Collaborative Research: Stability and Dynamics of Antarctic Marine Outlet Glaciers

本研究的目的是更好地了解南极西部从接地冰到浮冰架过渡地区的冰流，并调查可以启动和维持这些冰川大规模退缩的条件。几个主要的南极出口冰川和冰流将使用一套观测技术和建模工具进行调查。冰川包括斯韦茨冰川（Thwaites Glacier），它已成为讨论南极西部退缩的焦点，惠兰斯冰流（Whillans Ice Stream）是冰流原型的一个例子，还有伯德冰川（Byrd Glacier），这是一个主要的出口冰川，流经南极横贯山脉，将东南极洲排入罗斯冰架。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。为了充分纳入出口冰川和冰流的动态行为，需要包括相关的物理过程，并开发区域模型，这些模型采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尺度的床地形特征。该奖项重新审视了海洋冰川的稳定性问题，这些冰川的接地线位于后退的床坡上。特别是，将试图解决观测到的快速变化是终端或接地线扰动的结果，还是这些变化反映了接地段的冰动力强迫。高分辨率卫星图像将用于在比以前更小的空间尺度上研究冰流扰动，以评估高基础阻力局部地点对地线稳定性的重要性。该合作项目涉及一系列建模策略，包括力预算分析、流带建模、用于局部研究的Full Stokes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线模型，使其包括更现实的接地线动态。

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.