210 



WATER MASSES AND CURRENTS OF THE OCEANS 



From the foregoing it is evident that one cannot consider the Antarc- 

 tic Circumpolar Water Mass as a body of water that circulates around 

 and around the Antarctic Continent without renewal. On the contrary, 

 one has to bear in mind that water from the antarctic region is carried 

 toward the north and out of the region both near the surface and near 

 the bottom, and that deep water from lower latitudes is drawn into the 



■5o«'^°^.o- 



CO^ .SUB -ANTARCTIC 



REGION 



-*^^S^' 



ANTARCTIC 



Fig. 59. Schematic representation of the currents and water masses of the 

 Antarctic regions and of the distribution of temperature. 



system in order to replace the lost portions. Through external processes, 

 cooling and heating, evaporation and precipitation, freezing and melting 

 of ice, and through processes of mixing, the temperature and salinity in a 

 given locality remain nearly unchanged over a long period, except for 

 such changes as are associated with displacements of the currents. Thus, 

 the stationary distribution of conditions that characterizes the entire 

 Antarctic Ocean represents a delicate balance between a number of 

 factors which tend to alter the conditions. On the other hand, an 

 individual water particle, which describes a most complicated path, is 

 subjected to great changes. It may lose its identity by mixing with 

 adjacent water masses, or it may have its temperature and salinity 

 radically altered if brought to the surface. 



When examining the dynamics of the Circumpolar Current, frictional 

 forces have to be taken into consideration. The stress that the wind 

 exerts at the sea surface cannot be balanced by a piling-up of water in 



