IDENTIFICATION OF SUBGLACIAL LAKES USING ERS-1 RADAR ALTIMETER

Radar-altimeter data from ERS-1 allow detailed topographic mapping of Antarctica to 82-degrees-S to be carried out, revealing several notable surface features. Among these is the large subglacial lake near Vostok which is mapped here in detail. The central part of the lake is found to have an exceptionally smooth surface with r.m.s. elevation variations of less than 0.2 m. A search for other large Antarctic lakes in the data is made based on the smoothness and low gradient of the surface. A number of other flat areas are identified with lake locations previously determined from radio-echo sounding observations. However, radar-altimeter observations show that a minimum lake size of 20 km is required for a surface above a lake to become flat. Numerous bowl-like features can be seen in the surface topography, and these may be associated with intermediate-sized subglacial lakes. It is determined that high spatial-resolution radar altimetery could be used to identify subglacial lakes greater than 10 km in lateral extent. Flat regions of the ice sheet are particularly useful as they may be used as height-reference surfaces to help fix the orbits of radar-altimeter satellites.