Elevation change measurements of the Greenland Ice Sheet

Repeated GPS measurements have been performed at the centre of the Greenlan d Ice Sheet since 1992. Results have shown that the ice sheet is essentiall y stable at this location, with GPS-determined strain and elevation change rates in good accordance with yearly snow accumulation and glaciological fl ow models. In a local ice cap in East Greenland (Geikie Plateau) repeated G PS, airborne laser altimetry and SAR interferometry have been used to study ice movements in the more climatically variable coastal zone, where meter- level annual elevation changes are possible due to the high precipitation. The paper outlines the surveys carried out, some preliminary results, and i ntercomparisons of GPS, laser altimetry and SAR techniques.