Theory and Models of Ice Sheet Surface Melting Instabilities in the Past and Future

人们认为，在合并的冰盖交界处突然加速融化，导致了历史上一些最迅速的海平面上升事件。现有的冰盖表面融化理论不考虑这些地区，不能再现这些突然加速冰盖表面融化。为了预测未来海平面快速上升事件的可能性，重要的是要了解过去为什么会发生这样的事件。该项目将为冰鞍区域内冰盖表面融化不稳定性发展一种新的数学理论。它将把这一理论的预测与复杂的冰盖模型进行比较，并进行更逼真的模拟，以确定格陵兰冰盖是否可能在未来变暖的情况下突然加速融化。该项目包括一些更广泛的影响。海平面上升威胁着全世界沿着的生命和基础设施。准确预测未来海平面可能快速上升的时期，将为有关减缓战略和基础设施设计的战略决策提供信息。该项目还将通过支持一名博士后助理和一名研究生的培训，为STEM劳动力的发展做出贡献。将制作一个采用该项目期间开发的简单模型的网络应用程序，作为向公众解释冰盖动态的有效推广工具。该项目的主要目标是开发一种理论，解释气候变暖条件下陆基冰盖发生的冰川融水脉冲。一个新的变种的经典单圆顶冰盖模型，放松以前的假设，并认为冰鞍几何将产生。这个新的冰鞍模型将进行数值测试，以确定在何种条件下，它产生了显着的冰消融水脉冲。渐近数学技术，如多时间尺度分析，将被用来推导这些模型预测的融水脉冲的幅度和速度的函数表达式。冰鞍理论在解释现实中的效用将通过与更复杂的冰盖模型和融水脉冲期间海平面上升的代理记录进行比较来评估。最后，将在未来气候变化的不同假设情况下，对格陵兰冰盖进行多千年模拟。

Sudden accelerations in melting at the junction of merged ice sheets are thought to have caused some of the most rapid sea level rise events in history. Existing theories of ice sheet surface melting do not consider such regions and are not able to reproduce these sudden accelerations in ice sheet surface melting. To predict the likelihood of such rapid sea level rise events in the future, it is important to understand why such events happened in the past. This project will develop a new mathematical theory for ice sheet surface melting instabilities within ice saddle regions. It will compare the predictions of this theory to complex ice sheet models and perform more realistic simulations to determine whether the Greenland Ice Sheet may undergo such a sudden acceleration in melting under future warming. This project includes a number of broader impacts. Sea level rise threatens life and infrastructure along coastlines throughout the world. Accurate projections of potential periods of rapid future sea level rise will inform strategic decision-making about mitigation strategies and infrastructure design. The project will also contribute to STEM workforce development by supporting the training of a post-doctoral associate and a graduate student. A web-based application employing the simple model developed during this project will be produced as an effective outreach tool for explaining ice sheet dynamics to the public.The primary goal of this project is to develop a theory that explains the occurrence of deglacial meltwater pulses from land-based ice sheets under a warming climate. A new variant on the classical single-dome ice sheet model that relaxes previous assumptions and considers an ice-saddle geometry will be produced. This new ice-saddle model will be numerically tested to determine the conditions under which it produces a significant deglacial meltwater pulse. Asymptotic mathematical techniques, such as multiple time scales analysis, will be used to derive functional expressions for the magnitude and speed of meltwater pulses predicted by these models. The utility of the ice-saddle theory in explaining reality will be evaluated by comparing it to more complex ice sheet models and proxy records of sea level rise during meltwater pulses. Finally, multi-millennial simulations of the Greenland Ice Sheet under different scenarios of future climate change will be developed.