Collaborative Research: Stability and Dynamics of Antarctic Marine Outlet Glaciers

这项研究的目的是为了更好地了解南极西部从陆冰到浮冰过渡区域的冰流，并调查引发和维持这些冰川重大后退的条件。将使用一套观测技术和建模工具对几个主要的南极出口冰川和冰流进行调查。冰川包括Thwaites冰川，它已成为讨论南极西部退缩的焦点；Whillans Ice Stream，作为原型冰流的例子；以及Byrd Glacier，一个主要的出口冰川，将南极洲东部通过横贯南极的山脉排入罗斯冰架。这项研究将调查这些冰川的持续变化是否会导致长期的质量损失(冰盖崩塌的开始)，或者这些冰川是否会以新的几何形状迅速稳定下来。要充分纳入出口冰川和冰流的动态行为，需要纳入相关的物理过程，并开发区域模型，该模型使用具有足够精细的水平网格间距的数值网格，以捕捉可能控制这些冰川流动的较小规模的河床地形特征。该奖项重新讨论了海洋冰川的稳定性问题，这些冰川的接地线位于退缩的河床斜坡上。特别是，将试图解决所观察到的快速变化是否是终端或接地线扰动的结果，或者这些变化是否反映了接地段上的冰动力强迫。将使用高分辨率卫星图像在比以前更小的空间尺度上调查冰流扰动，以评估高基阻的局部位置对接地线稳定性的重要性。这一合作项目涉及一系列建模策略，包括力量预算分析、流带建模、用于本地研究的全斯托克斯建模，以及使用喷气推进实验室开发的冰盖系统模型进行区域建模。更广泛的影响包括培训两名研究生学习计算机模拟和冰盖建模算法。这项工作还将扩展基于网络的交互式流水线模型，以便它包括更真实的接地线动力学。

Van der Veen/1543530The objective of this research is to gain better understanding of the West Antarctic ice flow in the transition region from grounded ice to floating ice shelves and investigate the conditions that can initiate and sustain major retreat of these glaciers. Several major Antarctic outlet glaciers and ice streams will be investigated using a suite of observational techniques and modeling tools. Glaciers include Thwaites Glacier, which has become a focal point in the discussion of West Antarctic retreat, Whillans Ice Stream as an example of the archetype ice stream, and Byrd Glacier, a major outlet glacier draining East Antarctica through the Transantarctic Mountains into the Ross Ice Shelf. This study will investigate whether the ongoing changes in these glaciers will lead to long-term mass loss (the onset of ice sheet collapse), or whether these glaciers will quickly stabilize with a new geometry.To adequately incorporate the dynamic behavior of outlet glaciers and ice streams requires inclusion of the relevant physical processes, and the development of regional models that employ a numerical grid with a horizontal grid spacing sufficiently refined to capture smaller-scale bed topographic features that may control the flow of these glaciers. This award revisits the issue of stability of marine-terminating glaciers whose grounding line is located on a retrograded bed slope. In particular, an attempt will be made to resolve the question whether observed rapid changes are the result of perturbations at the terminus or grounding line, or whether these changes reflect ice-dynamical forcing over the grounded reaches. High-resolution satellite imagery will be used to investigate ice-flow perturbations on smaller spatial scales than has been done before, to evaluate the importance of localized sites of high basal resistance on grounding-line stability. This collaborative project involves a range of modeling strategies including force-budget analysis, flow-band modeling, Full Stokes modeling for local studies, and using the Ice Sheet System Model developed at JPL for regional modeling. Broader Impacts include training two graduate students in computer simulations and ice sheet modeling algorithms. The work will also expand on a web-based interactive flowline model, so that it includes more realistic grounding line dynamics.