shows the dynamic topogi^aphy found at the Bonavista triangle during 

 the postseason cruise about a month later. During this interval there 

 was an eastward shift of the current pattern along the northwest 

 section of the triangle and this topography was interpreted to mean 

 that any bergs entering the area from the north and crossing the 49th 

 paraUel west of about 51°30' W., would, follow the western branch, 

 that those crossing this parallel between 51°30' W., and 49°50' W., 

 would strand on the Grand Banks and that those crossing eastward of 

 about 49°40' W., would reciu-ve eastward and northeastward without 

 reaching latitude 47° N. 



In the Grand Banks region Labrador Current water and Atlantic 

 Current water have characteristic temperature-salinity relationships 

 which identify them as water masses. Here also these parent water 

 masses usually mix in a sufficiently constant proportion so that the 

 mixed water can be regarded as a vhtual water mass. In 1955 only 

 the first survey was located in the area which has been the soiu-ce of 

 the T-S data considered in the past. The relationships found during 

 this survey are shown as solid lines in figure 17 and are compared with 

 averages for the 8-year period 1934-41, shown in broken lines. The 

 1955 T-S curve for Labrador Current water is like that for the 8-year 

 mean but is fresher than the mean below about 400 meters. The 

 mixed water in 1955 was fresher than the mean and slightly warmer 

 throughout. In 1955 the Atlantic Current water was slightly saltier 

 than the mean above 600 meters and fresher below that level. It 

 was also slightly warmer than the mean above about 800 meters. 

 In 1955, level for level, all the water masses were lighter than the 

 mean at all levels. Geographically, the northern sections show 

 normal Labrador Current water. In the southern sections there was 

 some mixing of Labrador Current water with mixed water in the 

 area usually occupied by Labrador Current water. Also the southern 

 sections showed some mixing of mixed water with Atlantic Current 

 water. The Flemish Cap area was occupied by normal mixed water. 



For the first and only 1955 survey which extended far enough south 

 to include a portion of the cold wall its position was determined as in 

 other years using as a criterion the horizontal projection of the line 

 along which a temperature of 6° C corresponds to a salinity of 

 34.95°/oo. The area included between this boundary and rhumb 

 lines of the 45th parallel, the 49th meridian from 45° N., to 43° N., 

 and a line from 43° N., 49° W., through 42° N., 47° W., extended to 

 the boundary, was 8.5 x 10* square kilometers. This area, adjusted 

 for the volume transport of the Labrador Current entering the area 

 past the 45th parallel, reduced to 5.16. This adjusted area, A, did 

 not compare well with the 2.30 computed from the prediction formula, 

 A=6. 97(11— 5.07)-fl. 67 in which A is the adjusted area and H, 

 expressed in feet, is the sea level at Charleston, minus the departure 

 from average sea level at Bermuda 11}^ months earlier. As only one 



69 



