T-S relationships as being probably too far removed from the source 

 of the other data for direct comparison. The results of the first, 

 second, and fourth surveys were examined separately and it was 

 found that while there were differences from survey to survey these 

 differences were small. However, because of geographical differences 

 only the Atlantic Current water stations of the second survey were 

 included in the average values for 1953. These T-S relationships 

 for the three water masses are shown in figure 36 as solid lines in 

 comparison with the averages for the 8-year period 1934-41 which 

 are shown as broken lines. 



The Labrador Current water was somewhat fresher from 50 to 

 100 meters, somewhat colder from 100 to 400 meters, and both colder 

 and fresher below 400 meters than the 8-year mean. The mixed 

 water was fresher than the 8-year mean at all levels. The Atlantic 

 Current water appeared to be warmer and saltier above about 800 

 meters, and warmer and fresher below that level, than the 8-year 

 mean. Again in 1953 the salinity minimum at a temperature of 

 about 6° was not apparent in the mean for the year although some 

 individual station curves exhibited it. If this minimum is the result 

 of mixing and is, as has been assumed, a characteristic of the outer 

 margins of the Atlantic Current water mass, the minimum may have 

 disappeared from the yearly average because of a larger number of 

 stations taken farther into the Atlantic Current water mass. 



The number of atypical stations, that is, stations which do not 

 definitely fall into one of the water mass categories, was larger than 

 usual. In the first survey there were 6 stations between Atlantic 

 Current water and mixed water characteristics and 9 such stations 

 in the fourth survey. In addition there were evidences that bound- 

 aries between water masses were not vertical, with one water mass 

 over a different water mass at each of several stations. The Labrador 

 Current water (for which more stations were available than for other 

 water masses) was saltier during the second survey than either the 

 first or fourth surveys and except for the 50-meter level it was fresher 

 during the first survey than during the fourth. The differences 

 were small enough to be of doubtful significance. 



As a check on whether the mixed water was or was not a virtual 

 water mass, the probable departures of temperature and salinity at 

 a given level at an individual station, from the temperature and salin- 

 ity at that leval on the T-S curves for 1953 shown in figure 36 were 

 computed for each level for each water mass. These probable de- 

 partures were then used as the axes of elipses of uncertainty con- 

 structed with their centers at the appropriate points on the T-S 

 curves. Level for level the elipses for Labrador Current water and 

 mixed water did not overlap except at 600 meters and below; and for 

 mLxed water and Atlantic Current water they did not overlap except 

 at the 1,500 meter level. 



78 



