[barnes] ISOTHERMAL LAYER OF LOW TEMPERATURE 77 



Table of Conductivity (Temp. 25°C.) 



In the Strait of Belle Isle -04806 



Nearly abeam Belle Isle East end • 04865 



40 miles east of Belle Isle -04986 



70 



100 

 200 

 260 

 462 



•05047 

 •05214 

 •05235 

 •05257 

 •05257 



Across the polar current east of Belle Isle Strait, the salinity 

 rises steadily until the waters of the Gulf Stream are entered. This 

 lower salinity, which is indicative also of a lower density, must be 

 brought about by the melting of the polar ice and the consequent 

 mixture of the fresh water with the Southern waters. The lower 

 density is observed through Belle Isle Strait and in many parts of the 

 Gulf. Dr. Dawson's density determinations of the Gulf waters 

 are very interesting and show a low surface density which increases 

 regularly with depth, down to about 40 or 50 fathoms. At greater 

 depths the density becomes uniform and practically equal to that 

 of the open Atlantic. These various densities are very important 

 when considering any system of ocean circulation, inasmuch as they 

 show greater differences than are produced by mere change oftemper- 

 ature. It must be that the polar current tends to over-ride the Gulf 

 Stream, in spite of the great difference in temperature between the 

 two currents. This no doubt is responsible for the streaky character 

 of the border of these two currents. It is difficult to see otherwise, 

 why the polar current does not suddenly dip down below the warmer 

 Gulf Stream, leaving a much sharper line of separation along the 

 southern border. Assuming the surface density of the Labrador or 

 polar current to be the same when it meets the Gulf Stream as it is 

 off the mouth of Belle Isle Strait, then comparison of the densities of 

 the two currents shows for 



Labrador Current 1 • 0230 



Gulf Stream 1-0257 



Difference -0027 



The difference of density of the sea-water due to temperature alone 

 would be, assuming the temperature of the polar current to be 32 °F. 

 and that of the Gulf Stream to be 60°F, 



1-02818-1-02567= -00251 

 a smaller value than that due to difference of salinity alone. It seems 

 to me that these differences in density must considerably modify the 



