Numerical Simulations of Heinrich Events (Binge/Purge Oscillations of the Laurentide Ice Sheet)

9321457 MacAyeal这个奖项是为了支持一个项目，该项目对海因里希事件（大约每7000年发生一次的劳伦泰德冰原冰山崩解的短暂但剧烈的事件）的机制进行有限元建模研究。研究假设海因里希事件是由劳伦泰德冰盖流动的自由振荡引起的（“豪饮/清洗”振荡理论），这种振荡的产生是因为哈德逊湾和哈德逊海峡的底部覆盖着柔软的、未固结的沉积物，这些沉积物在融化时形成了光滑的润滑剂。建模工作将是新颖的，因为两个独立的有限元网格，每个网格都旨在优化不同冰流机制限制下的计算性能，将用于异步推进Laurentide冰盖的冰厚分布（和其他领域）。提出的研究结果将包括：1)通过将模型输出与地质记录进行比较，验证海因里希事件的暴/吹扫振荡理论；2)估计与各种基底碎片夹带方法相关的冰载碎片通量；3)确定海因里希事件前后的冰地形，用于大气环流模型。＊＊＊

9321457 MacAyeal This award is for support for a project to conduct a finite-element modeling study of the mechanism for Heinrich Events (brief, but violent episodes of iceberg disgorgement from the Laurentide Ice Sheet occuring approximately every 7000 years). The research assumes that Heinrich events were caused by free-oscillations in the flow of the Laurentide ice sheet ("binge/purge" oscillator theory) which arose because the floor of Hudson Bay and Hudson Strait is covered with soft, unconsolidated sediment that forms a slippery lubricant when thawed. The modeling work will be novel in the sense that two separate finite-element grids, each designed to optimize computational performance under the restrictions of diverse ice flow mechanisms, will be used to asynchronously advance the ice thickness distribution (and other fields) of the Laurentide ice sheet through time. The outcome of the proposed research will include: 1) a verification of the binge/purge oscillator theory of Heinrich Events through comparison of model output with the geologic record, 2) estimation of the ice-rafted debris flux associated with various methods of basal debris entrainment, and 3) determination of the pre- and post-Heinrich Event ice topographies for use in atmospheric circulation models. ***