1999 Fiscal Year Final Research Report Summary
Study in relation with increase for the Greater Accuracy of Climatic and Environmental Information obtained from Ice cores
| Project/Area Number |
09480112
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Institute of Low Temperature Science, Hokkaido University |
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Principal Investigator |
NARITA Hideki Institute of Low Temperature Science, Hokkaido University, Associate Professor, 低温科学研究所, 助教授 (20001662)
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| Co-Investigator(Kenkyū-buntansha) |
SHOJI Hitoshi Kitami Institute of Technology, Professor, 工学部, 教授 (50201562)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Ice core / Past climatic and environmental reconstructions / Layer in firn core / Layer due to number concentration of clathrate hydrate / Electric conductivity measurement (ECM) / Cloudy band |
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| Research Abstract |
It has well known that the past climatic and environmental information obtained from Greenland ice cores is high resolution in time scale. However, error estimate of depth-age scale increases to 20 % or more at a bottom core. It is due to thinning and deformation of layer, and diffusion of material. Also, core recovered at inland area of Antarctica where is low accumulation rate is a lower resolution than in Greenland core. In order to increase for accuracy of climatic and environmental information (namely, time scale) of the core, a deformation test, ECM measurement and investigation of number concentration of clathrate hydrate were carried out. Flow disturbances have been shown to alter layer order in the lower part of the Greenland cores. 2-dimensional ECM signals on the sample became to disturb along the layers. Also, a mechanical test was carried out by use a sample that contains cloudy bands, but particular finding could not be made. On the other hand, it is considered that distribution of clathrate hydrate in space reflects air bubble distribution in shallower ice and pore space in firn, and therefore, has layer structure. Clathrate hydrate was accounted under microscope by use of thin section of the Dome Fuji deep core, Antarctica. The samples were selected 21 pieces from depth between 1200〜2400 m. The number concentration of clathrate hydrate changes periodically. The period means thickness of layer. And the measured values agreed with the annual thickness that was calculated by D-J model. The new method will be able to use for increase of accuracy of ice core time scale.
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