and of these 12 are regarded as useable in comparing the TD measure- 

 ments with reversing thermometers. 



As in previous years routine saHnity determinations were made 

 with a Wenner saHnity bridge. Standardizations were made with 

 water from an oil-sealed carboy of sea water and at least twice during 

 each run a sample of Copenhagen standard water of the batch Pi 7 

 was measured as an unknown. At the end of each survey these 

 measurements of Copenhagen water were used to correct all the 

 salinities measured during the survey. For each of the surveys, 

 including the postseason cruise, these indicated corrections were less 

 than 0.005°/oo and so no corrections have been made. 



Figures 14 through 17 show, in chronological order, the dynamic 

 topography of the sea surface found during the four surveys made 

 during the season. Figure 14 shows the Labrador Current along the 

 eastern edge of the Grand Banks to have had a subnormal surface 

 speed but increasing to swifter than usual at the Tail of the Banks, 

 Bergs entering this pattern from the north might reach the Tail 

 of the Banks and drift thence westward to longitudes of between 

 50°30' W., and 51°50' W., thence southward to about 42° N., and 

 thence easterly. There was little liklihood of bergs reaching farther 

 south than about 41°45'' N. At the southern edge of the surveyed 

 area the Atlantic Current was flowing with considerable strength 

 and the height of 971.776 dynamic meters at station 5012 is probably 

 the highest that has been found by the ice patrol in the area covered 

 by this survey. An associated feature of figure 14 is that the pool of 

 cold mixed water, which has frequently been found extending south- 

 easterward from the Tail of the Banks, was of smaller extent than 

 usual. Bergs entering the area from the north and crossing the 46th 

 parallel between about 47° W., and 47°30' W., could have been taken 

 in a southeasterly direction to positions of potential hazard to the 

 North Atlantic Track Agreement tracks betv/een about 45° N., and 

 46° N. 



The areas covered by the first and second surveys overlap between 

 about 44°30' N., and 46° N., but this is insufficient to permit following 

 particular meanders with certainty. In the Labrador Current shown 

 in figure 15 the southward path to the Tail of the Banks apparently 

 remained unobstructed for those bergs which might have passed the 

 47th parallel between longitudes of about 47°15' W., and 48°00' W. 

 As in the first survey, figure 15 shows the possibility of bergs entering 

 the area from the north proceeding in a general southeasterly dii'ection 

 to menace the Track Agreement tracks between about 45° N., and 

 46° N. In fact a weak clockwise eddy centered over the northern 

 part of Flemish Cap appeared to be the only obstruction to the 



55 



