Articles | Volume 10, issue 6
The Cryosphere, 10, 3071–3089, 2016

Special issue: International Partnerships in Ice Core Sciences (IPICS) Second...

The Cryosphere, 10, 3071–3089, 2016

Research article 21 Dec 2016

Research article | 21 Dec 2016

Strain localization and dynamic recrystallization in the ice–air aggregate: a numerical study

Florian Steinbach1,2, Paul D. Bons1, Albert Griera3, Daniela Jansen2, Maria-Gema Llorens1, Jens Roessiger1, and Ilka Weikusat1,2 Florian Steinbach et al.
  • 1Department of Geosciences, Eberhard Karls University Tübingen, 72074 Tübingen, Germany
  • 2Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Germany
  • 3Departament de Geologia, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain

Abstract. We performed numerical simulations on the microdynamics of ice with air inclusions as a second phase. Our aim was to investigate the rheological effects of air inclusions and explain the onset of dynamic recrystallization in the permeable firn. The simulations employ a full-field theory crystal plasticity code coupled to codes simulating dynamic recrystallization processes and predict time-resolved microstructure evolution in terms of lattice orientations, strain distribution, grain sizes and grain-boundary network. Results show heterogeneous deformation throughout the simulations and indicate the importance of strain localization controlled by air inclusions. This strain localization gives rise to locally increased energies that drive dynamic recrystallization and induce heterogeneous microstructures that are coherent with natural firn microstructures from EPICA Dronning Maud Land ice coring site in Antarctica. We conclude that although overall strains and stresses in firn are low, strain localization associated with locally increased strain energies can explain the occurrence of dynamic recrystallization.

Short summary
How glaciers or ice sheets flow is a result of microscopic processes controlled by the properties of individual ice crystals. We performed computer simulations on these processes and the effect of air bubbles between crystals. The simulations show that small-scale ice deformation is locally stronger than in other regions, which is enhanced by bubbles. This causes the ice crystals to recrystallise and change their properties in a way that potentially also affects the large-scale flow properties.