The Stratospheric Circulation 



683 



bottom currents. The Antarctic bottom current in the Southern Hemisphere shows 

 measurable velocities (>3 cm sec~^) only close to the western side of the West Trough, 

 that is, at the foot of the continental slope and about 1000 m above the level of the 

 proper deep-sea bottom. With few exceptions only very weak velocity components 

 were found in the east. These results derived from dynamical computations agree well 

 with the above described ones. With these new velocity values the water masses of the 

 bottom would need about 5-5 years in order to travel from the southern rim of the 

 Argentine Basin (48° S.) to the northern rim of the Brazilian Basin (5° S.). 



7. The Deep Currents in the Middle Part of the Oceanic Stratosphere of Individual 

 Oceans 



In a fully symmetrical ocean there would be in each hemisphere a subpolar inter- 

 mediate current in the uppermost part of the oceanic stratosphere and a polar bottom 

 current in the lowermost part of it. These water transports directed towards the 

 equator for reasons of a compensation require an additional poleward water trans- 

 port in the middle part of the stratosphere. These compensation movements are 

 called the "deep currents" of the oceans. 



In this way the scheme of the meridional components of the stratospheric circulation 

 (Fig. 323) thus consists of two closed circulations in each hemisphere; one circulation 

 in the upper part of the oceanic stratosphere containing the intermediate current and 

 the upper half of the deep current and moving in a clockwise sense when looking east 

 in the Northern Hemisphere, and a second circulation in the lower part of the oceanic 

 stratosphere that includes the polar bottom current and the lower half of the deep 

 current and moves in an anticlockwise sense. It should be borne in mind in looking at 

 Fig. 323 that only the meridional flow components of the two circulations are shown 

 which are always weaker than the zonal ones. 



The rather varying character of the polar components in the actual oceans gives 



60° 



40° 



E0° 



0° 



20° 



40° 



60° 



Fig. 323. Schematic representation of the meridional components of the oceanic circulation 



in a symmetrical ocean. -« < , circulation of the troposphere; •^— , subpolar intermediate 



currents; < , polar bottom currents of the stratosphere; < , mean deep currents of 



the stratosphere; , limit between oceanic tropo- and stratosphere; P, polar front 



(polar convergence); C, subtropical convergence; E, equatorial counter current. 



