OPP-PRF: High-resolution Nested Antarctic Ice Sheet Modeling to Reconcile Marine and Terrestrial Geologic Data

地质数据提供了对南极冰盖动力学的重要见解；例如，从冰盖中逐渐显露出来的山峰揭示了冰的高度变化，海洋冰盖过去的“足迹”被印在了海底。数值冰盖模拟可以将这些地质记录在空间和时间上联系起来，从而对整个大陆的冰盖演变做出更大规模的推断。这项工作将海洋和陆地地质数据集与数值模拟结合起来，研究南极冰盖的行为（以及对全球海平面的贡献），从大约2万年前到现在。具体而言，本研究解决了两个关于模拟和数据之间的关系以及它们在重建过去冰盖行为中的应用的问题：(1)现代海底的地质记录表明，与山峰暴露（冰变薄）的陆地记录相比，海洋冰的退缩明显更早。计算机实验研究了这种时间不匹配的几种假设。(2)暴露年龄数据（记录冰高程变化的陆地测量数据）通常被解释为反映数百公里外研究地点的冰动力学。这项工作使用模拟来探索冰川流经山区时“上游”的冰高程变化与冰接触海洋时“下游”的冰动态之间的联系。这项工作将产生一个公开可用的、可定制的、易于访问的工具包，用于比较模拟和数据，包括一个地质记录数据库，用作约束条件。该项目是跨学科的，弥合了冰盖模拟和地质数据收集社区之间的沟通差距。该项目结合数值模拟和地质数据，探索有关海洋和陆地数据集的解释和使用的基本知识空白。这项工作将产生一个全大陆范围的耦合冰盖和冰川均衡调整模拟的集合，在综合现有地质数据的约束下，再现与地质记录以及冰川学和重力自一致的南极冰盖去冰演化历史。通过高分辨率嵌套冰盖建模技术，改进了模拟和数据之间的比较，为通常位于复杂地形区域的暴露年龄数据提供了前所未有的背景。数值模拟将在系统变化的参数和边界条件下进行，从而可以支持以下研究：(1)全新世中期陆地变薄和海洋冰盖退缩之间的年代不匹配；(2)在各种不同情景下，海洋基准线动力学如何向上游传播到沿海出口冰川和进一步向内部传播。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Geologic data provide crucial insights into Antarctic Ice Sheet dynamics; for example, progressive exposure of mountain peaks emerging from the ice sheet reveal ice elevation changes, and the past ‘footprint’ of marine-based ice sheets is imprinted on the seafloor. Numerical ice sheet simulations can link these geologic records in space and time to make larger-scale inferences about continent-wide ice sheet evolution. This work integrates both marine and terrestrial geologic datasets with numerical simulations to investigate Antarctic Ice Sheet behavior (and contribution to global sea level) throughout the last deglaciation, ~20,000 years ago until present. Specifically, this research addresses two issues regarding the relationship between simulations and data and their use in reconstructing past ice-sheet behavior:(1) Geologic records from the modern seafloor suggest significantly earlier retreat of marine-based ice compared to terrestrial records of mountain peak exposure (ice thinning). Computer experiments investigate several hypotheses for this mismatch in timing.(2) Exposure age data (terrestrial measurements recording ice elevation changes) are often interpreted to reflect ice dynamics hundreds of kilometers away from the study site. This work uses simulations to explore the linkage between ice elevation changes ‘upstream’ as glaciers flow through mountainous regions and ice dynamics further ‘downstream’ where ice contacts the ocean.This work will produce a publicly available, customizable, and easily accessible toolkit for comparing simulations and data, including a database of geologic records to use as constraints. The project is interdisciplinary, bridging a communication gap between the ice-sheet simulations and geologic data-collecting communities.This project combines numerical simulations and geologic data to explore fundamental knowledge gaps regarding the interpretation and use of marine and terrestrial datasets. This work will produce an ensemble of continent-wide coupled ice sheet and glacial isostatic adjustment simulations, constrained with comprehensive existing geologic data, to reproduce a history of deglacial Antarctic Ice Sheet evolution that is compatible with the geologic record as well as glaciologically and gravitationally self-consistent. Comparison between simulations and data is improved through high-resolution nested ice sheet modeling techniques, which provide unprecedented context for exposure age data generally located in regions of complex topography. Numerical simulations will be performed with systematically varied parameters and boundary conditions, and can thus support an investigation of (1) chronological mismatches between terrestrial thinning and marine ice sheet retreat during the mid-Holocene, and (2) how marine grounding-line dynamics are propagated upstream to coastal outlet glaciers and further interior under a variety of different scenarios.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.