As a result, the ice driven from the Chuckchee Sea by a strong wind (counter to the northerly 

 current) into Bering Strait began to return to the Chuckchee Sea and the Chelyuskin drifted north- 

 ward against the wind 21 miles on the first day (24 hour period) and 30 miles on the second day. 



LITERATURE: 38, 77. 



Section 135. Drift Along the Isobars 



In making a careful study of the drift of the Sedov toward the end of 1938, I noticed that it 

 was always approximately parallel to the isobars on the ten day and monthly maps of atmospheric 

 pressure distribution over the Arctic Basin. 



As an example, below I give the following characteristic incidents from the drift of the Sedou. 



From 1 November 1938, through 1 February 1939, southeasterly winds prevailed in the re- 

 gion of drift. The ship drifted north- northwest. The high pressure region was situated approxi- 

 mately east-northeast of the Sedou at this time. However, in individual periods the wind changed 

 abruptly. 



Figure 132 shows the position of the isobars during the first ten days of December 1938. The 

 arrow on the map shows the general direction of drift of the Sedou for the ten-day period. It is 

 clear from the figure that the ship drifted exactly along the isobars. The high-pressure region was 

 situated above the Taimyr Peninsula at this time. The Sedou was under the influence of westerly 

 and southwesterly winds and thus it drifted northeast, leaving the high pressure region to the right 

 of it. 



In the third ten days of January 1939 (figure 133), the low-pressure region was situated above 

 the Kara Sea, while the high-pressure region was in the vicinity of the Pole. Correspondingly, the 

 Seduu drifted almost directly westward. 



Figure 134 shows a map of the mean monthly atmospheric pressure above the Arctic Basin 

 for January 1939. On this map, the double arrow shows the actual drift of tne Sedou for that 

 month. As we see, the drift coincides exactly with the isobar. 



Thus, my investigations established the following simple rule: above the deep sea, far from 

 the distorting influence of the coast, the pure wind drift of close ice follows the isobars, and is 

 such that the high-pressure region is to the right of the drift direction and the low pressure region 

 is to the left. 



These conclusions have been verified by Filippov, Petrichenko, Somov and others. 

 Petrichenko and domov, in particular; indicated that nine of the fourteen mean monthly and mean 

 ten-day charts which they examined showed complete agreement between the direction of drift and 

 the direction of the isobars. A subsequent examination of the charts which did not show agreement 

 between the isobars and the drift revealed that this lack of agreement was due solely to the approxi- 

 mate construction of the isobars in the region of drift of the Sedou. 



In what followed, I excluded the steady current from the drift of the Sedou and from an 

 analysis of 45 ten-day pressure maps. I found the average deviation of the true wind drift from 

 the isobar to be approximately 5°, which must be considered very satisfactory in view of the in- 

 accuracy of the isobar plots. The direction of the isobar taken for a comparison was based on a 

 synoptic map with an accuracy of about 10°. 



368 



