New insights in the ongoing surge of the Austfonna icecap

Wednesday, 17 December 2014
Thomas Schellenberger1, Thorben Dunse1, Andreas Kääb1, Jon Ove Hagen1, Thomas Schuler1 and Carleen Reijmer2, (1)University of Oslo, Department of Geosciences, Oslo, Norway, (2)Institute for Marine and Atmospheric Research Utrecht, Utrecht, Netherlands
Basin-3, a major drainage basin of the Austfonna icecap in NE-Svalbard switched to full surge mode in autumn 2012 after a multiannual, stepwise acceleration of its northern branch. A time series of velocity maps from repeat TerraSAR-X acquisitions revealed a maximum speed at the terminus of >18 m d-1 around the turn of the year 2012. The frontal ablation of Basin-3 was estimated to 4.2±1.6 Gt a−1 between April 2012 and May 2013, tripling the total dynamic mass loss from the largest icecap in the Eurasian arctic.

Today, TerraSAR-X, Radarsat–2 and GPS data show that the surge is still ongoing. While the speed at the calving front dropped to 10 m d-1 until July 2014, areas further inland continued to accelerate after the climax, and 10 m d-1 were also measured ~20 km inland in summer 2014. This development will be further investigated by exploiting a time series of velocity maps based on Radarsat-2 Fine Beam data starting from July 2014, which will, other than the TerraSAR-X data, cover almost the entire fast flowing part of the basin. By combining both datasets we will extend the estimation of the frontal ablation and related sea-level rise contribution of the Basin-3 surge.