Collaborative Research: Deformation of the Arctic Sea Ice Cover: Formation and Action of Failure Zones

合作研究：北极海冰盖的变形：破坏区的形成和作用

• 批准号: 0328605
• 负责人: Erland Schulson
• 金额: $ 30.18万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0328605&HistoricalAwards=false
• 关键词: Collaborative; Research; Deformation; Arctic; Sea

ABSTRACTSchulsonOPP-0328605HiblerOPP-0328728The Principal Investigators describe new numerical and laboratory experiments that should elucidates the physical mechanisms that underlie the formation and subsequent behavior of failure zones that form within the annual arctic sea ice cover. The failure zones, termed. linear kinematic features (LKFs), often occur in conjugate sets of sub-parallel faults that traverse a large fraction of the arctic basin. Upon formation, the ice cover generally dilates somewhat and subsequently oscillates, thereby enhancing transfer of heat from the ocean to the atmosphere as well as increasing oceanic salt flux as new ice forms on open water. The LKF.s/faults most probably affect the ice thickness distribution in that, upon subsequent convergence of the ice pack, pressure ridging occurs. The lineaments (and other large-scale fracture features) are similar in appearance to smaller-scale compressive shear faults seen in laboratory specimens, suggesting, when the fractal character of ice breakup is also taken into account, that the physics of fracture is scale independent. Three different sets of numerical experiments will be performed. In the first series, idealized and numerical grid experiments will be carried out to examine the effect of different flow rules on fault formation and on the attendant weakening of the pack. In the second set, idealized spatially-varying wind forcing will be used with heterogeneous initial strength and a laboratory-generated flow rule to investigate the characteristic opening and closing of deformation faults as well as their angle of intersection. In the third series, high-resolution basin-wide modeling will be performed using a full-thickness ice distribution formulation. These simulations will be compared with a variety of recently acquired deformation data, most notably with recently declassified thickness-distribution data from upward-looking submarine sonar observations. Such comparisons will access the utility and applicability of this research to numerical air-ice-ocean models for the numerical investigation of climate. Five sets of systematic biaxial compressive experiments will be performed in the laboratory on blocks of salt-water ice.Intellectual Merit: In focusing on the development of a scale-independent sea-ice model, particularly applicable to spatial resolutions less than 10 kilometers and to the resolution of failure zones/faults, this research represents a new paradigm for sea ice dynamics. Under this paradigm, high internal ice stresses leading to localized fracture occur over short periods of time and rapidly decrease as a fault is formed. This differs significantly from conventional formulations (of the ice pack and its thickness distribution) which are used in current numerical investigations of climate and which implicitly assume a smoothly-varying deformation field in both time and space. The expectation is that the new model will more realistically capture the distribution in sea ice thickness and, thus, will be more useful in the numerical modeling of climate and its sensitivity to the polar sea ice cover. Broader Impacts: The research will constitute an intense intellectual enquiry carried out with the assistance of graduate students at two universities active in polar research. It will contribute to the intellectual development of a new generation of investigators, as well as enhance the research environment of the two institutions. In addition, through the revelation and understanding of new physical effects, the study will enrich both the undergraduate and graduate teaching of the Principal Investigators. The activity will contribute also to a working partnership in polar studies between Dartmouth and The University of Alaska. To enhance scientific and technical understanding, the results of the work will be disseminated broadly, through presentations to workshops and societal meetings and through contributions to the technical and scientific literature. A review article or book chapter is also planned.

主要研究人员描述了新的数值和实验室实验，这些实验应该阐明在每年的北极海冰覆盖范围内形成的破坏区的形成和随后的行为的物理机制。失败的区域，被称为。线性运动学特征（LKF）经常出现在穿过北极盆地的大部分的近平行断层的共轭集合中。在形成时，冰盖通常会有些膨胀，随后会振荡，从而加强了从海洋到大气的热量传递，并随着新冰在开放水域上形成而增加了海洋盐通量。的LKF.s/故障最有可能影响冰的厚度分布，在随后的收敛的冰袋，压力脊发生。 线性构造（和其他大规模的断裂特征）在外观上类似于实验室标本中看到的较小规模的压缩剪切断层，这表明，当冰破裂的分形特征也被考虑在内时，断裂的物理性质是与尺度无关的。 将进行三组不同的数值实验。 在第一个系列中，将进行理想化和数值网格实验，以检查不同的流动规则对断层形成和对伴随的包弱化的影响。在第二组中，理想化的空间变化的风强迫将被用于异构的初始强度和实验室产生的流动规则，以调查的特征打开和关闭的变形故障，以及它们的交叉角。在第三个系列中，将使用全厚度冰分布公式进行高分辨率全流域建模。这些模拟将与最近获得的各种变形数据进行比较，最值得注意的是最近解密的厚度分布数据，从向上看潜艇声纳观测。这样的比较将访问本研究的效用和适用性的数值空气-冰-海洋模式的气候数值调查。五套系统的双轴压缩实验将在实验室中进行的块盐水ic.Intellectual优点：在专注于开发一个独立的海冰模型，特别适用于空间分辨率小于10公里和故障区/故障的分辨率，这项研究代表了海冰动力学的新范式。 在这种模式下，导致局部断裂的高内部冰应力在短时间内发生，并随着断层的形成而迅速减小。 这显着不同于传统的配方（的冰袋和它的厚度分布），这是在目前的气候数值研究中使用的，并隐含地假设一个平滑变化的变形场在时间和空间。预计新模型将更真实地捕捉海冰厚度的分布，从而在气候数值模拟及其对极地海冰覆盖的敏感性方面更有用。更广泛的影响：这项研究将是在两所积极从事极地研究的大学的研究生的协助下进行的一项激烈的智力调查。它将有助于新一代调查人员的智力发展，并改善两个机构的研究环境。此外，通过揭示和理解新的物理效应，本研究将丰富本科和研究生教学的主要研究者。该活动还将有助于达特茅斯和阿拉斯加大学之间在极地研究方面的工作伙伴关系。为了加强对科学和技术的了解，将通过在讲习班和社会会议上的介绍以及通过对技术和科学文献的贡献，广泛传播这项工作的成果。 还计划撰写一篇评论文章或书籍章节。