estimate the meri- 

 dional water movements, becomes a matter of great importance. 



REFERENCES 



Clowes, A. J., 1933. Influence of the Pacific on the Circulation in the South-West Atlantic Ocean. Nature, 



cxxxi, pp. 189-91. London. 

 Deacon, G. E. R., 1933. A General Account of the Hydrology of the South Atlantic Ocean. Discovery 



Reports, vin, pp. 171-238, Pis. viii-x. Cambridge. 

 1934. Nochmah: Wie entsteht die Antarktische Konvergens? Ann. Hydrog. Mar. Meteorol., xn, 



pp. 475-8, PI. 61. Hamburg. 

 1937. The Hydrology of the Southern Ocean. Discovery Reports, xv, pp. 1-124, Pis. i-xliv. Cam- 

 bridge. 

 Defant, A., 1935. Zur Dynamik des antarktischen Bodenstrotnes im Atlantischen Ozean. Zeitschrift fur 



Geophysik, Jahrg. 11, Heft 1/2, pp. 50-5. Brunswick. 

 Ekman, V. W., 1928. A Survey of some Theoretical Investigations on Ocean Currents. Journ. du Conseil, III, 



no. 3, pp. 295-327. Copenhagen. 

 Helland-Hansen, B. and Nansen, F., 1926. The Eastern North Atlantic. Geofysiske Publikasjoner, iv, 



no. 2. Oslo. 

 Hesselberg, Th. and Sverdrup, H. U., 1915. Beitrag zur Berechnung der Druck- und Massenverteilung im 



Meere. Bergens Museums Aarbok, 1914-15, nr. 14. Bergen. 

 Krummel, O., 191 1. Handbuch der Ozeanographie, 1, 11. Stuttgart. 

 Meyer, H. H. F., 1923. Die Oberfiachenstrbmungen des Atlantischen Ozeans im Februar. Veroffentl. Inst. 



Meereskunde, xi, pp. 1-35. Berlin. 

 Michaelis, G., 1923. Die Wasserbewegungen an der Oberflache des Indischen Ozeans im Januar und Juli. 



Veroffentl. Inst. Meereskunde, vm, pp. 1-32. Berlin. 



u xv 3 



