Fig. 11. Surface current speeds (knots) computed from dynamic topography relative to 400-meter level 



V. WATER MASS CHARACTERISTICS 



Temperature -salinity correlations are plotted in figures 12a and 

 12b together with a mean curve for the Yucatan Channel (redrawn from 

 Iselin, 1936) which serves as a basis for comparison. The plots in 

 figure 12a represent those stations having the lowest dynamic heights 

 relative to IjOO meters (see fig, 5), and as such are each a part of an 

 enclosed circulation* The plots include stations both in the first 

 and last phase of the PURSUIT survey. In general, the T-S corre- 

 lations below 200 meters in figure 12a fall farther to the right of 

 the Yucatan Channel curve than do the correlations in figure 12b, 

 which represent stations taken in the southwestern section of the 

 survey area (latter phase of survey). The stations in the northwest 

 section have been excluded from these compositesj however, selected 

 portions of their T-S diagrams are shown in figure 13. Of these, 

 the curve for station 17 best fits the correlations in figure 12b. 

 The water in the central section seems fairly well mixed with the 

 water from the southwest and east, while in the northwestern area 

 progressive mixing in the maximum salinity layer (l£0 to 2!?0 meters) 

 is observed. 



The transport calculations across stations in the northwest 

 section (taken in the first phase of the USS PURSUIT cruise) in- 

 dicate an eddy system involving a considerable quantity of water, 

 which is not borne out by the T-S diagrams. In spite of the time 

 lag between phases of the cruise, it is apparent that a fair pro- 

 portion of this water must therefore be diverted southward, as the 

 transport computations using station data from the second phase 

 of the cruise show. 



10 



