Determination of ice flow velocity in Svalbard from ERS-1 interferometric observations

Based on ERS-1 data recorded in autumn 1991, differential interferogrammes have allowed the determination of the ice flow of north-west Spitsbergen glaciers. The highest velocity of the d'Arodesbreen and the Fjortendejulibreen, observed in their equilibrium zone, was 3 cm and 6.6 cm per day, respectively. The large Kronebreen (700 km super(2)) is fed by two plateaux, Isachsenfonna and Holtedahlfonna. Along the longitudinal axis of Isachsenfonna, the velocity was near constant, around 20 cm per day over a distance of 20 km, while the velocity on Holtedahlfonna increased from near zero in the higher basin to 52 cm per day at 15 km to the calving front. The obtained velocities were in excess of 48% of the annual average velocity measured by GPS at three locations. Interferometric pairs were obtained at the end of the ablation period when the presence of subglacial meltwater can still lead a high velocity. These relatively high rates of velocity indicate that the basal sliding of Isachsenfonna and Holtedahlfonna is important and that the glacier sole must be at the melting point down to the front. The present temperature distribution in the glacier is still possibly influenced by a surge, which occurred 130 years ago.