1 80 WATER MASSES AND CURRENTS OF THE OCEANS 



outflowing water is increased from about 16.00°/oo where it enters the 

 Strait of Bosporus to nearly 30.00°/oo where it leaves the Dardanelles. 

 The outflowing and inflowing water masses are separated by a well-defined 

 layer of transition that oscillates up and down according to the contours 

 of the bottom. The currents through the Strait of Bosporus can well 

 be compared to two rivers flowing one above the other in a river bed that 

 has a width of about 4 km and a depth of 40 to 90 m. 



Fig. 47. Surface currents (solid arrows) and currents at intermediate depths 

 (dashed arrows) in the Mediterranean Sea (after Nielsen). 



Appreciable water masses pass through the Strait. According to 

 current measurements and other observations by A. Merz, the most 

 probable values of the outflow and inflow through the Strait of Bosporus 

 are 12,600 mVsec and 6100 mVsec, respectively. (The Mississippi River 

 carries, on an average, 120,000 m^/sec.) The difference between inflow 

 and outflow, 6500 m^/sec, represents the excess of precipitation and run- 

 off over the evaporation. Precipitation and run-off have been estimated 

 at 7600 and 10,400 m Vsec, respectively, and the evaporation should there- 

 fore amount to 11,500 mVsec, or 354 kmVyear. The area of the Black 

 Sea is 420,000 km^, and the above value therefore corresponds to an 

 evaporation of 84 cm per year, in good agreement with observed and 

 computed values for this latitude (p. 68). 



The Caribbean Sea and the Gulf of Mexico. The surface cur- 

 rents in spring are shown in fig. 48. A strong current passes through the 

 Caribbean Sea and continues with increased speed through the Yucatan 

 Channel. There it bends sharply to the right and flows with great 

 velocity out through the Straits of Florida. On the flanks of the main 

 current, numerous eddies are present, of which the one in the wide bay 

 between Nicaragua and Colombia and the one between Cuba and Jamaica 

 are particularly conspicuous. In the Gulf of Mexico, several large eddies 

 exist, all of which appear to be semipermanent features, and their loca- 

 tions seem to be determined by the contours of the coast and the con- 

 figuration of the bottom. 



