DAVIS STRAIT AND LABRADOR SEA 133 



salted by a flooding of the Labrador Current past Cape Race. An 

 increase of the coastal supply accompanied by a dimunition in the 

 Labrador Current renews the coastal character of the central Grand 

 Banks reservoir. 



Another important movement of the waters over the Grand Banks 

 occurs when the border of the Gulf Stream floods in toward the 

 southwest slope bringing w^arm and salty water to the surface layers 

 there. 



Superimposed on the above primary circulation are the rotary 

 clockwise tidal currents and the annual temperature cycle, the range 

 of the latter of which is great in the shallow banks' column. (See 

 Smith, 1922, stations 140-142, for subsurface winter temperatures on 

 the Grand Banks; also Smith, 1924, p. 148.) The drift of icebergs in 

 over the Grand Banks has been described by Smith (1931). 



CROSS SECTIONS OF THE CURRENTS 



A total of seven velocity sections taken at fairly equal distances 

 along the eastern and southern slopes of the Grand Banks from the 

 forty-eighth parallel around to a point about 60 miles northwest of 

 the Tail are shown on figure 95. The profiles are based on the syn- 

 optic observations made from the United States Coast Guard cutter 

 General Chreene^ May 17-25, 1934. In addition, section R was taken 

 June 12-13 and section X, April 19-20. (For station table data, 

 see Soule, 1935.) In the aggregate these velocity profiles may be 

 compared with the map of the surface currents (fig. 117) and the 

 corresponding vertical sections of temperature and salinity (figs. 

 98 and 99). 



, A feature common to practically all of the velocity profiles (fig. 95) 

 ! is their division each into two bands of alternately directed current. 

 Reference to the horizontal and vertical sections of temperature and 

 salinity, as well as to the maps of the surface currents (fig. 117). 

 demonstrates conclusively that the inshore band represents Labrador 

 Current and the offshore band Atlantic Current. Unlike the sections 

 farther north, the Labrador Current is contained in a single band 

 centered over the steepest part of the slope. 



Particular attention is called to the decrease in the volume of the 

 Labrador Current between sections W and X, where on the latter 

 profile, stations 1603 to 1602, the westbound current was very di- 

 minutive. The vicinity of the Tail of the Banks represents, as stated 

 previously, the terminus of the Labrador Current. 



The axis of the cold current was centered over the steepest part 

 of the continental slope, and it had a mean draft of 950 meters. A 

 marked decrease in the draft of the Labrador Current was noted 

 •upon its crossing the Flemish Cap Ridge, but subsequently it deep- 

 ened (in places along the Grand Banks slope as great as 1,500 

 meters), yet not to the depths which it averaged upstream in the 

 American sector. The depth of the Atlantic Current on the other 

 hand was in most places probably greater than 1,500 meters. 



Section R. — It will be re<;alled that the net average volume of the 

 Labrador Current through the St. John's section, July 3-7, 1934 (p. 

 128), w^as 3.8 million cubic meters per second. The northernmost 

 profile in the Grand Banks section (sec. R, fig. 95), taken about 

 3 weeks prior to the St. John's, and 120 miles south of it, recorded 



