Simulating higher-order fabric structure in a coupled, anisotropic ice-flow model: application to Dome C

• Published in: Journal of Glaciology
• Main Authors: David A. Lilien, Nicholas M. Rathmann, Christine S. Hvidberg, Aslak Grinsted, M. Reza Ershadi, Reinhard Drews, Dorthe Dahl-Jensen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press
• Subjects: Anisotropic ice flow; ice-sheet modeling; recrystallization; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; East Antarctica; Antarc*; Antarctica; ice core; Ice Sheet; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2023.78; https://doaj.org/article/4f5e29f2070b4296988606c2ae08e9fa

Ice-crystal fabric can induce mechanical anisotropy that significantly affects flow, but ice-flow models generally do not include fabric development or its effect upon flow. Here, we incorporate a new spectral expansion of fabric, and more complete description of its evolution, into the ice-flow model Elmer/Ice. This approach allows us to model the effect of both lattice rotation and migration recrystallization on large-scale ice flow. The fabric evolution is coupled to flow using an unapproximated non-linear orthotropic rheology that better describes deformation when the stress and fabric states are misaligned. These improvements are most relevant for simulating dynamically interesting areas, where recrystallization can be important, tuning data are scarce and rapid flow can lead to misalignment between stress and fabric. We validate the model by comparing simulated fabric to ice-core and phase-sensitive radar measurements on a transect across Dome C, East Antarctica. With appropriately tuned rates for recrystallization, the model is able to reproduce observations of fabric. However, these tuned rates differ from those previously derived from laboratory experiments, suggesting a need to better understand how recrystallization acts differently in the laboratory compared to natural settings.