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

该奖项支持为期三年的建模工作，以了解冰流和冰架上冰-气表面坡度逆转的动态，并对冰下湖泊的形成和稳定性产生影响。当地扭转的冰-气表面坡度可能会导致，通过逆转的水力梯度，基底水和地表水的捕获，分别产生冰下和冰上湖泊。 在冰下湖泊的情况下，一旦形成这样一个相当大的压力水水库，就有可能以大洪水爆发或冰下水流增加的较小但持续的时期的形式排水。 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应力和基底剪应力，其中一些还考虑到横向阻力和内部垂直剪切。 拟议活动的智力价值包括更好地了解冰流/冰架系统中表面斜坡逆转形成的过程和参数，以及了解斜坡逆转形成的冰下湖泊的稳定性。 这一活动产生的更广泛影响包括：提供了研究冰流/冰架系统动态的工具，加深了对突发洪水背后的物理学的理解，以及深入了解冰流与冰下水系的耦合。这项研究将支持一个开始的博士后研究人员的研究。研究结果将纳入每年为数百至数千人提供服务的课程和公共宣传。

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.