DAVIS STRAIT AND LABRADOR SEA 187 



tion of salinity which gives the water below 2,000 meters and above 

 the bottom water its character. This particular water is best typified 

 by salinity maxima, the presence of which has already been pointed 

 out on several of the vertical sections of the Labrador Sea. The 

 temperature-salinity correlation in the heart of such masses is repre- 

 sented by the diamond-shaped symbols plotted on figure 146, page 185. 

 Their position with respect to the broken line on the figure supports 

 our previous statement, namely, that this which is called deep water ^^ 

 is a mixture of bottom water and Irminger-Atlantic water. 



The saltiest of the deep water, which typifies it, is formed during 

 the colder months of the year when cabbeling is assisted directly by 

 convectional cooling. Outside of the region of convectional sinking 

 to bottom, tlie deep water is found adjacently above the bottom water 

 throughout the year. Within the area of bottom-water formation in 

 winter the deep water becomes mixed with the intermediate water 

 and surface water from above. Following a resumption of positive 

 stability of the water column, the deep water re-forms in position 

 similar to that which prevailed prior to convection. 



THE BOTTOM WATER 



As shown by the temperature sections (figs. 140-145) it is not 

 possible that the bottom water of the Labrador Sea is supplied across 

 Davis Strait Ridge in summer. Examination of the transverse sec- 

 tions, figures 138 and 139, also show that in summer the cold parts of 

 the West Greenland and Labrador Currents are separated from the 

 bottom water by intervening water of higher temperature. The low 

 temperature of the bottom water, therefore, is either a result of win- 

 tertime conditions or is a relic of conditions which no longer exist. 

 That the latter is not true is demonstrated by figure 148, a vertical 

 longitudinal section showing the oxygen distribution from south of 

 50° N. latitude to Smith Sound. This section is a composite based 

 upon observations made on the Godthaah in 1928 and on the General 

 Greene in 1935. The location and identity of the stations upon which 

 it is based are shown on figure 135 where the course of the section is 

 indicated by the broken line. It will be noted that the GodthaaVs 

 oxygen values (that is, those for stations north of the break in the 

 profile lines) are consistently higher than those of the General Greene 

 by about 0.4 cubic centimeter per liter. It is evident from the con- 

 centration of dissolved oxygen that the Labrador Basin is an area 

 of active mixing and that there is no water in it but what has been 

 at the surface comparatively recently. It is logical, therefore, that if 

 the activity of the water were different in different years even the 

 deeper observations might give different results in different years. 



The relative values, however, are instructive and if the oxygeri 

 profile is superimposed on the temperature and salinity profiles it 

 is found that the General Greene's oxygen values of greater than 

 6.2 and the GodthaaVs oxygen values of greater than 6.7 cubic 

 centimeters per liter embrace what has been designated as the 

 intermediate water of the Labrador Sea. The shape of the 6.0 

 line in the southern part of the section and the lines in the region 



"Onr dp*>p water, which eventually drains out of the Labrador Basin into the North 

 Atlantic; embraces what Wlist (1935) has designated as North Atlanttc deep water. 



79920—37 13 



