Some interest has been expressed as to whether there has been any 

 progressive change in the sahnity of the North Atlantic eddy over 

 the years. Small consistent differential changes would have a marked 

 effect on circulation. For the postwar years 1948-5;] the T-S points 

 representing the year's mean have been plotted for each year and each 

 level for each of the three water masses found in the Grand Banks 

 region. Such a period of 6 years is too short to reveal any gradual 

 shift in a particular T-S point as the annual excursions of the point 

 are greater than any anticipated permanent shift of the point. 



In each water mass the excursions were greatest in the upper levels 

 and decreased with increasing depth. In the Labrador Current water 

 the major axis of the excursion pattern was parallel to the character- 

 istic T-S curve of the water mass down to about 200 meters, indicating 

 changes in density for a specific level in this depth range. Below 

 about 200 meters the fluctuations were more nearly isopycnal. No 

 such regularity was apparent in the plots for the mixed water, In 

 the Atlantic Current water the major axis of the excursion pattern 

 was roughly parallel to the characteristic T-S curve down to about 

 800 meters but below that depth there was no pronoum-ed major 

 axis in the pattern. Caution must be used in interpreting these 

 measurements made in Atlantic Current water because, unlike the 

 measurements in the other two water masses, these sample only the 

 outer part of the North Atlantic eddy and so must contain a varying 

 proportion of marginal stations from year to year. Thus while the 

 geographical distribution of the sampling is roughly the same from 

 year to year, the fluctuations recorded may represent fluctuations in 

 geographical position of the margins of the North Atlantic eddy rather 

 than fluctuations in its T-S characteristics. 



In comparison with the 8-year mean for the period 1934-41, the 

 postwar observations in the Labrador Current water were fresher 

 and slightly colder in the upper 200 meters and fresher below 400 

 meters. The mixed water was fresher at ah levels and the Atlantic 

 Current water was warmer and fresher below about 800 meters. 



In earlier Bulletins of this series attempts have been made to de- 

 scribe numerically the fluctuations in the position of the cold wall 

 and to relate these fluctuations to other phenomena. As the cold 

 wall is not vertical the outer margin of Atlantic Current water has been 

 used. This has been defined as the horizontal projection of the line 

 along which a temperature of 6° corresponds to a salinity of 34.95°/oo- 

 This border is serpentine in shape and its position has been character- 

 ized by measuring the area northwestward of it between the border 

 and fixed rumb lines (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.). 

 Thus, as the border moves toward the Grand Banks the area decreases. 

 It was assumed that the position taken up by the border was deter- 

 mined partly by forces associated with the Labrador Current and 



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