Hydrography of the Stream 



57 



temperature are directly correlated. The main thermocline (10° C. iso- 

 therm) drops from 200 to 900 m. across the Stream in less than 70 nautical 

 miles. The temperature-versus-depth curve of the water below the 16° 

 isotherm is nearly the same on the two sides of the Stream, except for a 

 vertical displacement of about 700 m. The chief dissimilarity between the 

 water above the main thermocline on the one side of the Stream and that 



94 56 58 60 

 STA. 4853 55 67 59 61 62 63 64 65 66 4867 



Fig. 34. The geostrophic current velocity (cm. /sec), according to Worthing- 

 ton's (19546) closely spaced section (his fig. 10). 



on the other consists in diflferences of temperature of the upper 200 m. and 

 the presence of a large body of nearly isothermal water (ca. 18° C.) between 

 200 and 600 m. on the Sargasso Sea (right-hand) side. 



From a computation of transport, obtained from fifteen crossings, Iselin 

 (1940) has shown that the total transport of the Gulf Stream above 2000 m. 

 in this area is between 76 x 10« and 93 x 10« cm.^/sec. Fig. 34 shows the 

 geostrophic velocity across the Stream in centimeters per second. The 



