Item: Three-dimensional mr microscopy of snowpack structures
Title: Three-dimensional mr microscopy of snowpack structures
Proceedings: 2002 International Snow Science Workshop, Penticton, British Columbia
Authors: Toshihiro Ozeki, Katsumi Kose, Tomoyuki Haishi, Seitarou Hashimoto, Shun-ichi Nakatsubo, Kouichi Nishimura, Hokkaido University ofEducation, lwamizawa, Japan, Institute of Applied Physics, University of Tsukuba, Tsukuba, Japan, MR Technology Co
Abstract: A magnetic resonance microscopy technique was developed to visualize and quantify the three-dimensional structure of snowpack. Because the NMR signal from the ice was very weak, we looked at the air space in the snow that was filled with dodecane doped with iron acetylaetonate. Four types of snow were tested: ice spheres, large rounded poly-crystals, small rounded mono-crystals and depth hoar crystals. Among these materials, the depth hoar crystals were the best for the test imaging, since they were sufficiently large and have anisotropic structures. A specific specimen-cooling system was developed to keep the temperature below 0 °C. In the experiments 0.5 to 2 hours were necessary to accumulate the signals enough to obtain a 3D micro-image; the image matrix 1283, voxel size 200 1Jlll3 or the image matrix 256, voxel size 120 um. The 3D structures of snow were investigated viewing from various angles and cross sections. Comparison with the 2D data using the conventional thin section method was also carried out and it was attested that the MR microscopy could be a powerful tool to reveal the microstructure of snowpack.
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Keywords: snow crystal structure, magnetlc resonance imaging, three-dimensional structure, dodecane
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