272 



POLAR PROBLEMS 



appearing minimum (caused by a thrust of Antarctic water), which, 

 however, hardly is expressed in the temperature^ but only in the salin- 

 ity — the polar and subpolar seas have cold water above and below and 

 warmer water in a massive intermediate layer. From the magnitude of 

 this polar mesothermy in comparison with the slight inversion at looo 

 meters in the warmer seas, it is evident how much more potent the 

 influence of the tropics is than that of the Antarctic. Mesothermy 

 also takes place in the Arctic Sea and is there due to the Gulf Stream, 



Fig. 2 — Section showing temperature of the water in the southernmost part of the Atlantic Ocean, 

 at the northern end of Weddell Sea. Isothermals (temperature in C.) are shown as full lines, isohalines 

 (salinity in thousandths) as broken lines. The mesothermic layer is ruled. Vertical exaggeration, 125 

 times. The location of the vertical temperature series a, b, c, d, and e is shown on the inset map. 

 (From PI. 2 of work cited in footnote 5.) 



as the warmer water of this current pushes in between the cold masses 

 on the surface and on the bottom. The cold reaction which corre- 

 sponds to that inversion is, on the other hand, to be found only in a 

 restricted area south of Lightning Channel, which cuts through the 

 Faeroe-Iceland submarine ridge. Thus even in the north the in- 

 fluence of the tropics predominates. 



In the accompanying figures, I have represented the mesothermic 

 stratification as it has been found so far in the vicinity of the Antarctic. 

 Figure i, for the southern Indian Ocean, is based on the observations 

 of the Gauss expedition;^ Figure 2, of the southernmost South At- 



3 G. Wiist: Zweiter Bericht iiber die ozeanographischen Untersuchungen [der Deutschen At- 

 lantischen Expedition], Zeitschr. Gesell. fiir Erdkimde zu Berlin, 1926, pp. 231-250; reference on p. 

 249. 



^ Erich von Drygalski: Ozean und' Antarktis: Meereskundliche Forschungen und Ergebnisse 

 der Deutschen Siidpolar-Expedition 1901-1903 (Deutsche Siidpolar- Expedition 1901-1903, herausg. 

 von Erich von Drygalski, Vol. 7, Part V, pp. 387-556), Berlin and Leipzig, 1926, pp. 473 ff. and 

 PI. 8. 



