20th century behaviour of Drygalski Ice Tongue, Ross Sea, Antarctica

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Abstract
Drygalski Ice Tongue is the floating seaward extension of David Glacier, a large outlet glacier draining from Talos and Circe Domes of the East Antarctic ice sheet. Several explorers mapped and described Drygalski Ice Tongue in the early years of the 20th century and, although this information does not allow detailed interpretation of ice-tongue behaviour, it is clear that from 1900–12 it was a significant feature extending 65—75 km from the coast. More detailed information has been compiled from aerial photographs and satellite images. In December 1956, the ice tongue was about 110 km long. By December 1957, a major calving event had occurred and the outer 40 km of the ice tongue had broken away. This is the only major 20th century calving event identified, and it may have occurred during a violent storm that affected the Ross Sea area in mid-June 1957. By 1960, further minor ice loss had occurred but, since that time, Drygalski Ice Tongue has maintained the same shape. In January 1993, the ice tongue was 95.8 km long and at its terminus was flowing at 880 900 m a-1. Drygalski Ice Tongue is an important regulator of the size of the Terra Nova Bay polynya. The average size of the Polynya has varied from nearly 2000 km2, in 1956, to 650 km2 in 1957. This has a. significant impact on sea-ice production in the Ross Sea. In 1956, about 115 km3,) of sea ice would have been produced, sufficient to cover 30%of the Ross Sea area with a 1 m thickness of sea ice.