DAVIS STRAIT AND LABRADOR SEA 137 



ably been missed since the ice-scouting duties of the Ice Patrol have 

 never afforded time to explore depths in the Grand Banks sector 

 greater than 1,500 meters. Michael Sars stations 69 and 70 at the 

 Tail of the Grand Banks (Hellaiid-Hansen, 1930) do indicate, how- 

 ever, the southerly continuation of the deep water described in 

 chapter VIII. 



A striking feature of the profiles, best ilhistrated on sections T, U, 

 and W (figs. 98 and 99) where the isotherms and isohalines surface 

 to 300 meters on the scale of the drawings lie nearly vertical, is the 

 abutment of Arctic and Atlantic water. A similar distribution of 

 the temperature and the salinity, but not quite so well defined, has 

 been noted in the Greenland sector, where two different types of 

 water flank each other. These convergences illustrate cabbeling 

 (p. 175), the angle being greatest in the zone of greatest changes in 

 temperature and salinity. The temperature convergence, most 

 clearly marked in the surface layers during the colder part of the 

 year, is commonly known as the cold wall. (See 10° C, isotherm on 

 profiles T, U, and W, fig. 98.) If the temperature profiles be com- 

 pared with the corresponding ones of velocity (fig. 95), it will be 

 found that the cold wall lay an average of 20 miles offshore of the 

 boundary between the Labrador and Atlantic Currents. This con- 

 dition is believed to be more apparent than real; observations taken 

 at closer intervals across the two streams would probably reveal a 

 coincidence between the distribution of temperature, salinity, and 

 resulting motion. 



Along the boundary of the Atlantic and Labrador Currents, as 

 shown by several of the intersecting sections of density (Smith, 1926, 

 p. 30), relatively light water often collects in the surface layers to 

 depths of 20 or 30 meters. Wliether or not these shallow pools are 

 the result of an indraft initiated by intense cabbeling along the 

 density wall is a question which remains for future investigation. 



Temperature-salinity correlation curves for the sections in the Grand 

 Banks sector (fig. 100) correspond in general features to those (figs. 

 65 and 66) for the American sector. The flatter part of the curve is 

 again representative of the Labrador Current, while the end portions 

 beyond points I and II are typical of the Labrador Current's prin- 

 cipal components. Point I, with an approximate temperature value 

 of —1.5° C, and a salinity of about 33.32%o (slightly warmer and 

 saltier than typical Arctic wat^r in the American sector) represents 

 typical Arctic water in the Grand Banks sector. Continuation of 

 the curves (fig. 100) upward and to the left is representative of the 

 correlation in banks and coastal water. Continuation of the curves 

 from point II upward to the right gives graphs which parallel those 

 representative of the correlation found in Atlantic water. Naturally 

 these given lines lie to the left of a curve representative of the axis 

 of the Gulf Stream since the Grand Banks sector embraces only the 

 northern margin of that current system. 



ANNUAL VARIATIONS 



In order to show the variation in the position of the Labrador 

 Current and the Atlantic Current in the Grand Banks sector, a series 

 of 20 dynamic topographic maps, 1000-0 decibars (figs. 102-121) are 

 appended to this chapter. The station table data upon which they 



