Unravelling the Role of Subglacial Channels in Ice Stream Evolution

该项目是与新西兰科学家的国际合作的一部分，将对南极洲一条活跃的冰下水道进行现场勘探。它将通过西南极坎布冰流的一个钻孔部署冰鳍机器人车辆，以提供有关冰流底部发生的过程的新的三维背景，冰流在那里与海洋相遇并漂浮。坎布冰流大约在160年前从活跃转变为停滞。利用冰鳍金枪鱼提供的新视角，国际合作旨在整合遥感、地球物理和海洋学数据，以提高对冰下渠道如何调节上游搁浅冰川的冰和水文与下游漂浮部分下的冰架和冰架下海洋循环之间的交换的理解。该团队旨在获得有关冰流动态的新视角，以限制对未来全球变暖行为的预测。独一无二的水下机器人Icefin将与南极洲新西兰合作部署，后者正在坎布冰流的接地带航道上建立营地。冰鳍携带的传感器可以绘制冰层、海底和水柱的物理结构图。冰鳍观测将检验两个关键假设：冰流水文学的转变导致航道中记录的停滞，以及航道演变是由冰下水与海水流入相互作用引起的冰-海洋相互作用驱动的。结合新西兰同事进行的沉积物岩心、海洋系泊和地球物理调查，这些数据应该能够更好地了解冰下外流和海洋之间的联系，以及这些相互作用如何随着航道的增长而随着时间的推移而演变。将沿着钻孔上下约3-4公里的路段以高分辨率绘制冰下航道图。收集的数据将被分析以产生冰、海洋和海底的重建，然后建模和数据解释将为航道建立一个多参数的三维背景。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project, part of an international collaboration with scientists from New Zealand, will conduct in situ exploration of an active subglacial channel in Antarctica. It will deploy the Icefin robotic vehicle through a borehole in the Kamb Ice Stream in West Antarctica to provide new three-dimensional context on the processes occurring at the base of the ice stream where it meets the ocean and goes afloat. Kamb Ice Stream transitioned from active to stagnant roughly 160 years ago. With the new perspectives offered by Icefin, the international collaboration aims to integrate remote sensing, geophysical, and oceanographic data to improve understanding of how subglacial channels mediate the exchange between the ice and hydrology of the grounded glacier upstream with the ice-shelf and sub-ice-shelf ocean circulation under the downstream floating section. The team aims to gain new perspectives on the dynamics of ice streams to constrain projections of future behavior in a warming world.The uniquely capable underwater vehicle Icefin will be deployed in collaboration with Antarctica New Zealand who are establishing a camp at the grounding-zone channel at Kamb Ice Stream. Icefin carries onboard sensors that map the physical structure of the ice, seafloor, and water column. Icefin observations will test two key hypotheses: that transitions in the hydrology of the ice stream caused stagnation that is recorded in the channel, and that channel evolution is driven by ice-ocean interactions caused by subglacial water interacting with the inflow of ocean water. In combination with sediment cores, oceanographic moorings, and geophysical surveys conducted by New Zealand colleagues, these data should enable a better understanding of connections between subglacial outflow and the ocean, and how these interactions have evolved over time as the channel has grown. The subglacial channel will be mapped in high resolution along an approximately 3-4 km section up and downstream of the borehole. The collected data will be analyzed to produce reconstructions of the ice, ocean, and seafloor, and then modeling and data interpretation will build a multi-parameter three-dimensional context for the channel.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.