The impact of accumulation rate on anisotropy and air permeability of polar firn at a high-accumulation site
Abstract:The first three-dimensional properties of polar firn obtained by X-ray microtomography are used to study the microstructure of snow on a 15 m deep firn core from West Antarctica. The snow is found to undergo coarsening down to approximately 2.5 m depth before grain growth and densification become the prevalent mechanisms of microstructure change. In contrast to previous assumptions, distinct anisotropy of the ice and pore geometry is observed throughout the profile, with a maximum at 2.5 m depth. The air permeability and the degree of anisotropy vary with depth and can be linked to short-term changes in accumulation rate via the residence time for which a certain snow layer stays in the uppermost 2.5 m. Patterns of the degree of anisotropy and air permeability of buried polar firn are relative indicators of past accumulation rates.
Document Type: Research Article
Publication date: September 1, 2009
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- The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.
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