VERTICAL CIRCULATION IN THE OCEAN 



151 



to the north, but the temperature section gives a different picture. North of the con- 

 vergence the isotherms bend towards the south and a tongue of water with temperature 

 higher than 2° extends past latitude 64° S between the depths of 400 and 1 500 m. This 

 distribution of temperatures indicates that between these depths the current has a com- 

 ponent which carries back to the south part of the water which has been transported to 

 the north by the pure drift current. To the north of the convergence and below the 

 Antarctic intermediate current, processes of mixing seem to take place, and through this 

 mixing the salinity of the sinking water increases and the temperature decreases. The 

 returning current, which is composed of Antarctic water and deep water, therefore 

 has a greater density than the water of the pure drift current, but before it again 

 reaches the surface it is diluted by melting water from the ice and by precipitation, 

 and thus a further development of the solenoid field is prevented. 



Fig. 2. Chart showing the location of the vertical sections. 



It seems, however, that only part of the water which has been transported to the north 

 returns again to the south. In order to complete the compensation, the deep water 

 below 1500 m. must also have a component towards the south, and finally the bottom 

 water appears to have a component to the north. Below the vertical circulation of the 

 upper layers, we, therefore, must have a similar circulation, which, when looking in the 

 direction of the current, rotates clockwise, while the circulation of the upper layers 

 rotates counter-clockwise. The possible circulations are indicated in the sections by 

 means of arrows. In this and the following sections the arrows were first plotted by 

 means of the temperature distribution and afterwards entered on the other diagrams. 



The author is aware that great caution must be exercised when drawing conclusions 

 as to presence of currents from tongue-like distributions of oceanographic elements. 

 Later, other features will be discussed which confirm our conclusions, but now we shall 

 proceed with a discussion of the other vertical sections. 



Figs. 5-10 show the sections II and III through the Drake Passage, one made by the 



