NO. 4 TEMPERATURK VARIATIONS IN THE NORTH ATLANTIC 2/ 



wind relations, that is to say, the distrilmtion of the atmospheric 

 pressure, exert a strong influence upon the variations in the sur- 

 face temperatures of the Gulf Stream. It is quite another ques- 

 tion as to whether these variations in the distribution of the air 

 pressure in a greater or less degree depend upon the variations of 

 the ocean currents and the masses of water brought on bv them. 



An important proof is furnished by Pettersson himself, for he 

 showed a tendency toward continuity during long intervals of 

 time in the variations of temperature both of the surface of the 

 sea and of the air, so that anomalies of the monthly mean tempera- 

 tures have exactly the same sign in a long succession of months. 

 However, twice during the year, in the months of May-June and 

 October-November there is a strong tendency to a break in this 

 continuity. He showed further that the march of the anomalies in 

 general from year to year shows a tendency to alternating rise 

 and fall of the mean temperatures. 



In later researches, " ( )n the probability of periodic and non- 

 periodic variations in the Atlantic Ocean currents and their rela- 

 tions to meteorological and biological phenomena" (1905, 1906), 

 Pettersson attempted to show that a great yearly pulsation occurs 

 in the Gulf Stream in the North Atlantic Ocean and in the warm 

 Atlantic currents of the Norwegian sea, whose flows experience a 

 strong minimum in the spring and a powerful maximum in autumn 

 and towards the end of the year. This, as we understand it, he con- 

 ceives to take place about simultaneously over the whole stretch 

 of the ocean between the Azores and the Bering Sea. The cause 

 of this pulsation Pettersson finds in the yearly melting of the ice 

 as well in the antarctic as in the northern oceans. He conceives 

 this action of the melting ice upon the different parts of the oceans 

 of the world to be propagated by a series of peculiar deep waves. 

 His conclusion appears to us in these points very doubtful and 

 difficult to understand. We cannot find that the trustworthy obser- 

 vations wdiich are at hand verify the assumption of a yearly pulsation 

 of the Gulf Stream such as he proposes.^ 



' Pettersson has devoted a long discussion (1905) to the dynamic conditions 

 in the Atlantic Ocean and the Indian Ocean and their relations to these varia- 

 tions. According to our view he has been misled by neglecting the rotation 

 of the earth. On this account he omitted to note that the dynamic sections with 

 their solenoids and their outward and inwardly directed forces, are able to 

 establish comparatively stationary conditions in the water-masses which have 

 their movement more or less at right angles to the direction of the sections 

 and which are in lateral equilibrium. As an example of this conception may 



