A continuum-mechanical model for the flow of anisotropic polar ice

TL;DR

This paper introduces the CAFFE continuum-mechanical model for anisotropic polar ice flow, incorporating fabric evolution and anisotropic flow law, validated through a case study of Antarctic ice core data.

Contribution

It presents a novel anisotropic flow law and fabric evolution equation integrated into a continuum mechanics framework for polar ice.

Findings

Model accurately describes ice flow behavior.

Applicable to real ice core data.

Simple enough for numerical implementation.

Abstract

In order to study the mechanical behaviour of polar ice masses, the method of continuum mechanics is used. The newly developed CAFFE model (Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor) is described, which comprises an anisotropic flow law as well as a fabric evolution equation. The flow law is an extension of the isotropic Glen's flow law, in which anisotropy enters via an enhancement factor that depends on the deformability of the polycrystal. The fabric evolution equation results from an orientational mass balance and includes constitutive relations for grain rotation and recrystallization. The CAFFE model fulfills all the fundamental principles of classical continuum mechanics, is sufficiently simple to allow numerical implementations in ice-flow models and contains only a limited number of free parameters. The applicability of the CAFFE model is demonstrated by a case study for the site of the EPICA (European Project for Ice Coring in Antarctica) ice core in Dronning Maud Land, East Antarctica.