DAVIS STRAIT AND LABRADOR SEA 179 



West Greenland Current as it enters the Labrador Sea. The idea 

 of cabbeling was first published by Witte (1910) and depends 

 upon the nonlinear relation between the temperature and the den- 

 sity of sea water. Because of this nonlinear relation and the prac- 

 tically linear salinity-density relation an adiabatic mixture of 

 two waters of equal density but of ditfering temperature and salin- 

 ity will have a greater density than its components. It is evident 

 that, in nature, horizontally adjacent bodies of water will have 

 very nearly equal densities. When such adjacent waters are of 

 differing temperature and salinity characteristics their intermixture, 

 with its attendant increase in density, will result in a partial sinking 

 of the mixture to an equilibrium density level from which level 

 further sinking is possible through further mixture with adjacent 

 water of dissimilar temperature and salinity characteristics. The 

 fact of the presence of two water masses of dissimilar types in juxta- 

 position is in itself an indication of the presence of horizontal cur- 

 rents. The intermixture of two such water masses along their border 

 may be aided at and near the surface by wave action but will be 

 effected by the horizontal motion which transported the water there, 

 not only near the surface but in deeper water as well. As a natural 

 result, then, there will be a decided and even preponderant horizontal 

 component to this mixed water as it sinks. Such is our conception 

 of cabbeling as it occurs in the regions under discussion. The ver- 

 tical component of motion as initiated by cabbeling is in many parts 

 of the Labrador Sea during the colder months of the year accelerated 

 by convectional chilling, but the latter factor is quite independent 

 of the former. 



It may be noted here that areas such as the boundaries of the 

 Irminger- Atlantic Current and the Labrador Current have been called 

 polar fronts by some authors. This term, borrowed from meteor- 

 ology, may be considered synonomous with the mixing zones de- 

 scribed in this paper if it is apphed not only to surface phenomena 

 but to subsurface current margins as well. 



STATION DATA 



In the following paragraphs the vertical distribution of the velocity 

 of the currents, the temperature, and salinity, will be discussed with 

 reference to two transverse and three longitudinal vertical sections, 

 the geographical locations of which are shown on figure 135. 



VELOCITY PROFILES OF THE STRATOSPHERE 



A statistical investigation of the dynamic height computations for 

 the 1935 post-season cruise of the General Greene^ where all stations 

 were occupied to near the bottom, indicated from a consideration of 

 departures of differences of anomalies of dynamic heights from aver- 

 ages for 500-meter depth intervals, that in the Labrador Sea the 2,000 

 meter surface is probably close to the surface of most nearly motion- 

 less water. On the assumption that 2,000 meters represents the depth 

 of motionless water velocity profiles for the complete sections, Reso- 

 lution Island to Fiskernaessett {Godfhaah stations 18 to 28) and 

 South Wolf Island to Cape Farewell {General Greene stations 2026 



