82 



BJ0RN HELLAND-HANSEN 



[rep. of the "MICHAEL SARS" NORTH 



20°C 



SON 



SON 



40N 



\5'C 



IO°C 



5°C 



o°c 



30N 



Fig. 30. Temperatures at 100, 400, 600 and 1000 metres below the 

 surface along 40° W. from 60° to 30° N. (the western North Atlantic). 



SON 



SON 



40N 



30N 



Fig. 31. Temperatures at 100, 400, 600 and lOUO metres below the 

 surface along 18° W. from 60° to 30° N. (the eastern North Atlantic). 



numerous serial observations have been made. Since these 

 charts were printed Professor Nansen and I have con- 

 structed some charts in greater detail. They are published 

 in "The Eastern North Atlantic", and two of theiri, for 400 

 and 1000 metres, are reproduced here in Figs. 28 and 

 29. We have made use of all the available modern obser- 

 vations, and have taken them as they are, without trying 

 to reduce them for possible temporal variations (cf. p. 59). 

 The "Michael Sars" stations are marked thus: ®. Figs. 28 

 and 29 show a number of differences from the correspond- 

 ing charts on p. 96* as far as details are concerned. The 

 new charts will certainly have to be corrected in many 

 particulars when more observations have been made. There 

 are still considerable areas where practically no stations 

 have been worked and the question is whether the condi- 

 tions here are complicated in much the same way as in 

 the localities where the stations lie comparatively close 

 together. 



It seems unnecessary to describe the temperature charts 

 in more detail. There are only one or two facts of a general 

 nature which seem worthy of special notice: 



The Great Atlantic Current forms, so to speak, a line 

 of demarkation at all levels down to 1000 metres or more. 

 We have only a limited number of observations from 

 quite a large region S. of Greenland, but we have reason 

 to believe that the whole of this part of the North Atlantic, 

 on the northern and western side of the current, consti- 

 tutes a cold area clearly distinct from a warm area on the 

 southern and eastern side. When we cross this important 

 current we pass from one 'world' to another as regards 

 temperatures, and the transition is very abrupt — probably 

 even more so than is shown in the charts on p. 96*. 



The conditions in the western part of the North 

 Atlantic are illustrated quite schematically in Fig. 30, which 

 shows the horizontal distribution of temperature along the 

 meridian of 40° W. from 60° to 30° N. Within a belt of 

 about 200 kilometres (or about 2 degrees of latitude) in 

 width we have a transition in temperature which is remark- 

 ably abrupt: at 100 metres below the surface about 10° C, 

 at 400 m. 8°, at 600 m. 5° and at 1000 m. 2° That there is 

 a division in a cold area to the north and a warm area 

 in the central parts of the North Atlantic is, of course. 



