NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 29 



Especially Otto Pettersson's first cited work, '' On the Relation 

 Between Hydrographic and Meteorological Phenomena " have led 

 to several valuable investigations on the change of ocean circula- 

 tion and climate. As the most important among them we must 

 mention at this point that of Prof. Dr. Wilhelm Meinardus. 



After he had investigated the " Dependence of the Winter Cli- 

 mate in Aliddle and Northwestern Europe on the Gulf Stream " 

 (1898) and the dependence between the variations in the air tem- 

 perature on the Norwegian west coast at Christiansand in the 

 autumn and the crop production in north Germany in the following 

 summer. Meinardus. particularly in his work. " On the variations 

 of the North Atlantic circulation and their consequences" (1904 

 and 1905), studied the dependence between the temperature varia- 

 tions in the ocean on the coast of Jutland and Norway and the 

 distribution of air pressure over the North Atlantic Ocean. As an 

 indicator o'f the last-named relation he used the air pressure dif- 

 ference in the successive years between Toronto, Canada, and Ivig- 

 tut in southwest Greenland for the years 1875 to 1900. Also that 

 between Ponta Delgada on the Azores and Stykkisholm, Iceland, 

 for the years 1866 to 1900, and also between Copenhagen and Styk- 

 kisholm in the years i860 to 1909. Furthermore, he compared 

 these results with the ice transportation by the Labrador current 

 near Newfoundland. 



Meinardus starts with the assumption that variations in the atmos- 

 pheric pressure differences between Greenland and Iceland on the 

 one side, and Canada, the Azores and Copenhagen on the other, 

 correspond to similar alterations in the circulation in the ocean. 

 Great air pressure differences correspond to increased ocean circu- 

 lation and vice versa. He further supposes that when the Atlantic 

 circulation in this way is increased. " it produces on oppsite shores 

 of the Atlantic opposite influences on the transportation of heat by 

 the ocean currents. By the acceleration of the Gulf Stream the tem- 

 perature of the western coasts of Europe is increased, while by a 

 simultaneous acceleration of the Labrador current its transportation 

 of ice is increased and most probably the European temperatures are 

 thereby diminished. \\'ith decreased water circulation opposite 

 tendencies prevail." Meinardus takes no account of the displace- 

 ments in the positions of the great air pressure maxima and minima 

 or on the variations in their intensity. It can easily happen for 

 example that the pressure minimum over the northern ocean may 

 be particularly well-marked without being indicated by pressure dif- 



