Collaborative Research: EAGER: A Dual-Band Radar for Measuring Internal Ice Deformation: a Multipass Ice-Penetrating Radar Experiment on Thwaites Glacier and the McMurdo Ice Shelf

该项目将开发一种新的破冰雷达系统，该系统可以同时绘制冰川几何形状和沿重复剖面的冰川流动。预测冰盖对海平面的贡献，需要对最初的冰盖几何形状和控制冰在基岩上流动和滑动的参数进行估计。现有的冰盖模式不能从传统的冰面速度和冰川几何形状观测中独立地确定这一信息。这给过去和未来冰盖行为的模拟带来了很大的不确定性。因此，这种新的雷达能力被设想为提供所需的数据，以支持对过去和未来冰盖行为的更高保真度的模拟，以及对未来海平面的更准确预测。新的雷达系统将集成由冰盖遥感中心开发的两种现有雷达（多通道相干无线电回波测深仪和积累雷达），并增加新的功能。一个八元甚高频（VHF; 140-215 MHz）阵列将具有足够的交叉轨道孔径，以三维方式绘制内层和冰盖基础。单个超高频（UHF; 600-900 MHz）天线将具有范围和相位分辨率，以0.25 mm精度映射内层位移。VHF阵列将创建层几何的3D映射，通过考虑重复剖面之间的空间偏移和变化的地面条件，可以测量垂直速度。垂直位移测量将通过确定在不同时间在同一地点收集的雷达剖面的超高频天线记录的雷达相位响应的差异来进行。超高频天线将是双极化的，因此能够隔离复杂内部反射的两个分量。这将有助于推断冰晶取向结构和冰粘度的广泛映射。该雷达的初步现场测试将在麦克默多冰架进行，然后进展到南极洲的思韦茨冰川。双频雷达系统技术和处理算法将与多功能可扩展硬件和用户友好软件一起开发，因此该系统将作为未来社区雷达系统的原型。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。

This project will develop a new ice-penetrating radar system that can simultaneously map glacier geometry and glacier flow along repeat profiles. Forecasting an ice-sheet’s contribution to sea level requires an estimate for the initial ice-sheet geometry and the parameters that govern ice flow and slip across bedrock. Existing ice-sheet models cannot independently determine this information from conventional observations of ice-surface velocities and glacier geometry. This introduces substantial uncertainty into simulations of past and future ice-sheet behavior. Thus, this new radar capability is conceived to provide the needed data to support higher-fidelity simulations of past and future ice-sheet behavior and more accurate projections of future sea level.The new radar system will integrate two existing radars (the multi-channel coherent radio-echo depth sounder and the accumulation radar) developed by the Center for the Remote Sensing of Ice Sheets, as well as adding new capabilities. An eight-element very high frequency (VHF; 140-215 MHz) array will have sufficient cross-track aperture to swath map internal layers and the ice-sheet base in three dimensions. A single ultra high frequency (UHF; 600-900 MHz) antenna will have the range and phase resolution to map internal layer displacement with 0.25-mm precision. The VHF array will create 3D mappings of layer geometry that enable measurements of vertical velocities by accounting for spatial offsets between repeat profiles and changing surface conditions. The vertical displacement measurement will then be made by determining the difference in radar phase response recorded by the UHF antenna for radar profiles collected at the same locations at different times. The UHF antenna will be dual-polarized and thus capable of isolating both components of complex internal reflections. This should enable inferences of ice crystal orientation fabric and widespread mapping of ice viscosity. Initial field testing of the radar will occur on the McMurdo Ice Shelf and then progress to Thwaites Glacier, Antarctica. The dual-band radar system technology and processing algorithms will be developed with versatile extensible hardware and user-friendly software so that this system will serve as a prototype for a future community radar system.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.