Ice Islands, 1967

Résumé

Five large ice islands broke away from the Ward Hunt Ice Shelf between 19 August 1961 and 18 April 1962. The largest of these was WH-5, which drifted through Nares Channel and eventually broke up. The Polar Continental Shelf Project (PCSP) has been following the movements of the four remaining ice islands WH-l, WH-2, WH-3, and WH-4 since the summer of 1963. By 1967 two of these islands, WH-3 and WH-4, had drifted out of the effective range of PCSP aircraft but the U.S. Naval Oceanographic Office "Birds Eye" flight, 3 August 1967, sighted an ice island (probably WH-4) at 71°55'N, 133°50'W. Previous to this the same organization located what was thought to be WH-3 at 73°28'N, 128°30'W on 3 April 1967. ... Of the four ice islands making up the WH group, WH-3 and WH-4 are the easiest to identify. WH-3 has a "suture" line running across one end of the ice island. WH-4 has a Jamesway hut near one corner and 10 empty 45-gallon gasoline drums lying in the shape of an "L" near the opposite corner. Because of the difficulties of positively identifying WH-l and WH-2, PCSP proposed a program to set up markers on both these islands. ... Although it is possible to estimate the rate and direction of ice island movement, it is important periodically to locate and identify particular islands. It was hoped that the drums set out by PCSP would assist the various sea ice reconnaissance groups to identify specific pieces of ice as they moved in the waters of the Arctic. Reports from the "Birds Eye" flights suggest that the specific patterns of drums are readily picked up by radar as well as the human eye, and that the drums will prove to be a very effective means of identifying ice islands.