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Texture of the Upper 1000 m in the GRIP and NorthGRIP Ice Cores

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/45437

Title: Texture of the Upper 1000 m in the GRIP and NorthGRIP Ice Cores
Authors: Svensson, Anders Browse this author
Durand, Gaël Browse this author
Mathiesen, Joachim Browse this author
Persson, Asbjørn Browse this author
Dahl-Jensen, Dorthe Browse this author
Keywords: ice core
ice crystal
texture
fabric
Greenland
Issue Date: Dec-2009
Publisher: Institute of Low Temperature Science, Hokkaido University
Citation: Physics of Ice Core Records II : Papers collected after the 2nd International Workshop on Physics of Ice Core Records, held in Sapporo, Japan, 2-6 February 2007. Edited by Takeo Hondoh
Journal Title: 低温科学
Journal Title(alt): Low Temperature Science
Volume: 68
Issue: Supplement
Start Page: 107
End Page: 113
Abstract: In this study we discuss new and published profiles of c-axis fabric and size distributions of a large number of crystals in the upper 1000 m of the Greenland GRIP and NorthGRIP ice cores as obtained with an automatic c-axis fabric analyzer. We show that in both cores the fabric is strongly anisotropic already just below the firn (about 110 m depth) with a degree of orientation around 30%. We determine the mean crystal area profiles which are somewhat contrasting to earlier findings based on manual measurements. The crystal size distributions are compared to a simple ID model which takes into account crystal growth and polygonization (rotation recrystallization). The model suggests that the crystal size distribution develops into a Bessel type distribution that differs from the commonly applied log normal distribution. Finally. we combine the fabric and microstructure results to determine the sub-grain boundaries in the GRIP samples. Both the size distribution model and the sub-grain study suggest that polygonization is significant already below the firn and that the physical processes governing the conventionally adapted 'normal grain growth' and 'polygonization' regimes are identical. The new measurements provide a dataset for ice sheet models that take into account the anisotropy of the Greenland ice sheet.
Description: I. Microphysical properties, deformation, texture and grain growth
Type: bulletin (article)
URI: http://hdl.handle.net/2115/45437
Appears in Collections:低温科学 = Low Temperature Science > vol. 68, Supplement Issue

Submitter: 低温科学研究所図書室

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