Chapter III 



THE CIRCULATORY SYSTEM AND TYPES OF WATER 



When our data collected during the summer of 1928 from the 

 Labrador Sea were substituted in Bjerknes' hydrodynamic formulae, 

 a general cyclonic circulation of the upper water layers (the tropo- 

 sphere) was revealed.* 



60 50 40 



Figure 5. — The system of circulation of tlie upper water layers (troposphere) in the 

 northwestern North Atlantic. 



This consists of a northward flow along the Greenland slope, the 

 West Greenland Current; a southward movement along the Ameri- 

 can side, the Baffin Land Current and the Labrador Current (cf . Riis- 

 Carstensen 1931, p. 5), and a northward set, the Atlantic Current 

 in the southern part of the Labrador Sea (fig. 5). The more cen- 



* The circulation of the upper water layers has been determined by reference to the 

 1,500-decibar surface. This common depth best served the observational data, several 

 stations offshore of the continental slopes not having been taken to greater depths than 

 1,500 meters. The computations indicated, however, that in certain regions, notably 

 along the Greenland slope, appreciable motion prevailed even at 1,500 meters. It should 

 be constantly borne in mind, therefore, that the Bjerknes' methods express results in terms 

 of comparative motion only. If the state of rest or motion on a selected datum plane 

 be incorrectly a.ssumed, an error is introduced and the results in terms of direction and 

 velocity of the currents consequently will be incorrect. In an area such as the north- 

 western North Atlantic, subject as it is to severe wintertime conditions and other 

 equally important suspected influences, it is wise to challenge constantly the validity 

 of assumptions required by the Bjerknes' method. 



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