Introduction Gp Glasby

For the English schoolboy brought up in the 1950s, Antarctica was synonymous with Scott's last expedition and Sir Clements Markham's (President of the Royal Geographical Society 1893-1905) romanticized version of the British bluejacket manhauling his sledge to the Pole. Yet the paradox of this view is readily apparent on re-reading the accounts of this expedition and observing that Scott's ship, Terra Nova, almost capsized in 1910 in a storm two days out from Port Chalmers, New Zealand. The sea is the gateway to Antarctica and this sea is amongst the most remote, hostile and least studied of the world's oceans.

The region under study here, the Antarctic Sector of the Pacific (lying between Australia and South America and south of latitude 45°S), comprises about 6% of the earth's surface. To the south, the region is bounded by the western coast of the Antarctic Peninsula, Ellsworth Land (Bellingshausen Sea), Marie Byrd Land (Amundsen Sea), King Edward VII Land and Victoria Land (Ross Sea, including the Ross Ice Shelf). Scientific stations in this sector of Antarctica are Russkaya (U.S.S.R.) (Marie Byrd Land), McMurdo (U.S.A.) (Victoria Land) and Scott (N.Z.) (Victoria Land). There are few islands within this sector of the Southern Ocean. Balleny Island, Scott Island, Peter I Island and the islands off the western Antarctic Peninsula lie south of the Antarctic Convergence (or Polar Frontal Zone) but Macquarie Island and the New Zealand Subantarctic islands lie north of the Convergence. Hydrologically, the Antarctic region proper lies to the south of the Antarctic Convergence; the Subantarctic lies between the Subtropical Convergence and the Antarctic Convergence (Tchernia, 1980) (cf. Knox, 1987). Figure 1.1 shows the area under consideration.

The scientific importance of this region is derived from its central role in a number of areas; the reconstruction of Gondwanaland, the influence on Pacific climate and palaeoclimate and the formation of Antarctic Bottom Water, the high biological productivity and the proximity of the magnetic pole (cf. Laws, 1987; Parsons, 1987; Weller et al., 1987). As an example, the Western Boundary Current east of New Zealand transports roughly 20 x 106 m3 s1 of water northwards (i.e., about 16 times the total continental run-off, Baumgartner and Reichel, 1975) consistent with it being the principal supplier of deep water in the Pacific (Warren, 1981). Indeed, water from the Antarctic is thought to comprise 71% of the Pacific Ocean (Warren, 1971). For comparison, the average transport of the Antarctic Circumpolar Current is about 130 x 106m3 s"1 (Gordon, 1987; Whitworth, 1988). It has also been argued that the breakup of Pangea resulted in a sequence of climatic, erosional effects that have dominated the history of the earth's surface over the last 250 Ma (Hay, 1981,1984; Hay et al., 1981). For example, climatic changes in Antarctica have played a key role in determining the palaeoceanography of the world's oceans (Kennett, 1977,1980,1983; Loutit et al., 1983; Mercer, 1983; Ken-

Fig. 1.1. Schematic map showing the Antarctic Sector of the Pacific.

nett and von der Borch, 1986). In addition, it is now believed that the C02 content of the atmosphere is transferred to the deep sea through the nutrient content of high latitude surface water. The marked lowering of the C02 content of the atmosphere during the last glaciation was therefore markedly dependent on the chemistry of Southern Ocean waters (Toggweiler and Sarmiento, 1985; Wenk and Siegenthaler, 1985; cf. Sarnthein et al„ 1988).

Yet, it has only been in the last 30 years (since the International Geophysical Year, IGY, 1957-58) that serious attempts have been made to study this region scientifically and these have been spasmodic. Knowledge of this sector of the

Southern Ocean still lags behind that of the Antarctic continent. It has been said that the broad-scale geographical description of the world's oceans is more or less complete, apart from the polar waters and those of the South Pacific (Hempel, 1986). Eittreim, Cooper, and Scientific Staff (1984) considered the Antarctic continental margin to be geologically the least known continental margin. Similarly, Weller (1986) concluded that the Southern Ocean is the most poorly observed region on earth meteorologically with only a few buoys periodically deployed in the open ocean and in the pack ice; this situation is being improved by the use of satellites. In many ways, this lack of knowledge is understandable. The extreme remoteness of the region is emphasized by the fact that there is only one shipping route there (from Christchurch, New Zealand, to Scott Base, McMurdo Sound, a distance of 4,000 km). Its inhospitable nature is emphasized by the strong seas (particularly between 45°S and 50°S) and ice conditions further south (French, 1974; U.S. Navy, 1979).

The disappearance of Captain Robert Johnson (an American sealer) south of New Zealand in 1826 whilst seeking land between 60°S and 65°S, the collision of Erebus and Terror in front of an iceberg in 1842, the freezing in of Scott's ship Discovery in 1902-04 which necessitated a relief expedition being sent from England, the failure of Scott's ship Terra Nova to relieve the northern party in 1912, the involuntary drift of Shackleton's ship Aurora in the Ross Sea in 1915-16, the double capsize of David Lewis's yacht Ice Bird in 1972, the crushing and sinking of the German research vessel Gotland II off northern Victoria Land in 1981, the trapping of the Soviet research vessel Mikhail Somov in the ice in the Amundsen Sea in 1985, the sinking of the British vessel Southern Quest in the Ross Sea in 1986, the grounding and subsequent sinking of the Australian resupply ship Nella Dan at Macquarie Island in 1987, the sinking of the Argentinian supply ship Bahia Paraiso near Palmer Station on Anvers Island off the western Antarctic Peninsula in 1989 and the grounding of the Peruvian research ship Humboldt on King George Island off the western Antarctic Peninsula in 1989 all attest to the dangers of navigation in this region.

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