The Sedov 's drift parallel to itself is by no means surprising. The Fr am and the station 

 "North Pole" in exactly similar fashion experienced no rotation, although they too described fan- 

 tastic zigzags under influence of the wind. Such a three-fold concurrence demonstrates with suffi- 

 cient conclusiveness that in the drift are great ice areas participating simultaneously which moves 

 in the same direction, obeying winds of the same strength and direction. 



Finally, we also find confirmation of this condition in the surprising similarity of the drifts of 

 the Sadko and Lenin caravans in the Laptev Sea in 1937 to 1938, the drifts being different only in 

 the details. Both caravans, being subjected to the same winds, repeated the same zigzags. 



During this type of movement, which was generally parallel to itself, the Sedou occasionally 

 made a turning movement relative to the general direction. The amplitude of such turns from July 

 through December 1939 was up to 23°. These turns may be explained not only by local causes con- 

 nected with formation of local polynyas and water openings, but also by more general causes. 



Thus, for example, these turns could be caused by the fact that the ice which moves from the 

 New Siberian Islands towards Greenland as it drifts southwest pushes its southern edge into the 

 northern end of Sevemaya Zemlya, Franz Joseph Land and Spitzbergen, thus making the ice turn 

 counter-clockwise. In drifting northwest, the ice runs into the more massive polar ice which is 

 located in the region north of Franz Joseph Land, approximately above the 86th parallel. 



LITERATURE: 31, 62, 70, 72, 77. 



Section 150. Atmospheric Pressure Over the Arctic Basin 



We have seen that the drift of ice is determined by the winds and by the effect of the earth's 

 rotation, and that in the final result it proceeds along the isobars and with a speed inversely pro- 

 portional to the distance between them. Thus, the distribution of atmospheric pressure which de- 

 termines the direction of the air currents is reflected in a most decided fashion on the general and 

 local circulation of ice. 



The most important centers of atmospheric action for the arctic are: 



1. The Iceland low - a deep barometric depression located in the northern part of the Atlantic 

 Ocean, slightly south of Iceland. From this center, a trough of low pressure stretches to the north- 

 east, extending in winter to Sevemaya Zemlya and in autumn even to the New Siberian Islands. 



This trough is formed by the northeast movement of cyclones which have formed on the southern 

 periphery of the Icelandic low. 



2. The Aleutian low - situated in the northern part of the Pacific Ocean. It is sharply defined 

 in the winter, while in the summer it is replaced by an area of slightly increased pressure. This 

 low has considerably less influence on the Arctic Basin than the Icelandic low and its sphere of in- 

 fluence extends for the most part, only into the Chuckchee Sea. 



3. The East Siberian high - extremely sharp defined in the winter. In January its center is 

 situated at approximately 60° north, 120° east. In summer this high is completely eliminated and 

 in its place is located an area of decreased atmospheric pressure. 



425 



