Subglacial water at the heads of Antarctic ice-stream tributaries

Subglacial water at the heads of Antarctic ice-stream tributariesThe onset of enhanced flow of ice in East Antarctica, which has been shown recently to lead to the development of ice streams (Joughin and others, 1999; Bamber and others, 2000), is associated in a number of cases with the presence of subglacial ``lakes'' .This observation shows that water is stored at the heads of enhanced-flow features, and provides an insight into (1) the potential role of subglacial water as a control on the flow of the interior ice sheet and, more generally, (2) the poorly known subglacial conditions of the Antarctic ice sheet.Recent ice-flux calculations indicate that enhanced-flow features, which drain ice to the ice-sheet margin, penetrate deep in the interior of the Antarctic ice sheet.We have compared the locations of known Antarctic subglacial lakes (Siegert and others, 1996; Dowdeswell and Siegert, 1999, in press) with these ice-flux calculations (Fig. 1).Several lakes lie at the onset of major enhanced ice-flow features such as those feeding into Byrd and David Glaciers in East Antarctica, and Ice Stream B in West Antarctica (Fig. 1).