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Study in relation with increase for the Greater Accuracy of Climatic and Environmental Information obtained from Ice cores

与提高从冰芯获得的气候和环境信息的准确性有关的研究

基本信息

批准号：
09480112
负责人：
NARITA Hideki
金额：
$ 4.16万
依托单位：
Institute of Low Temperature Science, Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

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.

众所周知，从格陵兰冰芯中获得的过去气候和环境信息在时间尺度上具有高分辨率。然而，在底部岩心，深度年龄尺度的估计误差增加到20%甚至更多。这是由于层的变薄和变形，以及材料的扩散。此外，在积累速率较低的南极洲内陆地区恢复的岩心分辨率低于格陵兰岛的岩心。为了提高岩心气候环境信息（即时间尺度）的准确性，进行了变形试验、ECM测量和笼形水合物数浓度调查。流动扰动已被证明改变了格陵兰岩心下部的层序。样品上的二维ECM信号沿层产生扰动。另外，用含有浑浊带的样品进行了力学试验，但没有特别的发现。另一方面，认为包合物水合物在空间上的分布反映了冰层较浅的气泡分布和冰层孔隙空间的分布，具有层状结构。利用南极富士巨蛋深岩心薄片，在显微镜下对笼形物水合物进行了研究。样品选取深度在1200 ~ 2400 m之间的21块。笼形物水合物的数浓度呈周期性变化。周期表示层的厚度。实测值与D-J模型计算的年厚度基本吻合。该方法可用于提高冰芯时间尺度的精度。