WATER MASSES AND CURRENTS OF THE OCEANS 



167 



the momentum transport remains constant, whereas the volume (mass) 

 transport increases downstream, the increase being due to inflow from the 

 sides. Expanding the theory to a stratified medium, Rossby finds that a 

 ''compensation current" in the direction of flow must develop on the 

 right-hand side of the wake stream, whereas to the left a counter-current 

 in the opposite direction must appear, and this picture agrees in general 

 with the pattern of the Gulf Stream and its surroundings. Another 

 important aspect of the theory is that, owing to the lateral stresses, a 

 transverse circulation should develop, water being absorbed from the 

 oceanic areas to the right of the current and discharged into the counter- 

 current to the left. Such a mechanism would account for the presence of 

 eddies of Gulf Stream water in the slope current, but Defant and Ekman 

 have warned against immediate acceptance of the theory, because several 

 of the necessary assumptions appear not to be fulfilled. Regardless of 

 whether the theory is confirmed or disproved, it has been greatly stimu- 

 lating, particularly because of its emphasis on the importance of lateral 

 mixing. 



Table 18 



AVERAGE SEA LEVEL ALONG THE NORTH AMERICAN EAST COAST 

 REFERRED TO SEA LEVEL AT THE COAST OF FLORIDA-GEORGIA 



A satisfactory theory of the Gulf Stream must account not only for the 

 increase in volume transport in the direction of flow and the fact that this 

 increase takes place without evidence of strong inflow from the southeast, 

 but also for another important feature that has been given considerable 

 attention without having been explained satisfactorily. Precise leveling 



