VI. ICE CONDITIONS 



A. General 



Ice conditions in the Antarctic were recorded aboard ATKA, EASTWIND, 

 GIACIER, and BURTON ISLAND, annotating percent concentration, thickness, 

 age, topography, and snow cover. These data are portrayed by conven- 

 tional ice symbols along ships' tracks. Widths of tracks illustrated 

 vary according to visibility conditions at time of observation. 

 Figures 18 through 22 illustrate ice conditions in the Western Ross Sea 

 from December through Marchj Figure 23, for the Amundsen and 

 Bellingshausen Seas during February; and Figure 2k, along the western 

 coast of the Palmer Peninsula during March. 



B. Geographic Area 



1. Ross Sea Area 



Aboard GLACIER on 9 December 1959* the first icebergs and 

 grovlers vere sighted at 60 a 30'S, 177 *E (Fig. 18). The pack, varying 

 from five- to eight-tenths concentration of average thickness four to 

 five feet, was entered shortly thereafter. At about 7 i «- S> the ship 

 entered open water on 12 December and remained in this until reaching 

 Kainan Bay. GIACIER and ARNEB departed Hainan Bay on 18 December for 

 McMurdo Sound, transiting open water to the vicinity of Beaufort Island. 

 Grounded icebergs blocked passage of the ships between Beaufort Island 

 and Cape Bird. GLACIER left McMurdo 9 January for New Zealand, passing 

 through intermittent patches of one and five-tenths concentration to 

 about 65 °S; no ice was sighted north of this. 



ATKA also entered the ice pack on 9 December 1959> reporting three- 

 and four-tenths coverage of young and slush ice at approximately 

 65*30'S (Fig. 19). The concentration increased to seven- tenths of 

 winter ice at 70 °S. Thickness of this ice varied from three to five feet 

 with large floes and fields predominating. From 70°S to the vicinity of 

 Franklin Island, the ship operated in open water, except for a patch of 

 nine- tenths winter and young ice at 72 *S. McMurdo Sound was filled with 

 eight-tenths concentration of five-foot bay ice from 13 through 15 

 December. This ice extended north midway between Beaufort Island and 

 Franklin Island. 



On 1 January i960, ATKA sailed northward to conduct oceanographic 

 stations in the vicinity of Scott Island. After passing through five- 

 and eight- tenths ice in McMurdo Sound (Fig. 20), open water was reached 

 at about 76*S, near Franklin Island. Ice was again encountered at 

 71 *S, 177 *E, where three- and four-tenths of block and brash were re- 

 ported. From 71° to 66 "S, and in the vicinity of Scott Island, con- 

 centrations varied from four- to seven-tenths of block, brash, and slush 

 with an average thickness of three feet, during the period 3 through 5 



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