southern part of the surveyed area the westward extension of Labrador 

 Current flow has moved eastward to about the western hniits of the 

 survey. The margin of the Athintic Current shows some strengthen- 

 ing and the tongue of cold mixed water which previously extended 

 southward at about 49° W., is seen to be somewhat east of that 

 longitude and very nearly obliterated in the third survey. The 

 meander pattern along the margin of the Atlantic Current in the 

 eastern half of the surveyed area has moved northeastward and 

 smoothed out since the first survey. 



The dynamic topography found during the fourth survey is shown in 

 figure 22. There appears to be little change between conditions 

 observed during the fourth survey and those found during the second 

 survey. The Labrador Cm'rent follows essentially the same path 

 with approximately the same magnitudes, except that in the vicinity 

 of 48° N., 48° W. there appears to be less banding than was found 

 during the second survey. The dynamic topography showed little 

 relief in the northeastern part of the area during both the second and 

 fourth siu-veys. Icebergs entering from the northwest and crossing 

 the 49th parallel east of 52°45' W. would follow the eastern branch 

 of the Labrador Current and those crossing east of about 49°35' \Y. 

 would probably be diverted eastward and not get south of 47° N. 



Figure 23 represents the dynamic topography of the Bonavista 

 triangle found during the postseason survey. The slight irregularities 

 in the Labrador Current in the northwestern section, indicated as 

 eddies in figures 20 and 22, have disappeared, leaving the remarkably 

 simple pattern shown in figure 23. During each of the thi-ee occu- 

 pations of the Bonavista triangle in 1962 the division between eastern 

 and western branches of the Labrador Current occurred closer to the 

 Newfoundland coast than usual. 



In the Grand Banks region the temperature-salinity relationships 

 of both the Labrador Current and the Atlantic Current identify them 

 as water masses. Here the mixing of these two masses is usually in a 

 sufhciently constant proportion so that the mixed water may be con- 

 sidered a virtual water mass. The solid lines in figure 24 represent 

 the 1962 T-S averages based on observations made during the first 

 and third surveys; the dashed lines illustrate the normals for the 

 15-year period 1948-62. In 1962 the temperature minimum in the 

 Labrador Current occiu'red at a depth of approximately 50 meters 

 whereas the normal depth of this minimum is more nearly 75 meters. 

 Also, the Labrador Current water was warmer than normal through 

 600 meters. The salinities were greater than normal through 100 

 meters, and the corresponding densities were slightly heavier than 

 normal; at 150 meters and below, the salinities and densities were 

 less than normal. The Atlantic Current was fresher and colder than 

 nonnal, but the resultant densities showed hardly any change from 

 the normal. The mixed water mass was warmer than normal; down 



695-672 0-64-4 41 



