The Tropospheric Circulation 



617 



Fig. 289. Mean temperature (°F) in the upper 200 m layer on 17 June 1950. Current 

 direction from geomagnetic electrokinetograph (GEK) (according to Arx, 1950). 



(2) Why does the Gulf Stream keep such a concentrated narrow form over a long 

 distance sometimes taking on a meandering character? Why does it break up into 

 several smaller branches separated by motionless bands or weak counter currents? 



(3) Why is the total energy of the current concentrated in a relatively thin top layer 

 and why does the current not penetrate down to the deeper layers when it flows out 

 over regions with larger depth? 



Research on these questions is in progress but more fundamental results have been 

 obtained only for some individual questions. It appears that these strong oceanic 

 boundary currents are analogous in many respects to the "jet streams" of the strong 

 westerlies in the upper atmosphere and are especially characteristic for the dynamics 

 of free jets. 



(c) To the Dynamics of the Gulf Stream 



RossBY (1936, 1937, 1938) in a series of papers has advanced some new ideas on the 

 theory of ocean currents which are of some interest. These arguments have been 

 applied primarily to the Gulf Stream System between the Florida Strait and the area 

 south of Newfoundland. But their use is not limited to these currents and in many 

 respects they can also be appHed to all boundary currents flowing parallel to a coast 



