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Bubble distributions as markers for deformation in polar ice

气泡分布作为极地冰变形的标志

基本信息

批准号：
274978142
负责人：
Dr. Johannes Freitag
金额：
--
依托单位：
Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/274978142?language=en
关键词：
Bubble distributions markers deformation polar

项目摘要

The analysis of air entrapped in bubbles in polar ice cores yields valuable information on the composition of the atmosphere during the last centuries. However, exploitation of this source of information is hampered by the lack of absolute dating tools linking the ice and the observed air to a certain period in time. Recent dating approaches rely on models which require a measure for the cumulated deformation of the ice as input. Up to now, there is no means for obtaining this information directly from an observed ice core. In the proposed project, we suggest using the locations of bubble centres as markers for the deformation. The main goal is to establish methods for the direct estimation of deformation parameters from the point pattern of bubble centres. To this end, our interdisciplinary research group will combine approaches from glaciology and point process statistics.The locations of bubble centres will be measured by means of core-scale X-ray-microfocus computer tomography on ice samples from different deep ice cores (EDC, EDML, Renland). The main idea of our analysis is based on the assumption that deformation introduces an anisotropy in the bubble centre patterns. Hence, estimates for the main axes and the degree of anisotropy may provide information on the main deformation directions and the strength of deformation. Although point process statistics is an active field of current research, suitably general methods for the anisotropy analysis of 3D point patterns are not available up to now. Hence, the glaciological problems posed in this project ask for advancements in the field of spatial statistics. In particular, methods for the estimation of preferred directions and deformation parameters in 3D point processes have to be found. Additionally, the presence of noise bubbles forming during relaxation of the ice must be taken into account. Using the estimated deformation parameters, models from glaciology for prediction of deformation parameters and dating of the ice will be validated and improved. The measured cumulated strain will give insights to the potential effect of microstructure (grain size, texture and fabric, impurity content) on the deformation behaviour of ice. The analysis of bubbly ice from the Renland ice core will provide information on deformation close to bedrock of a polar icecap for the first time.

对极地冰芯气泡中夹带的空气的分析，提供了关于上个世纪大气成分的宝贵信息。然而，由于缺乏将冰和观测到的空气与某个时期联系起来的绝对测年工具，这一信息来源的利用受到阻碍。最近的测年方法依赖于模型，需要测量冰的累积变形作为输入。到目前为止，还没有直接从观测到的冰芯中获得这些信息的方法。在建议的项目中，我们建议使用气泡中心的位置作为变形的标记。主要目标是建立从气泡中心的点图案直接估计变形参数的方法。为此，我们的跨学科研究小组将联合收割机结合冰川学和点过程统计学的方法，通过对不同深冰芯（EDC、EDML、Renland）的冰样品进行芯尺度X射线微焦点计算机断层扫描，测量气泡中心的位置。我们分析的主要思想是基于这样的假设，即变形在气泡中心图案中引入各向异性。因此，对主轴和各向异性程度的估计可以提供关于主变形方向和变形强度的信息。虽然点过程统计是当前研究的一个活跃领域，但到目前为止，还没有合适的通用方法用于三维点模式的各向异性分析。因此，在这个项目中提出的冰川学问题要求在空间统计领域的进步。特别是，在三维点过程中的首选方向和变形参数的估计方法必须找到。此外，在冰的松弛过程中形成的噪声气泡的存在必须考虑在内。利用估计的变形参数，将验证和改进冰川学的变形参数预测模型和冰的定年。所测得的累积应变将使人们了解微观结构（粒度，纹理和织物，杂质含量）对冰的变形行为的潜在影响。来自Renland冰芯的气泡冰分析将首次提供极地冰盖基岩附近变形的信息。

项目成果

期刊论文数量（7）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Variational Bayes approach for classification of points in superpositions of point processes

用于点过程叠加中的点分类的变分贝叶斯方法

DOI：
10.1016/j.spasta.2015.12.001
发表时间：
2016
期刊：
spatial statistics
影响因子：
2.3
作者：
T. Rajala;C. Redenbach;A. Särkkä;M. Sormani
通讯作者：
M. Sormani

A three-dimensional anisotropic point process characterization for pharmaceutical coatings

药物涂层的三维各向异性点工艺表征

DOI：
10.1016/j.spasta.2017.05.003
发表时间：
2017
期刊：
spatial statistics
影响因子：
2.3
作者：
H. Häbel;T. Rajala;C. Boissier;M. Marucci;K. Schladitz;C. Redenbach;A. Särkkä
通讯作者：
A. Särkkä

Estimating geometric anisotropy in spatial point patterns

估计空间点图案中的几何各向异性