V. KESCELIANEOUS 



A. Ice Conditions 



Ice conditions in the Antarctic areas covered during the present 

 cruise were minutely observed and reported upon from the time ice was 

 first entered in the Ross Sea on 12 Januarj'- 195U until the ATKA left 

 the ice in the Weddell Sea on 20 February 1955 • Quartermasters on 

 watch, under the supervision of the Chief Quartermaster and the 

 Navigator, made hourly ice observations from the bridge. These ob- 

 servations included ship's positionj distance gained, input distance, 

 number of forward turns of ship's propeller^ and nature and thickness 

 of the ice during the past hour. Observations reported on forms 

 furnished by the f^rdrographic Office and supplemented by some addi- 

 tional observations made by the civilian observer form the basis of 

 the ice track charts (figs. 7 through 10) and the report on ice 

 conditions • 



The ATKA entered the ice (70O08'S. 179°30'V/.) on 12 January 1955 

 at lUOO LST (fig« 7)« Surface water temperatures, which had been 

 gradually decreasing since leaving New Zealand waters, conanenced to 

 drop more rapidly after passing $9° S, where the surface water tempera- 

 ture was h3^ F. The Antarctic Convergence was passed between 62° and 

 63° S.,^and the surface water temperature dropped from 38"' to 35° F, 

 The first iceberg was sighted 6 miles off at 0930 LST on 12 January 

 at approximately 69° S, j icebergs had been noted on the radar screen 

 during the previous ni^t. 



The first pack 3cg encountered was con^osed of scattered brash 

 and rotten sriiiil floes and was of slight extent, open water being 

 regained after less than an hour's nin. Open water with only traces 

 of ice, a]l rott^en and easily transitted, continued until 72° S., 

 where brash was encountered, followed by small floes. Ice concentra- 

 tion increased shortly 'ihereafter and broken floes were passed through 

 for several miles, followed by a stretch of scattered ice which 

 continued until 73°l5 ' S, Ice concentration increased to a maximum 

 of 7/10 at 7hP S, From 7U° S. t« approximately 76%0' S., where the 

 open water of the Ross Sea was entered, scattered and broken ice was 

 traversed. Stretches of open water occurred frequently, and occasional 

 bergs, bergy bits, and growlers were present. 



The Ross Ice Barrier was sighted at about 173° W. early in the 

 morning of Ik January, From here to the former Bay of Whales, open 

 water with occasional bergs was foimd. This condition existed east- 

 ward to about hS miles beyond Little America, The break away of a 

 large mass of shelf ice, ?onetime be+^-ecn 19UB and the present time, 

 eliminated Discovery and Lindberg Inlets and the v;hole west side of 

 the Bay of VJha3.es, leaving an ice front of from 50 to 150 feet in 



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