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Volume 12, issue 2 | Copyright
The Cryosphere, 12, 609-625, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 21 Feb 2018

Research article | 21 Feb 2018

Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

Dorothée Vallot1, Jan Åström2, Thomas Zwinger2, Rickard Pettersson1, Alistair Everett3, Douglas I. Benn4, Adrian Luckman5,6, Ward J. J. van Pelt1, Faezeh Nick7, and Jack Kohler3 Dorothée Vallot et al.
  • 1Department of Earth Sciences, Uppsala University, Uppsala, Sweden
  • 2CSC – IT Center for Science, Espoo, Finland
  • 3Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway
  • 4School of Geography and Sustainable Development, University of St Andrews, St Andrews, Scotland, UK
  • 5Department of Geography, Swansea University, Swansea, UK
  • 6Department of Arctic Geophysics, UNIS, The University Center in Svalbard, Longyearbyen, Norway
  • 7Arctic Geology Department, University Centre in Svalbard, Svalbard, Norway

Abstract. In this paper, we study the effects of basal friction, sub-aqueous undercutting and glacier geometry on the calving process by combining six different models in an offline-coupled workflow: a continuum–mechanical ice flow model (Elmer/Ice), a climatic mass balance model, a simple subglacial hydrology model, a plume model, an undercutting model and a discrete particle model to investigate fracture dynamics (Helsinki Discrete Element Model, HiDEM). We demonstrate the feasibility of reproducing the observed calving retreat at the front of Kronebreen, a tidewater glacier in Svalbard, during a melt season by using the output from the first five models as input to HiDEM. Basal sliding and glacier motion are addressed using Elmer/Ice, while calving is modelled by HiDEM. A hydrology model calculates subglacial drainage paths and indicates two main outlets with different discharges. Depending on the discharge, the plume model computes frontal melt rates, which are iteratively projected to the actual front of the glacier at subglacial discharge locations. This produces undercutting of different sizes, as melt is concentrated close to the surface for high discharge and is more diffuse for low discharge. By testing different configurations, we show that undercutting plays a key role in glacier retreat and is necessary to reproduce observed retreat in the vicinity of the discharge locations during the melting season. Calving rates are also influenced by basal friction, through its effects on near-terminus strain rates and ice velocity.

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Short summary
This paper presents a new perspective on the role of ice dynamics and ocean interaction in glacier calving processes applied to Kronebreen, a tidewater glacier in Svalbard. A global modelling approach includes ice flow modelling, undercutting estimation by a combination of glacier energy balance and plume modelling as well as calving by a discrete particle model. We show that modelling undercutting is necessary and calving is influenced by basal friction velocity and geometry.
This paper presents a new perspective on the role of ice dynamics and ocean interaction in...