The Stratospheric Circulation 



667 



Current the shelf forms the main path of the southward-flowing cold, weakly saline 

 water. Figure 314 shows this in a marked way and is characteristic of all the cross- 

 sections from Davis Strait to the Newfoundland banks. 



A calculated dynamic topography of the sea surface relative to that of the 1500- 

 decibar surface based on a dynamic evaluation of all the observational data (1928-35) 

 is shown in Fig. 315. This gives some idea of the current conditions in the very upper 

 layers, since it should correspond rather well to the absolute topography. The trough- 

 like depression of the water level between Greenland and Labrador stands out parti- 

 cularly well in this figure, with an even narrower continuation reaching southward as 

 far as the southern end of the Newfoundland Banks. The strong concentration of the 

 dynamic isobaths and a high coastal water level off south-west Greenland indicates 

 the West Greenland Current and off the north-east coast of America the Labrador 

 Current, while the strong rise from the southern peak of the Newfoundland Banks 

 towards the north-east is due to the Gulf Stream. According to the topographies of the 

 600- and 1000-decibar surfaces, the strength of the currents decreases very rapidly 

 with depth. In the region of the Labrador Current there are differences in water level 

 of about 30 dyn. cm at the sea surface while over the same distance the difference in sea 

 level at 600 decibars is only 3 cm and at 1000 decibars is not more than 1 dyn cm. 

 These currents are thus typical density currents and are confined to the top layers. 



Volume transports calculated from the velocity profiles for several different cross- 

 sections are given in Table 1 54 which also gives a rough budget for the water and heat 

 exchange amounts in the Labrador Sea. The pure gain in water is about 7-5 milhon 

 m^sec while the outflow along the Labrador Coast amounts to about 5-6 million m^sec. 

 Both values refer to a transport down to 1500 m depth. This gives a difference of 1-9 

 million m^/sec from which the authors assume that it is the water of the West Green- 

 land Current that sinks down to depths below 1 500 m and very probably flows out 

 of the Labrador Sea in the deepest layers. Figures for different seasons and for different 

 years vary considerably; for instance the transport of the Labrador Current was 

 1-31 milHon m^sec in 1930 and 7-60 in 1933. From this it must thus be concluded that 



Table 154. Exchange of water and heat in the Labrador Sea 

 {after Smith, Soide and Mosby) 



Exchange of 



Water 

 X 10® m^ sec-^ 



Heat 

 X 10» kg cal 



Inflow 

 West Greenland Current (average at Cape Farewell) 

 Baffin Land Current ..... 

 Hudson Bay discharge ..... 



Total . 



Outflow 

 West Greenland Current to Baffin Bay 

 Labrador Current (average South Wolf Island) 



Total 



50 

 20 

 0-5 



7-5 



10 



4-6 



5-6 



17-5 



-1-2 



0-5 



16-8 



0-5 

 14-6 



151 



