first of October the drift ice, which earlier had 

 been along the Siberian shore, may begin to 

 advance around Mys Dezhneva into the west- 

 ern side of Bering Strait. 



"Ice formation and growth proceed rapidly 

 in early October, and shipping is usually not 

 feasible north of Bering Strait after about 10 

 October. Prevailing north and northeast winds 

 pile large accumulations of floes against the 

 Siberian shore. 



"Between Point Barrow and Icy Cape drift 

 ice occasionally recedes from the coast, and 

 young ice which forms in the open water is 

 piled up in heavy masses along the shore when 

 the drift ice returns. Kotzebue Sound and Ber- 

 ing Strait are closed during middle and late 

 October by fast ice. By late October or early 

 November, ice closes North Sound. As the for- 

 mation of ice continues toward midwinter, the 

 ice limit gradually progresses southward until 

 at its maximum, navigation north of the 

 Pribilof Islands becomes impossible for ships 

 other than icebreakers." 



Cli7nate 



An estimate of the annual variation of 

 meteorological factors directly influencing sea- 

 air interaction in the eastern Chukchi Sea can 

 be obtained from atlases of average weather 

 conditions and from accumulated weather sta- 

 tion observations. The paucity of weather sta- 

 tions and reporting ships in this geographical 

 area make such an estimate inaccurate and 

 imprecise at best. 



Mean monthly values of surface wind (vec- 

 tor average) and temperature from volume 

 VIII of the Marine Climatic Atlas of the World 

 (U.S. Naval Weather Service Command, 1969) 

 reveal a relatively small range of seasonal 

 variation in the eastern Chukchi Sea. Observa- 

 tions taken over periods of 9 and 12 years from 

 Point Hope and Point Barrow respectively 

 (table 1), showed that winds were from the 

 NE-NNE at both coastal stations in all 

 months but January at Point Barrow (WNW) 

 and July and August at Point Hope (SE and 

 WNW) . The average wind speed at Point Bar- 

 row (<2i/2-5 kts) was lower than at Point 

 Hope (<2i/2-10 kts), but the patterns of var- 

 iation were approximately the same at the two 

 stations: lower speeds in January-February 

 and June-August. The monthly percentage 



frequency of winds of gale force (>34 kts, 

 table 2) was always less than 5 percent at 

 Point Barrow and exceeded 5 percent at Point 

 Hope only during November and December. 

 Conversely, the monthly percentage frequency 

 of light or gentle winds (<10 kts, table 2) 

 was lowest at both stations during October- 

 December, highest at Point Hope during May- 

 June, and highest at Point Barrow during 

 January-February and June. 



Table 1. — Monthly average wind velocity (vector aver- 

 age) and air temperature for Point Hope and Point 

 Barrow, Alaska. From Marine Climatic Atlas of the 

 World— Vol. VIII (U.S. Naval Weather Service 

 Command, 1969). 



Tabic 2. — Monthly average percent frequency of ob- 

 served winds equal to or greater than 34 kts and 

 equal to or less than 10 kts at Point Hope and Point 

 Barrow. From Marine Climatic Atlas of the World — 

 Vol. VIII. (U.S. Naval Weather Service Command, 

 1969). 



Month Percent frequency Percent frequency 



Winds >34 kts. Winds <10 kts. 



Point Hope Point Barrow Point Hope Point Barrow 



Jan. <B <5 



Feb. <5 <5 



Mar. <5 <5 



Apr. <5 <5 



May <5 <5 



June <B <5 



July <5 <5 



Aug. <5 <5 



Sept. <5 <5 



Oct. <E <5 



Nov. 10 <5 



Dec. >5 <5 



Prevailing winds at Point Barrow and off 

 Icy Cape (tables 3 and 4) showed a pattern 



