Ice-Shelf Rift Propagation: Computational Simulation Using a Fracture Fracture Mechanics Approach

该合同支持一个项目，该项目将基于线性弹性断裂力学（LEFM），结合现有的冰架蠕动-流动模型和新的裂缝模型，开发模拟冰架裂缝扩展的计算模型。拟议工作的总体目标是模拟裂谷扩展和最终的大型冰山崩解，并将这些过程置于更大的冰盖和气候背景下。这项工作将分阶段进行，首先开发单裂缝和多裂缝传播模型；然后利用这些模型对不同环境条件下的传播敏感性进行评价；第三，发展结合冰架系统内裂缝传播和平流的模式。模式的发展将根据对南极冰架若干特征地点裂谷传播的卫星观测进行指导和评价。新的冰断裂数值模型将应用于冰川学的许多问题。这里提出的研究是针对冰架的大裂谷形成和随后的冰山崩解。它的动机是需要了解观测到的现代冰架的变化，以及它们与气候的联系。在取样的地方，威德尔海区域的沉积记录暗示了半岛冰架在千年时间尺度上的变化。以可信的方式模拟冰山崩解的能力将提高我们重现此类事件的能力，并将冰架前进和后退的完整周期置于冰动力学背景下。反过来，这将使我们能够将冰架周期置于最终驱动冰盖质量平衡的气候周期中。

This award supports a project to develop computational models to simulate ice-shelf rift propagation using a combination of well-established ice-shelf creep-flow models and new crevasse models, based on linear elastic fracture mechanics (LEFM). The overall objective of the proposed work is to simulate rift propagation and eventual large iceberg calving,and place those processes within a larger ice sheet and climate context. The work will proceed in stages, first developing models of single-and multiple-crevasse propagation; then using those models to evaluate propagation sensitivity to various environmental conditions; and third developing models that incorporate both crevasse propagation and advection within an ice- shelf system. Model development will be guided by and evaluated according to satellite observations of rift propagation in several characteristic locations on Antarctic ice shelves. New numerical models of fracture in ice will have applications to many problems in glaciology. The research proposed here is directed toward large rift formation in ice shelves and subsequent iceberg calving. It is motivated by the need to understand observed changes in modern ice shelves,and their connection to climate. Where it has been sampled, the sedimentary record of the Weddell Sea sector implies Peninsular ice shelf variability on millennial time scales. The ability to simulate iceberg calving in a credible way will improve our ability to reproduce such events and place the complete cycle of ice shelf advance and retreat in an ice-dynamics context. That will, in turn, enable us to place ice-shelf cycles within the climate cycles that ultimately drive ice-sheet mass balance.