TEMPEBATUKE OF THE SURFACE WATBHS OF THE ATLANTIC OCEAN 



especially in the higher latitudes, and also the value for 

 the zone average may change considerably. Taljle 1 

 shows the vahics calculated from the curves for every 

 fifth degree of latitude and for the differences between 

 these values. 



Table 1. — Annual average of the surface lent peralure for every fifth 

 degree of latitude of the Atlantic Ocean (i^) and of the combined 

 oceans (tw)- 



Figure 2 shows the two-degree zonal averages for 4 

 selected months — February, May, August, and Novem- 

 ber. These averages clearly indicate the excess of 

 warmth of the North Atlantic Ocean. 



•c «o*s 



Figure 2. — Two-degree zonal averages of surface temperatures 

 of the Atlantic Ocean for the months of February, May, 

 August, and November. 



The South Atlantic is warmer only in the southern 

 summer (February). Even in the zonal averages, the 

 influence of the Labrador Current, as well as that of the 

 "Cold Wall," is clearly recognizable. The average 

 temperature of the whole ocean, calculated on the basis 

 of the zone values with regard to the number of two- 

 degree fields supplied with observations for 70° N. to 

 60° S., is 16.8° C. 



It is necessary to relate the main features of the 

 horizontal temperature to the scheme of the synthesis 

 of the ocean on the basis of the vertical distribution of 

 the temperature and of the saline content. This scheme, 

 which Defant '° has outlined, provides for the introduc- 

 tion of boundary strata {Grenzschichten), especially 

 between the troposphere and the stratosphere, and has 

 proved extremely fruitful. It has already been used 

 several times, most recently by Sverdrup " '^ and 

 Deacon '^ '* in the treatment of the data of the Dis- 

 covery Expedition." It also served in the treatment 

 of the synthesis of the hydrosphere of the Atlantic 

 Ocean within the limits of this present work as a basis 

 for classification. "^ '° The most outstanding of these 

 boundary strata is the one between the troposphere 

 and the stratosphere. Although its position cannot be 

 established accurately everywhere, especially in the 

 higher latitudes, because of the lack of clear criteria, 

 nevertheless, its sectional plane with the surface of 

 the ocean stands out clearly at many points. Its 

 course is distinctly reflected in the distribution of the 

 surface temperature wherever the latter, from the 

 point of view of the poles, increases quickly in a sharp 

 gradient. This process occurs in the South Atlantic 

 Ocean at about 50° S. and in the Drake Passage at 

 about 60° S. Between these two positions lies the ant- 

 arctic polar front, and the antarctic convergence, or 

 Meinardus Line, as Schott '^ called it. Because of 

 the lack of observations, the exact positions for a 

 similar rise in temperature in the north cannot be 

 followed, but it begins approximately at about 35° N., 

 runs eastward parallel to the American coast, and 

 curves northward at Newfoundland and on the east 

 coast of Canada. Not until it reaches the east coast 

 of Greenland is it found again, and then between the 

 cold East Greenland Current and the offshoots of the 

 Gulf Stream. As a result of the complicated distribu- 

 tion of water and land, the polar front is not so uni- 

 formly built up in the north as it is in the south where 

 it crosses the ocean diagonally in an east-west direction. 

 This difference is well expressed in figure 3, which 



"> A. Defant, Die systematisdie Erforschung des Weltmeeres. Zeitschr. d. Qes. t. 

 Erdkunde. Berlin. Jubil.-Sonderband. Berlin, 1938. 



See also current charts by H. H. F. Meyer in O. Wust. Der Ursprung der 

 Allanlischen Tiejenwaxser: also A, Defant, Dynamisclie Ozeanographie. Berlin, 1929. 

 See also H. Thorade, Die Stratosphare unde Traposphdre des Atlantisclien Ozeans. 

 .\nnalen d. Hydro^raphie. Berlin, 1937. 



n H. U. Sverdrup, On Vertical Circulation in the Ocean Due to the Action of the 

 Wind With Reference to Conditions Within the Antarctic Circumpolar Currents. Dis- 

 covery Rep. Vol. Vn, Cambridge, 1933. 



" H. U. Sverdrup, Wie entsteht die antarklische Komergemf Annal. d. Hydrogr. 

 Bd. 62. Berlin, 1934. 



" G. E. R. Deacon, A General Account of the Hydrology of the South Atlantic Ocean. 

 Discovery Rep. Vol. VII, Cambridge, 1933. 



'* G. E. R. Deacon, Die Nordgrenzen antarktischen und subantarktischen Wassers im 

 Weltmeer. Annal. d. Hydrogr. LXII. Hamburg, 1934. 



's A. Defant, Die Troposphdre des Attantischen Ozeans. Wiss. Ergebnisse d. 

 Deutsch. Atlant. Expedition a. d. Forschungs- und VermessungssohiH Meteor 

 Bd. VI. Teil I. Berlin, 1936. 



i« O. Wiist, Die Stralosphare des Attantischen Ozeans. Wiss. Ergebnisse d. Deutsch. 

 Atlant. Expedition a. d. Forschungs- und Vermessungsschifl Meteor. Bd. VI. 

 Teil 1. Berlin, 1936. 



" G. Schott, Qeographie des Atlantischen Ozeans. 2. Aufl. Hamburg, 1926. 



