2001 Fiscal Year Final Research Report Summary
NMR Imaging of 3-D Snowpack Structures
| Project/Area Number |
11640423
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Hokkaido University |
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Principal Investigator |
NARITA Hideki Hokkaido Univ., Inst.of Low Temp. Sci., Asso. Prof., 低温科学研究所, 助教授 (20001662)
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| Co-Investigator(Kenkyū-buntansha) |
KOSE Katsumi University of Tsukuba, Inst. Of Applied Physics, Asso. Prof., 物理工学系, 助教授 (60186690)
SONE Toshio Hokkaido Univ., Inst. of Low Temp. Sci., Assi. Prof., 低温科学研究所, 助手 (10222077)
YAMADA Tomomi Hokkaido Univ., Inst. of Low Temp. Sci, Asso. Prof., 低温科学研究所, 助教授 (50002100)
HACHIKUBO Akihiro Kitami Insututute of Technology, Dep. of Civil Eng., Asso. Prof., 未利用エネルギー研究センター, 助教授 (50312450)
TAGUCHI Yoshihiro Chuo Univ., Fac. of Sci. and Eng., Asso. Prof., 理工学部, 助教授 (30206932)
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| Project Period (FY) |
1999 – 2001
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| Keywords | NMR imaging / Snow pack / 3D-Visualization / 3D structures / Ice spheres / Depth-hoar crystals / しもざらめ雪 / しまり雪 |
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| Research Abstract |
Microstructure of the snow pack should be better understood because it affects the mechanical and physical properties of snow. Thin sections and plane-surface sections are currently used to investigate. However, they give only two-dimensional information ; therefore, a large number of operations are necessary to reconstruct the three-dimensional structure. In this study we have developed a NMR imaging technique to visualize and quantify the 3D structure of snow pack.
Because the NMR signal from the ice was very weak, the air spaces in the snow were filled with dodecane doped with iron acetylaetonate C12H26, which has a good infiltration property and a low freezing point (about -12℃). Thus, the NMR images the space occupied with dodecane instead of ice particles. The 3D images were obtained with a homebuilt NMR imaging system using a 4.74-T superconducting magnet. The result of test imaging of dodecane showed 0.5 to 2 hours were needed to obtain the one 3D image, and hence we developed a specimen cooling system to keep the temperature below 0℃. This system has a double-pipe cylinder made of acrylic plastic with outer diameter of 40 mm and inner diameter of 20 mm through which cold air was passed. Two types of snow were prepared : ice spheres of about 3-mm diameter and depth-hoar crystals. In particular, because the ice spheres are sufficiently large and uniformly sized, they were ideal for test imaging. 3D microscopic images were obtained successfully ; the image matrix was 128^3 and voxel size was 0.2 mm^3. We could recognize the 3D structure of the packed ice spheres clearly by viewing from various angles and cross sections.
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