Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers

1245871/ mccarthy该奖项支持一个项目，该项目使用一种新的定制的低温摩擦装置进行实验室实验，以探索冰川变形振荡应力，就像大自然中潮汐冰川所经历的那样。实验设计将探讨周期性加载冰在岩石上滑动的动力摩擦特性。虽然过去已经研究过冰的摩擦强度，但这些研究都集中在恒定的加载和滑动速率上。这项工作的结果将通过改善对关键材料和摩擦特性的限制，并允许基于物理的预测由于潮汐引起的应力变化的冰川应变的幅度和相位，从而促进对冰流动力学的理解。这项工作的智力价值在于，它将导致对动态流变参数的更好理解，并将为动态冰川流动提供更好的预测工具。提出的实验将提供南极冰川在实际频率下冰和岩石变形的动态材料特性。pi将测量从弹性到非弹性到粘性的材料响应的全谱。该研究将为提高冰川和冰流对外界强迫响应的预测能力提供更好的约束条件。这项工作更广泛的影响包括提供对材料特性的估计，这可以用来扩大我们对冰川流动的理解，并最终用于海平面上升和冰盖稳定性的模型。预测近期海平面的能力取决于对南极冰流和冰川流动过程的了解。海洋潮汐对冰川流动的调节代表了一种自然实验，可以用来提高对冰和床性质的认识，以及这些性质依赖于时变强迫的方式。目前，人们对潮汐强迫对冰川运动的影响了解甚少，对潮汐载荷条件下冰的性质认识有限。这项研究将通过研究地震学、冰川学和一般材料科学感兴趣的现象，产生超越极地科学的有趣结果。该项目将为两名本科生实习生提供宝贵的研究和实验室经验，并将为PI（目前为博士后）领导科学项目提供经验。这三位pi都是职业生涯早期的科学家。这项建议不需要在南极进行实地考察。

1245871/McCarthyThis award supports a project to conduct laboratory experiments with a new, custom-fabricated cryo-friction apparatus to explore ice deformation oscillatory stresses like those experienced by tidewater glaciers in nature. The experimental design will explore the dynamic frictional properties of periodically loaded ice sliding on rock. Although the frictional strength of ice has been studied in the past these studies have all focused on constant rates of loading and sliding. The results of this work will advance understanding of ice stream dynamics by improving constraints on key material and frictional properties and allowing physics-based predictions of the amplitude and phase of glacier strain due to tidally induced stress variations. The intellectual merit of this work is that it will result in a better understanding of dynamic rheological parameters and will provide better predictive tools for dynamic glacier flow. The proposed experiments will provide dynamic material properties of ice and rock deformation at realistic frequencies experienced by Antarctic glaciers. The PIs will measure the full spectrum of material response from elastic to anelastic to viscous. The study will provide better constraints to improve predictive capability for glacier and ice-stream response to external forcing. The broader impacts of the work include providing estimates of material properties that can be used to broaden our understanding of glacier flow and that will ultimately be used for models of sea level rise and ice sheet stability. The ability to predict sea level in the near future is contingent on understanding of the processes responsible for flow of Antarctic ice streams and glaciers. Modulation of glacier flow by ocean tides represents a natural experiment that can be used to improve knowledge of ice and bed properties, and of the way in which these properties depend on time-varying forcings. Presently, the influence of tidal forcing on glacier movement is poorly understood, and knowledge of ice properties under tidal loading conditions is limited. The study will generate results of interest beyond polar science by examining phenomena that are of interest to seismology, glaciology and general materials science. The project will provide valuable research and laboratory experience for two undergraduate interns and will provide experience for the PI (currently a postdoc) in leading a scientific project. The three PIs are early career scientists. This proposal does not require fieldwork in the Antarctic.