Surface meltstreams on the Amery Ice Shelf, East Antarctica

A topographic map of a 120 km by 20 km section of the Amery Ice Shelf, East Antarctica, mapped with the global positioning system (GPS) in the spring of 1995, revealed two long, shallow troughs in the ice-shelf surface. Smooth features coinciding with these troughs appeared in a synthetic aperture radar image acquired 18 months earlier. ERS-1 altimeter waveform sequences and backscatter measurements along repeat satellite ground tracks across the same section of the Amery Ice Shelf, for the 1993-94 summer, exhibited a dramatic change over a 2 km sector between 30 January and 2 February 1994. The change is consistent with the presence of liquid water on the ice-shelf surface, located in the deeper of the two troughs. A time series of special sensor microwave/ imager brightness temperatures over the Lambert Glacier-Amery Ice Shelf region for the same period has sharp maxima on 5 January and 21 January 1994. These maxima are interpreted as the melting events leading to the meltstream observed in the altimeter data 25 days later.