Applications of an Automated C-Axis Analyzer

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AbstractThis proposal requests support for applications of an automated system for ice fabric analysis. The system combines state-of-the-art digital imaging with computer-controlled polarizers to allow the orientation of all the grains on an ice thin section to be determined quickly and reliably. The method relies on a principle similar to computer aided tomography (CAT) used frequently for medical imaging. A plane containing the c-axis is determined for each of several orientations of the ice sample. A straightforward algorithm is used to find the unique direction of the c-axis which is consistent with the set of measured planes. The system will be integrated with the current capability at the National Ice Core Laboratory (NICL) for imaging and sizing ice grains to provide a facility which can completely characterize the fabric of ice thin sections. This facility will be available to anyone in the ice physics community who would like to analyze ice fabrics.The proponents will apply this instrument to specific issues relating ice flow and fabric. The project will take advantage of the vast store of samples from GISP2 which have been prepared but not analyzed due to time constraints. From this data set, the relationships between ice flow and softness indices determined from fabric will be investigated, and new analysis techniques to discern active process (e.g. grain formation) in the ice will be utilized. The presence of these processes has important implications for flow law exponents and the susceptibility of ice to deformation instabilities. These studies should point the way toward more accurate ice flow models, and also better diagnostics for analyzing ice core climate data.