Modeling the Dynamics of Surface-slope Reversals and their Role in the Formation and Stability of Subglacial Lakes

该奖项支持了一项为期三年的建模工作，旨在了解冰流和冰架上冰-空气表面斜坡反转的动力学，这对冰下湖泊的形成和稳定具有重要意义。冰-气表面坡度的局部逆转可能通过水力梯度的逆转导致基底水和地表水的捕获，分别产生冰下湖和冰上湖。在冰下湖泊的情况下，一旦形成如此大的压力水水库，就有可能以大爆发洪水的形式或以较小但持续的冰下水流增加的时期的形式进行排水。这项研究试图扩展一些已经完成的初步工作，包括时间依赖性和更广泛的参数和几何形状。这些方法将涉及使用一套模型，所有这些模型都将包括纵向偏差和基底剪切应力，其中一些还将考虑横向阻力和内部垂直剪切。拟议活动的智力价值包括提高对冰流/冰架系统中地表斜坡反转形成过程和参数的理解，以及对由于斜坡反转而形成的冰下湖泊的稳定性的洞察。这项活动产生的更广泛的影响包括提供研究冰流/冰架系统动力学的工具，提高对爆发洪水背后的物理学的理解，以及对冰流与其冰下水系统耦合的见解。这项研究将支持一个刚起步的博士后研究员的研究。这项研究的结果将被纳入课程和公共宣传中，每年为数百到数千人服务。

This award supports a three-year modeling effort to understand the dynamics surrounding ice-air surface slope reversals on ice streams and ice shelves, with implications for the creation and stability of subglacial lakes. Local reversal of the ice-air surface slope may lead, through a reversal of the hydraulic gradient, to the trapping of basal and surface water, producing subglacial and supraglacial lakes, respectively. In the case of subglacial lakes, once such a sizable reservoir of pressurized water is created the potential exists for drainage, in the form of large outburst floods or as smaller, but sustained, periods of increased subglacial water flow. The research seeks to extend some initial work that has been done to include time-dependence and a wider array of parameters and geometries. The methods will involve the use of a suite of models, all of which will include longitudinal deviatoric and basal-shear stresses, with some also taking account of lateral drag and internal vertical shear. The intellectual merit of the proposed activity includes an improved understanding of the processes and parameters involved in the formation of surface-slope reversals in ice-stream/ice-shelf systems, as well as insight into the stability of subglacial lakes formed as a consequence of slope reversals. The broader impacts resulting from this activity include the provision of tools to study the dynamics of ice-stream/ice-shelf systems, an improved understanding of the physics behind outburst floods, and insights into the coupling of ice streams with their subglacial water systems. The research will support the studies of a beginning postdoctoral researcher. Results of the research will be incorporated into courses and public outreach serving anywhere from hundreds to thousands of people per year.