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

主要研究人员描述了新的数值和实验室实验，这些实验应该能够阐明在每年北极海冰覆盖范围内形成的破坏带的形成和后续行为的物理机制。故障区，称为。线性运动特征（LKFs），通常发生在穿越北极盆地大部分地区的亚平行断层的共轭组中。在形成时，冰盖通常会有所膨胀并随之振荡，从而加强了从海洋到大气的热量传递，并随着新冰在开阔水域上形成而增加了海盐通量。兰桂坊。S /断层最有可能影响冰厚分布，因为在随后的冰团汇聚后，会发生压力脊。这些裂缝的轮廓（以及其他大规模裂缝特征）在外观上与实验室样品中看到的较小规模的压缩剪切断层相似，这表明，当考虑到冰破裂的分形特征时，裂缝的物理性质与尺度无关。将进行三组不同的数值实验。在第一个系列中，将进行理想网格和数值网格实验，以检验不同的流动规则对断层形成和伴随的包体弱化的影响。在第二组中，将使用具有非均匀初始强度和实验室生成的流动规则的理想空间变化风强迫来研究变形断层的开合特征及其相交角。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从向上看的潜艇声纳观测中解密的厚度分布数据。这样的比较将使这项研究对用于气候数值研究的空气-冰-海洋数值模式具有实用性和适用性。五组系统的双轴压缩实验将在实验室进行的块盐水冰。智力优势：本研究的重点是建立一个尺度无关的海冰模型，特别是适用于小于10公里的空间分辨率和失效带/断层的分辨率，代表了海冰动力学的新范式。在这种模式下，高内部冰应力导致局部断裂在短时间内发生，并随着断层的形成而迅速减小。这与目前气候数值研究中使用的常规公式（关于冰盖及其厚度分布）有很大的不同，后者隐含地假设在时间和空间上都有一个平滑变化的变形场。人们期望新模式能更真实地捕捉海冰厚度的分布，从而在气候及其对极地海冰覆盖的敏感性的数值模拟中更有用。更广泛的影响：这项研究将构成一个密集的知识探索，在两所大学的研究生的协助下进行极地研究。这有助培养新一代的研究人员，并改善两所院校的研究环境。此外，通过对新的物理效应的揭示和认识，本研究将丰富首席研究员的本科和研究生教学。该活动还将有助于达特茅斯学院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对技术和科学文献的贡献，广泛传播这项工作的结果。还计划写一篇评论文章或书籍章节。

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.