WATER MASSES AND CURRENTS OF THE OCEANS 



181 



The presentation of the currents in fig. 48 is based on ships' observa- 

 tions. When attempting a calculation of currents by means of numerous 

 Atlantis data from the Caribbean Sea, Parr found that the flow is not 

 directed parallel to the contours of the isobaric surfaces, but that between 

 the Lesser Antilles and the Yucatan Channel the current flows uphill. 

 Parr suggested that this feature may be due to a piling up of water in 





MILES /24^ 

 <— 0-10 



< 10-20 



< 20-30 



^ >30 



^ 



^ 



>> 



Fig. 48. Surface currents in spring in the Caribbean Sea and the Gulf of Mexico 

 (after Dietrich). 



front of the narrow Yucatan Channel that was caused by the stress 

 exerted on the surface by the prevailing easterly winds (p. 122). This 

 idea was further examined by Sverdrup, who concluded that the piling 

 up of the surface water can be fully explained as the effect of winds blow- 

 ing with an average velocity of about 10 m/sec, which agrees well with the 

 observed values in spring. A further consequence of this piling up is that 

 in the Gulf of Mexico a sea level is maintained higher than that along the 

 adjacent coast of the United States facing the Atlantic Ocean. At Cedar 

 Keys, off the southwest tip of Florida, the average sea level is 19 cm 

 higher than the average sea level at St. Augustine, Florida, on the east 

 coast. This indicates that the prevailing winds over the Caribbean Sea 

 produce a hydrostatic head which, according to Montgomery, may 

 account for the major part of the energy of the Florida Current (p. 164). 



Currents of the Equatorial Part of the Atlantic Ocean 



In the equatorial region the water masses below a depth of 50 to 150 m 

 are separated from the surface waters by a laj^er within which the density 

 increases so rapidly with depth that it has the character of a discontinuity 



