Ice Fabric Development with a New Fabric Evolution Model

Wednesday, 17 December 2014
Michael Hay, University of Washington Seattle Campus, Seattle, WA, United States and Edwin D Waddington, University of Washington, Seattle, WA, United States
Crystall orientation fabric in polar ice sheets has a strong influence on ice flow due to the plastic anisotropy of ice. The evolution of crystal fabric is driven by strain-induced grain rotation, as well as recrystallization. Most fabric-evolution models ignore or parameterize many of the physical processes involved, or are valid only for highly parameterized fabrics. Here, we describe a new fabric model that incorporates a more-realistic treatment of the physics involved. The model includes connectivity information between grains, with grains exchanging mass and interacting with their neighbors. The model treats dynamic recrystallization, polygonization, grain rotation, and other processes. We validate the model against thin-section data from the WAIS divide ice-core. By initializing the model with a number of fabrics generated by resampling shallow thin sections (with replacement) we show that a large proportion of fabric variability seen in deeper thin sections is stochastic, arising both from initial conditions and from the variability inherent in fabric development.