Unravelling the Role of Subglacial Channels in Ice Stream Evolution

该项目是与新西兰科学家进行的国际合作的一部分，将对南极洲一个活跃的冰下水道进行实地勘探。 它将通过南极洲西部卡姆冰流中的一个钻孔部署Icefin机器人，以提供关于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。 大约160年前，坎布冰流从活跃转变为停滞。 通过Icefin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，以更好地了解冰下渠道如何调解上游接地冰川的冰和水文之间的交换，以及下游漂浮部分下的冰架和冰架下海洋环流。该团队的目标是获得冰流动态的新视角，以约束在变暖的世界中未来行为的预测。独特的水下航行器Icefin将与新西兰南极洲合作部署，新西兰南极洲正在坎布冰流的地面区域通道建立营地。Icefin携带机载传感器，可以绘制冰、海底和水柱的物理结构。Icefin观测将测试两个关键假设：冰流水文的转变导致通道中记录的停滞，以及通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，海洋学系泊和地球物理调查，这些数据应该能够更好地了解冰下流出物和海洋之间的联系，以及这些相互作用如何随着时间的推移而演变。将沿着钻孔上游和下游约3-4公里的部分绘制高分辨率冰下水道图。收集到的数据将被分析，以产生冰，海洋和海底的重建，然后建模和数据解释将建立一个多参数的三维上下文的通道。这个奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

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.