Flow dynamics near the bottom of Greenland ice sheet revealed by the Summit ice core analysis

峰会冰芯分析揭示了格陵兰冰盖底部附近的流动动力学

• 批准号: 08454127
• 负责人: SHOJI Hitoshi
• 金额: $ 4.86万
• 依托单位: Kitami Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454127/
• 关键词: ice core; ice sheet flow; cloudy band; global environment; Summit core

A long-term environmental record on the Earth can be obtained from Greenland ice sheet studies. A continuous deep ice core was retrieved at Summit, Central Greenland by GRIP in 1992. Core analysis reveals abrupt climatic fluctuations existed during Eemian/Sangamon interglacial period. However, a possibility that this is an artifact caused by complica ted flow behaviors near the ice sheet bottom is also pointed out.This study revealed the following findings under an international research collaboration with other GRIP members.1) Mechanical property studies showed the following results.・Ice sheet flow is dominated by crystallographic anisotropy of ice in plastic deformation processes.・ Impurity concentration type/level affects the formation process of crystal orientation distribution characteristics associated with the stess field in the ice sheet.・ Differential flows in a small scale exist near cloudy bands.2) A new flow law is obtained by using laboratory test results of core samples for ice sheet dynamics considerations. The application of this law to the Summit position shows that ice flow just above the complicated bottom tends to be unstable easily and the flow is quite sensitive to the bottom topography.3) A detailed core analysis on the Summit core, considering the above ice flow behaviors and other core data shows that at least one abrupt climatic change during Late Eemian is real. Further studies are planned and proceeded by performing the North GRIP project.

对格陵兰冰盖的研究可以获得地球上的长期环境记录。1992年，GRIP在格陵兰中部的Summit获得了一个连续的深冰芯。岩芯分析揭示了Eemian/Sangamon间冰期气候的突变。然而，也指出这可能是冰盖底部附近复杂的流动行为造成的假象。这项研究在与其他GRIP成员的国际研究合作下揭示了以下发现。1）力学性能研究显示了以下结果。·冰盖流动受冰在塑性变形过程中的结晶各向异性控制。·杂质浓度类型/水平影响与冰盖应力场相关的晶体取向分布特征的形成过程。·在云带附近存在小尺度的差异流动。2）利用室内冰芯试验结果，从冰盖动力学的角度出发，得到了一个新的流动规律。对萨米特冰芯的详细分析表明，晚Eemian期至少有一次气候突变是真实的。通过执行North GRIP项目，计划并进行进一步的研究。

项目成果

Castelnau, O.: "Anisotropic behavior of GRIP ices and flow in Central Greenland." Earth and Planetary Science Letters.(in press).

Castelnau, O.：“格陵兰岛中部的握冰和水流的各向异性行为。”

D.Dahl-Jensen: "Flow properties of the ice from the Greenland Ice Core Project ice core:The reason for folds?" Journ.Geophys.Res.102・C12. 26,831-26,840 (1997)

D. Dahl-Jensen：“格陵兰冰芯项目冰芯的流动特性：褶皱的原因？”Journ.Geophys.Res.102・C12（1997）。

S.J.Johnsen: "The δ^<18>O record along the GRIP deep ice core and the problem of passible Eemian" Journal of Geophys. Res.(印刷中).

S.J.Johnsen：“GRIP 深冰芯的 δ^<18>O 记录和可通 Eemian 的问题”地球物理学研究杂志（正在出版）。

S.J.Johnsen: "The <SO>^^^<18> record along the Greenland Ice Core Project deep ice core and the problem of possible Eemion climatic instability" Journ. Geophys. Res.102・C12. 26,397-26,410 (1997)

S.J.Johnsen：“格陵兰冰芯项目深层冰芯的<SO>^^^<18>记录以及可能的Eemion气候不稳定问题”地球物理学杂志Res.102・C12（1997）。

Miyamoto, A.: "An attempt at deformation tests of deep ice core samples containing cloudy bands." Proc.NIPR Symp.Polar Meteorol. Glaciol.11. 87-93 (1997)

Miyamoto, A.：“尝试对含有云带的深冰芯样本进行变形测试。”