Collaborative Research: Computational Methods Supporting Joint Seismic and Radar Inversion for Ice Fabric and Temperature in Streaming Flow

GERBI/1643301该奖项支持一个开发软件的项目，该软件将允许考虑进行地震或雷达实地勘测的研究人员提前测试他们计划收集的数据是否具有足够的分辨率来测量冰的机械特性的自然变化，这些变化决定了流动冰对不断变化的气候条件的反应。冰的力学性质在很大程度上取决于构成冰的晶体的温度和取向。测量冰晶取向和温度最准确的方法是通过钻探和直接分析冰芯。然而，这种方法非常昂贵、耗时，而且空间覆盖范围有限。地球物理技术，如地震和雷达，可以覆盖更多的领域，但我们对这些技术的实际限制知之甚少，因为它们与计算力学性能有关。该项目通过建立一个计算工具箱来解决这一知识鸿沟，该工具箱将能够准确评估地球物理测量成像晶体取向和冰温的能力。然后，研究人员可以使用这些工具来调整实地调查计划，以实现投资回报最大化。通过努力提高未来与冰川流动相关的地球物理工作的效率和效果，这项提议将改善科学家？在气候变化的更大背景下量化海平面变化的能力。该项目包括建立新的用户友好的、可公开访问的软件和教学模块。这项工作将为研究生和本科生提供培训，他们将在研究和开发教学材料方面发挥作用。冰的粘度，即冰的流动阻力，对冰的速度有很大的控制作用。因此，绘制冰层粘度图对于了解冰川和冰盖当前和未来的行为很重要。要做到这一点，科学家必须确定整个冰层的温度和晶体取向结构。地震和雷达技术可以快速探测大片区域，因此是有效测量流动冰的热结构和机械结构的有前途的方法，但尚未得到充分测试。作为该项目的一部分，科学家们将开发并使用一个计算框架来量化地震和雷达技术在多大程度上能够分辨流动的冰的晶体取向组构和温度，然后测试冰流对随之而来的不确定性的敏感度。为了实现这些目标，将建立一个数字工具箱，允许改变冰川/冰流的几何形状和物理性质(温度、晶体取向组构、密度和酸度)。该工具箱将能够通过正演模拟和反演合成剖面来创建合成雷达剖面和地震剖面，以评估地球物理技术成像原始热结构和机械结构的效果。这些模拟的雷达和地震数据将使科学家能够更好地量化冰的力学性质的可变性对流动速度和模式的影响。这项工作的结果将指导今后实地活动的规划，使其更有效力和效率。这个项目不需要在南极进行实地考察。

Gerbi/1643301This award supports a project to develop software that will allow researchers considering seismic or radar field surveys to test, ahead of time, whether the data they plan to collect will have sufficient resolution to measure the natural variations in the mechanical properties of ice, which determine the response of flowing ice to changing climatic conditions. The mechanical properties of ice depend largely on the temperature and the orientation of the crystals that make up the ice. The most accurate method for measuring ice crystal orientation and temperature is through drilling and direct analysis of an ice core. However, this method is very costly, time-consuming, and limited in spatial coverage. Geophysical techniques, such as seismic and radar, can cover much more area, but we have little knowledge about the practical limitations of these techniques as they relate to calculating mechanical properties. This project addresses that knowledge gap through construction of a computational toolbox that will allow accurate assessment of the ability of geophysical surveys to image crystal orientation and ice temperature. Researchers can then use these tools to adjust the field survey plans to maximize the return on investment. By working to improve the efficiency and effectiveness of future geophysical work related to glacial flow, this proposal will improve scientists? ability to quantify sea-level variations within the larger context of climate change. The project includes building new user-friendly, publicly accessible software and instructional modules. The work will provide training for graduate and undergraduate students, who will play a role in research and develop instructional materials. Ice viscosity, the resistance of ice to flow, exerts significant control over ice velocity. Therefore, mapping ice viscosity is important for understanding the current and future behavior of glaciers and ice sheets. To do so, scientists must determine the temperature and crystal orientation fabric throughout the ice. Seismic and radar techniques can survey large areas quickly, and thus are promising, yet not fully tested, methods to efficiently measure the thermal and mechanical structure of flowing ice. As part of this project, scientists will develop and use a computational framework to quantify the degree to which seismic and radar techniques can resolve the crystal orientation fabric and temperature of streaming ice, and then test how sensitive ice flow is to the attendant uncertainty. To meet these goals, a numerical toolbox will be built which will allow the glacier/ice stream geometry and physical properties (temperature, crystal orientation fabric, density and acidity) to be varied. The toolbox will be capable of both creating synthetic radar and seismic profiles through forward modeling and inverting synthetic profiles to allow evaluation of how well geophysical techniques can image the original thermal and mechanical structure. These simulated radar and seismic data will allow scientists to better quantify the influence of the variability in mechanical properties of the ice on flow velocities and patterns. The results of this work will guide planning for future field campaigns, making them more effective and efficient. This project does not require fieldwork in the Antarctic.