72 



The arrows could be drawn in almost all cases, however, and not just 

 where the 750-decibar levels were computed, for where the latter 

 values were absent higher decibar levels between the stations could 

 be compared. 



The station groups when worked out showed densities, and hence 

 current sets and drifts by computation, that were quite logical in all 

 cases when a few stations, obviously in error, were thrown out of the 

 picture. Nothing like an ideal detailed current map could be made, 

 but a number of the stations were so grouped that the width of the 

 €old south-flowing Labrador current was determined at several places 

 and times along the southern half of the eastern edge of the Grand 

 Banks. 



The nearest approaches to real current maps made were sets 3 and 5 

 that are shown in Figures 16 and 18. In these two groups there was 

 enough of a network of stations to permit the construction of dynamic 

 contour lines. These lines actually represent the relief of the average 

 level of the sea surface with wave motion eliminated, and are drawn 

 connecting points that are the same height above a base level that in 

 each case was taken as the deepest sea hollow on the map. When 

 contour lines are drawn in, a much more accurate picture of the oceanic 

 circulation can be formed than where scattered stations, or even good 

 but distantly separated lines of stations at right angles to the Banks, 

 are used. 



The currents flow as shown by the arrows in directions parallel to 

 the contour lines. The water, as stated above, always tries to flow 

 down the hill, but there is no outlet at the bottom and earth rotation 

 continually deflects it, so it has to flow along just about parallel to the 

 contours with the higher water on the right hand in the northern 

 hemisphere when facing in the direction of flow. 



Sets 3 and 5, studied with and without contoul" lines, give such 

 radically different pictures of the circulation that it can now be defi- 

 nitely stated that the only distribution of stations that will give re- 

 sults of practical value to the ice patrol is a thick checkerboard network 

 of stations. This is partly on account of the confused eddying conditions 

 in the waters off the Tail of the Grand Banks. In an area where there 

 was less turbulence, where the currents flowed along with less mixing 

 and interaction — as is probably the case farther southwest in the Gulf 

 Stream, and farther north in the Labrador current — a single line of 

 stations taken at right angles to the supposed stream flow would be of 

 value. 



The two contoured current maps give just a hint of the complexity 

 and irregularity of the currents that prevail about the Tail of the Banks. 

 The picture of the circulation that would be gained by studying the 

 dynamic relations of the line of stations, as 905 to 910 in one of these 

 figures, would give a simple Labrador current and offshore Gulf Stream 



