Articles | Volume 10, issue 2
The Cryosphere, 10, 497–510, 2016
The Cryosphere, 10, 497–510, 2016

Research article 03 Mar 2016

Research article | 03 Mar 2016

Modelling calving front dynamics using a level-set method: application to Jakobshavn Isbræ, West Greenland

Johannes H. Bondzio1, Hélène Seroussi2, Mathieu Morlighem3, Thomas Kleiner1, Martin Rückamp1, Angelika Humbert1,4, and Eric Y. Larour2 Johannes H. Bondzio et al.
  • 1Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 2Jet Propulsion Laboratory – California Institute of Technology, Pasadena, CA, USA
  • 3Department of Earth System Science, University of California Irvine, Irvine, CA, USA
  • 4Faculty 05: Geosciences, University of Bremen, Bremen, Germany

Abstract. Calving is a major mechanism of ice discharge of the Antarctic and Greenland ice sheets, and a change in calving front position affects the entire stress regime of marine terminating glaciers. The representation of calving front dynamics in a 2-D or 3-D ice sheet model remains non-trivial. Here, we present the theoretical and technical framework for a level-set method, an implicit boundary tracking scheme, which we implement into the Ice Sheet System Model (ISSM). This scheme allows us to study the dynamic response of a drainage basin to user-defined calving rates. We apply the method to Jakobshavn Isbræ, a major marine terminating outlet glacier of the West Greenland Ice Sheet. The model robustly reproduces the high sensitivity of the glacier to calving, and we find that enhanced calving triggers significant acceleration of the ice stream. Upstream acceleration is sustained through a combination of mechanisms. However, both lateral stress and ice influx stabilize the ice stream. This study provides new insights into the ongoing changes occurring at Jakobshavn Isbræ and emphasizes that the incorporation of moving boundaries and dynamic lateral effects, not captured in flow-line models, is key for realistic model projections of sea level rise on centennial timescales.

Short summary
We implemented a level-set method in the ice sheet system model. This method allows us to dynamically evolve a calving front subject to user-defined calving rates. We apply the method to Jakobshavn Isbræ, West Greenland, and study its response to calving rate perturbations. We find its behaviour strongly dependent on the calving rate, which was to be expected. Both reduced basal drag and rheological shear margin weakening sustain the acceleration of this dynamic outlet glacier.