97 



o-,= -0.0934 + 0.81487aS'-0.0004825*S2 + 0.00000677>S3 



From this relationship corresponding vahies of ag have been computed 

 for each 0.1 °/oo sahnity over the range from 32.5 to 36.5°/oo and are 

 given in table 3. 



Table 3 



Using the value of ag derived from the first curve, the second curve 

 gives the appropriate value of salinity corresponding to the given 

 temperature and the chosen value of o-,. From a number of points 

 so derived a curve of constant at can be drawn on a temperature- 

 salinity plot. 



The first survey of the season was subjected to a shallow-water 

 isentropic analysis to see if the circulation pattern indicated by such 

 an analysis would differ materially from that given by the dynamic 

 topography and to get information on the order of magnitude of the 

 range in depth of such an isentropic surface over the area involved. 

 The surface of o-j=27.2 was selected for analysis as tliis was the 

 shallowest surface covering the entire area of the survey. Tempera- 

 tures and salinities at this surface and the depths of the surface were 

 determined at each station of the survey at which the density was 

 sufficiently great. Both the temperature and salinity distributions 

 on the surface of o-«=27.2 gave circulation patterns in general agree- 

 ment with that given by the dynamic topography. The depth of the 

 surface considered varied from 0, in the region of lowest dynamic 

 height in the northern part of the survey, to 660 meters, in the region 

 of highest dynamic height in the southern part of the survey in the 

 northern edge of the Gulf Stream. At the shallower stations on the 

 Grand Banks side of the Labrador Current the water was lighter than 

 the selected value of a-i=27.2, this surface intersecting bottom beneath 

 the Banks half of the Labrador Current. 



An interesthig feature, which has an important bearing on the quan- 

 tity of berg ice in the Grand Banks region and whose full significance 

 cannot be determmed without further study, developed from the 

 shallow isentropic analysis of the first survey. The temperature- 

 salinity curves for the individual stations fell into three distinct groups. 

 One of these was the warm-water group having the characteristics of 

 Atlantic Current water and this was anticipated. That the colder 



