Collaborative Research: Building Geologically Informed Bed Classes to Improve Projections of Ice Sheet Change

预测南极冰盖的未来变化对于了解未来几个世纪全球海平面的变化至关重要。 这些预测依赖于冰盖流动模型，而冰盖流动模型又依赖于对冰下南极大陆物理条件的了解。 对南极洲的陆地、海上和空中探索加深了我们对南极冰盖下地质物质的了解，但这些信息尚未完全融入冰盖模型中。 该项目将利用数十年美国和国际地球物理调查投资的现有数据，对阿蒙森海和西南极冰盖邻近地区的地质有新的认识——南极洲的一部分被认为特别容易崩塌。 将开发一系列称为“床类”的新数据集，以可纳入冰盖模型的方式转化南极大陆的地质特性。 该项目将利用广泛的海洋和航空地球物理数据以及地面陆上地球物理和地质约束，为阿蒙森海湾及其冰集水区开发一个新的区域地质/构造框架，以描绘沉积盆地、基岩山脊、断层和火山结构。利用该地区的这种新的地质解释，将解决有关地质对冰盖稳定性影响的几个关键问题：区域热流是否由沿断层或岩性的局部化主导；地质对冰下水的源头、汇和流动路径的作用；决定河床特征变异性的沉积物分布；以及当前思韦茨冰川接地线的地质控制范围。改进的地质知识对冰盖模型的影响将通过开发一组“床类”网格来测试，以捕获这些新的见解以用于模型。 床类将在平行冰盖模型框架内进行测试，并通过初步实验来确定模型模拟对地质参数化的敏感性。 通过与冰盖建模师举办的一系列研讨会，床类将得到完善，并可供更广泛的建模界使用。 这项工作旨在确保 Bed-Class 概念能够更广泛地应用于不同地理区域和不同时间尺度的冰盖模型。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Predictions of future changes of the Antarctic ice sheet are essential for understanding changes in the global sea level expected for the coming centuries. These predictions rely on models of ice-sheet flow that in turn rely on knowledge of the physical conditions of the Antarctic continent beneath the ice. Exploration of Antarctica by land, sea, and air has advanced our understanding of the geological material under the Antarctic ice sheet, but this information has not yet been fully integrated into ice-sheet models. This project will take advantage of existing data from decades of US and international investment in geophysical surveys to create a new understanding of the geology underlying the Amundsen Sea and the adjacent areas of the West Antarctic Ice Sheet—a portion of Antarctica that is considered particularly vulnerable to collapse. A series of new datasets called “Bed Classes” will be developed that will translate the geological properties of the Antarctic continent in ways that can be incorporated into ice-sheet models. This project will develop a new regional geologic/tectonic framework for the Amundsen Sea Embayment and its ice catchments using extensive marine and airborne geophysical data together with ground-based onshore geophysical and geological constraints to delineate sedimentary basins, bedrock ridges, faults, and volcanic structures. Using this new geologic interpretation of the region, several key issues regarding the geologic influence on ice-sheet stability will be addressed: whether the regional heat flow is dominated by localization along the faults or lithology; the role of geology on the sources, sinks, and flow-paths of subglacial water; the distribution of sediments that determine bed-character variability; and the extent of geologic control on the current Thwaites Glacier grounding line. The impact of improved geological knowledge on ice-sheet models will be tested with the development of a set of “Bed Class” grids to capture these new insights for use in the models. Bed Classes will be tested within the Parallel Ice Sheet Model framework with initial experiments to identify the sensitivity of model simulations to geological parameterizations. Through a series of workshops with ice-sheet modelers, the Bed Classes will be refined and made accessible to the broader modelling community. This work aims to ensure that the Bed-Class concept can be applied more broadly to ice-sheet models working in different geographic areas and on different timescales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.