Satellite Observations and Modelling of Surface Meltwater Flow and its Impact on Ice Shelves

冰架减缓了为它们提供食物的地面冰盖的移动。这降低了冰盖向海洋流失质量并导致海平面上升的速度。但是冰架很容易坍塌，特别是当表面融水在脆弱地区积聚时。融水湖可以在冰架内制造和扩大裂缝，从而引发或加速冰架崩塌。此外，冰架内的水重新冻结会使冰变暖，并可能通过改变冰的粘度来影响冰的流动，而粘度取决于温度。南极洲表面的排水及其积聚的地方很少受到关注。这种排水被认为是微不足道的，但最近的研究表明，融水可以在冰架表面排放数十公里，并进入否则不会积累融水的地区。地表融水的排水可能在未来冰盖的稳定性中发挥重要作用。这个排水系统是这个项目的重点。该团队将开发和测试基于物理的水流和冰架流动的数学模型，密切关注遥感观测，以询问(1)排水系统将如何响应本世纪预计的融化速度的增加，(2)排水系统如何受到冰动力学的影响，(3)扩大的排水系统是否可以将融水输送到易受水驱动崩塌影响的冰架区域。研究小组假设，雪和雪中的融水重新冻结将通过影响雪/雪的渗透性来证明对水文学的重要性，并通过释放冰内的潜热和降低冰的粘度来证明冰架动力学。该项目将通过(1)对南极洲周围融水系统的结构和时间演变进行遥感调查，(2)开发和分析跨冰架水流的数学模型，以及(3)检验冰架水流的理想和现实模型来研究这些问题。该项目将首次资助一名NSF PI，一名博士后研究员和一名研究生。一项外展活动将利用新兴的增强现实技术，以三维方式可视化冰盖的动态，从而在纽约市周围的外展活动中激发公众对冰川学的兴趣。随着增强现实技术的不断普及，这种方法将被公开，以供更广泛的使用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Ice shelves slow the movement of the grounded ice sheets that feed them. This reduces the rate at which ice sheets lose mass to the oceans and contribute to sea-level rise. But ice shelves can be susceptible to collapse, particularly when surface meltwater accumulates in vulnerable areas. Meltwater lakes can create and enlarge fractures within the ice shelves, thereby triggering or hastening ice-shelf collapse. Also, water refreezing within ice shelves warms the ice and could affect the flow of the ice by changing its viscosity, which depends on temperature. The drainage of water across the surface of Antarctica and where it accumulates has received little attention. This drainage was assumed to be insignificant, but recent work shows that meltwater can drain for tens of kilometers across ice-shelf surfaces and access areas that would otherwise not accumulate meltwater. Surface meltwater drainage could play a major role in the future stability of ice sheets. This drainage is the focus of this project. The team will develop and test physics-based mathematical models of water flow and ice-shelf flow, closely informed by remote sensing observations, to ask (1) how drainage systems will grow in response to the increased melt rates that are predicted for this century, (2) how this drainage is influenced by ice dynamics and (3) whether enlarged drainage systems could deliver meltwater to areas of ice shelves that are vulnerable to water-driven collapse. The team hypothesizes that refreezing of meltwater in snow and firn will prove important for hydrology by impacting the permeability of the snow/firn and for ice-shelf dynamics by releasing latent heat within the ice and lowering ice viscosity. The project will examine these issues by (1) conducting a remote sensing survey of the structure and temporal evolution of meltwater systems around Antarctica, (2) developing and analyzing mathematical models of water flow across ice shelves, and (3) examining idealized and realistic models of ice-shelf flow. This project will support a first-time NSF PI, a post-doctoral researcher and a graduate student. An outreach activity will make use of the emerging technology of Augmented Reality to visualize the dynamics of ice sheets in three dimensions to excite the public about glaciology at outreach events around New York City. This approach will be made publicly available for wider use as Augmented Reality continues to grow in popularity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.