Evolution of glacier microstructure

The microstructure of ice evolves with depth and time in an ice sheet. This evolution of microstructure depends on the ice flow field, temperature, and impurity content. The flow field, in turn, depends on glacier microstructure, leading to feedbacks that produce layered variations in microstructure that are related to climate and flow history. Velvet Ice is a comprehensive study of the relationship between ice microstructure, impurities, and ice flow and their connection to climate history for the West Antarctic Ice Sheet (WAIS) Divide ice core site. Our objective is to understand how the evolution of ice microstructure with time and stress is related to impurity content, temperature, and strain rate and how the spatial variability of ice microstructure and its effect on ice flow affects our interpretation of climate history in the WAIS Divide ice core. This project combines a detailed study of ice crystal orientation fabrics obtained through scanning electron microscope based Electron Backscatter Diffraction (EBSD) with measurements of borehole deformation made using logging instruments. We incorporate and build on data collected by other WAIS Divide researchers, including borehole sonic velocity measurements, borehole optical dust log measurements, borehole temperature, crystal size and shape, and ice core chemistry.

This work is funded by the National Science Foundation, Antarctic Glaciology Program.

Faculty contact: Rachel W. Obbard