126 



of any quantitative information regarding the degree of protection 

 against vertical mixing afforded by steep vertical density gradients 

 near the surface. 



It is of interest, then, to examine the magnitude of the effect of uni- 

 form mixing of the upper layers under such conditions of distribution, 

 if such uniform mixing were possible. For illustration, the actual 

 section across the Gulf Stream located at about the fiftieth meridian 



^400r 



Figure 50.— Temperature profile across Gulf Stream near fiftieth meridian, June 3-4, 1938. 



south of the Grand Banks, and occupied during the third current sur- 

 vey, June 3-4, 1938, has been examined. Figure 50 shows the tem- 

 perature distribution along this section. It was assumed that the upper 

 100 meters was uniformly mixed at each of the stations and the result- 

 ing mean values of temperatures and salinities were used to determine 

 anomalies of dynamic height for the upper 100 meters. At each sta- 

 tion the resultmg figure was compared with the anomaly of dynamic 

 height computed from the measured values of temperature and salin- 

 ity. The changes in dynamic height of the surface which would occur 



