1996 Fiscal Year Final Research Report Summary
Microphysical properties of ice cores and paleoenvironment signals
| Project/Area Number |
06402066
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
HODOH Takeo Hokkaido Univ., Inst.of Low Tem.Sci., Prof., 低温科学研究所, 教授 (60109494)
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| Co-Investigator(Kenkyū-buntansha) |
MAE Shinji Hokkaido Univ., Fac.of Eng., Prof., 工学部, 教授 (80022672)
KOUCHI Akira Hokkaido Univ., Inst.of Low Tem.Sci., Prof., 低温科学研究所, 教授 (60161866)
KAWAMURA Toshiyuki Hokkaido Univ., Inst.of Low Tem.Sci., Assistant Prof., 低温科学研究所, 助手 (50091434)
NARITA Hideki Hokkaido Univ., Inst.of Low Tem.Sci., Associate Prof., 低温科学研究所, 助教授 (20001662)
FURUKAWA Yoshonori Hokkaido Univ., Inst.of Low Tem.Sci., Associate Prof., 低温科学研究所, 助教授 (20113623)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Ice core / Climate change / Paleoenvironment / Air composition / Clathrate hydrate / X-ray diffraction / Raman spectra |
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| Research Abstract |
We have carried out ice core studies on Dome F cores and Vostok cores in this three years project. Main results obtained are summarized as follows.
(1) Density profile and accumulation conditions : Precise density profile along the Dome F shallow cores was measured by a new measurement system using x-rays. Annual variation of the densities was successfully found by this system. The density profile obtained gives us very important data for better understanding of the past accumulation conditions and densification processes, and for modeling of gas diffusion processes in the firn layr.
(2) Number density of clathrate hydrates : A beautiful correlation between a dalta D profile and a profile of the number densities of clathrate hydrates was obtained by the Vostok cores doun to 3000m depth.
(3) Fractionation of air molecules : The method to determine the mole fraction of air molecules included in the clathrate hydrates was developed by taking anisotropic nature of the Raman spectra into account. By this method, a clear picture of the molecular fractionation process was obtained.
(4) Formation process of clathrate hydrates : We have developpd a theoretical model for the transition process of air bubbles to clathrate hydrates, and obtained useful formulas to describe the processes involved.
(5) Structural variation of ice : We found inceasing of the high energy peak of the lattice vibration spectra with depth in Vostok cores, but did not in other cores. The results show a very long term aging effect on the peak.
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