Recrystallization regimes in an ice sheet - Towards a microstructure-based law of ice

• Applicant: Privatdozent Dr. Christoph Garbe
• Subject Area: Oceanography
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 198710168

A detailed understanding of the dynamics of polar ice sheets is essential for an accurate climate reconstruction and for the prediction of sea-level fluctuations. Today, the required simulations of ice movement are based on general, empirical material properties of ice. A more accurate description of these properties has to be extracted from the ice micro-structure over the entire ice sheet. This project will provide the necessary data-set for a quantitative parameterization of the entire grain boundary network based on microscopic image sequence analysis. Owning to the complexity and scope of the image data, specific and efficient methods of digital image processing (DIP) have to be developed and verified. Initially, the DIP methodology will be applied to the entire length of the East Antarctic EDML ice core, where the main emphasis will be the data reduction with regard to geometric parameters of grains and the evolution of grain boundaries. One goal is to document the extend to which the depth profiles of these micro-structural parameters are coupled with profiles of tracers and climate proxies in ice cores. The variability of subgrain boundaries with regard to the change of dislocation density represents a first indications of the depth dependence of ice viscosity and thus the rate of deformation. In this project, we will perform a semi-quantitative analysis of this aspect of micro-structural influence on ice dynamics.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• Participating Persons: Dr. Josef Kipfstuhl; Dr. Dietmar Wagenbach (†)