LABRADOR CURRENT 



Any discussion of tlie Labrador Current is 

 clouded by lack of a precise definition of its 

 properties along its entire course. Current re- 

 gimes have traditionally been identified either by 

 their velocity or water property (T-S relation- 

 ship) characteristics. The Labrador Current has 

 variously been described in Ice Patrol publica- 

 tions as a cold, narrow, southward flowing cur- 

 rent with the high velocity core located on the 

 continental slope of the Grand Banks between 

 the 200-nieter and 2000-nieter isobaths. Alter- 

 nately, the Labrador Current has l)een defined by 

 an 8-year mean T-S curve from data collected 

 along the eastern slope of the Grand Banks which 

 ranges from — 1°C, 33.3%o near the surface to 

 4°C, 34.9Voo at depth (Cheney and Soule, 1951). 

 \either attempt at a definition takes into account 

 the conditions of the origins of this current nor 

 its split into two separate southward flowing 

 components, shelf and slope, and a third east- 

 wardly flowing oceanic component as the flow 

 out of the Labrador Sea approaches the northern 

 slope of the Grand Bank. Likewise, neither de- 

 scription deals with the fate of the current after 

 it reaches the Tail-of-the-Bank. Further com- 

 plication arises from the observation that the 

 maximum velocity core of the Labrador Current 

 does not coincide with either the greatest tem- 

 perature or salinity gradient (Kollmeyer, Wol- 

 ford, and Morse, 1966). 



Following the precedent of previous authors, 

 when the discussion centers on the dynamic 



topography charts in this report the Labrador 

 Current is represented by the closely packed 

 dynamic height contours which roughly parallel 

 the bathymetric contours of the eastern slope of 

 the Grand Banks, and includes the continuation 

 of the contours at the point of reversal of a 

 portion of the contours near the Tail-of-the-Bank 

 which continue in a northeasterly direction until 

 they leave the survey area. It is acknowledged 

 tliat by this time mixing with the North Atlantic 

 Current has taken place such that there are sig- 

 nificant changes in the current's water mass prop- 

 erties. Furthermore it is understood that this is 

 only one branch of the original Labrador Cur- 

 rent, although probably the main one, and that 

 other definitions of the Labrador Current may 

 show that water exiting southward from the 

 Labrador Sea may have other fates. 



When the discussion in this report entails the 

 measured volume transports, the XPORT com- 

 puter program description is used which differ- 

 entiates between two types of volume flow 

 independent of direction of flow : Cold Core (i.e., 

 Labrador Current) which is water less than 2°C 

 and 34.3°/f,„ and Warm W^ater (i.e., mixed water 

 and North Atlantic Current) which is water 

 greater than 2°C and 34.3°/oo. While it is under- 

 stood that these definitions are not as precise as 

 one might wish, they serve the purpose of stand- 

 ardizing computations and permit comparison 

 with discussions in previous Ice Patrol reports 

 that used similar schemes. 



