184 MARIOISr AND GENERAL GREENE EXPEDITIONS 



to that of the parent currents. This is borne out by the fact that 

 such water has been found from the Tail of the Grand Banks to 

 the northern limit of the Atlantic Current and its direction of motion 

 verified by dynamic heights (page 136). Confirmation of this view 

 is to be found in the shape of the isohalines in similar latitudes in the 

 east and west longitudinal sections, which may be looked upon as 

 the result of mixing but which do not indicate the intermediate 

 water of Wiist. The difference between the intermediate water of the 

 Labrador Sea as designated in this paper and the North Atlantic 

 intermediate water of Wiist is threefold, embodying thickness, 

 direction and origin. 



The salinity maxima in the deep water is to be seen in all three 

 of the longitudinal sections. Below the deep water the bottom 

 water of minimum temperature is found. The bottom water is in 

 slow southward motion, hugging the American side of the Labrador 

 Basin, where bottom irregularities do not interfere, and following 

 the deeper channels in a tortuous path at levels above which bottom 

 formations project. 



THE INTERMEDIATE WATER 



It has been defined as occupying the more central parts of the 

 Labrador Sea below the surface water and above the deep water. 

 As might be expected, the intermediate water is a mixture, the salty 

 component of which is the deep water from below. The fact that 

 the salinity of the intermediate water is much lower than that of 

 the deep water points to fresh components around the sides of the 

 Labrador Basin and in the surface layers. The salinity gradient 

 in the more central surface layers of the Labrador Sea is steepened 

 during summer by the addition of fresh water from melting ice, 

 land drainage, and precipitation. This surface w^ater becomes rela- 

 tively light as it absorbs heat from the sun and therefore mixes 

 little with the intermediate Avater. But upon being cooled in winter 

 practically all of the summertime surface water in the region of 

 convection mixes and thereby freshens the intermediate water. A 

 greater and more enduring supply of fresh water comes from the 

 Labrador Current which from its northern source to the Tail of the 

 Grand Banks cabbels along its offshore margin to form intermediate 

 wat«r. A secondary supply of the fresh- water component of the 

 intermediate water arises from the East Greenland Current in the 

 eastern arm of the Labrador Basin. 



The determination of the low-salinity component of the inter- 

 mediate water by means of temperature-salinity correlations is made 

 difficult if not impossible due primarily to its wide annual tempera- 

 ture range. The extension of a line from the center of the group 

 of symbols representative of the deep water (fig, 146) through the 

 square-shaped symbol representing typical intermediate water, indi- 

 cates in a general way the relationship of the questionable com- 

 ponent with values of salinity lower than 34.88%o. 



One of the remarkable characteristics of intermediate water is its 

 thermal and haline homogeneity, the summertime temperature vary- 

 ing little from 3.2° C, whether it be off Cape Farewell or near the 

 head of the Labrador Basin as marked by the 3,000-meter isobath. 

 If a column of intermediate water be cooled to our lowest indicated 



