New insights in the ongoing surge of the Austfonna icecap

Abstract:

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.