Collaborative Research: A New Approach to Firn Evolution using the Taylor Dome Natural Laboratory

在冰川学中，雪花和冰川冰的转变是一个基本的过程。了解这一点对于许多应用至关重要，包括将卫星测高测量转换为冰盖质量变化--这是衡量冰川对气候变化反应的关键指标。更好的过程理解对于确定冰的年龄和困在冰中的气体的差异也是至关重要的。这种差异使冰芯的年龄测定变得复杂。尽管雪很重要，但人们对雪和冰的转化仍然知之甚少，目前的预测模型适用性有限。该项目旨在为冰川学社区开发一个基于物理的降雪压实模型。该团队将通过一系列现场和实验室实验以及模型开发，朝着这一目标迈出第一步。实地考察将在南极洲的泰勒穹顶进行。该项目将引入一种新的FIRN数据集组合，旨在开发下一代基于物理的FIRN模型。冰芯科学和卫星测高的进步要求降雪模型能够可靠地模拟在一系列气候条件下、在变化的气候中以及在长时间和短时间尺度上的降雪演变。目前的降雪压实模型主要基于稳态假设，并根据特定的地理位置进行调整。要超越这些模型，需要(1)测量当前的降雪压实速率，(2)测量在降雪压实中起关键作用的颗粒级微结构，以及(3)量化驱动这些微结构演变的过程。为了消除FIRN对堆积和温度的敏感性，研究小组将用两种独立的方法测量现场应变率，并在保持相同平均温度的情况下，观察泰勒穹顶堆积梯度上岩芯的微结构趋势。该团队将评估相敏雷达远程测量积雪压实率的能力，这可能会简化未来的现场测量。这项工作将为收集未来跨越温度累积空间关键区域的微观结构数据创建路线图，并通过开放源代码的社区Firn模型的可用性简化未来的合作。该奖项反映了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。

The transformation of snow into firn and then glacial ice is a fundamental process in glaciology. Understanding it is critical for many applications including the conversion of satellite altimetry measurements into ice-sheet mass changes—a key measure of glacier response to climate change. Better process understanding is also critical for determining the difference in the age of ice and the gas trapped within it. This difference complicates the age-dating of ice cores. Despite its importance, the transformation of snow into firn and then ice is still poorly understood and current predictive models have limited applicability. This project aims to develop a physically based firn-compaction model for the glaciological community. The team will take the first steps toward this goal through a set of field and laboratory experiments combined with model developments. The fieldwork will be at Taylor Dome in Antarctica. This project will introduce a new combination of firn datasets designed to lead to the development of next-generation, physics-based firn models. Advances in ice-core science and satellite altimetry demand firn models that can reliably simulate firn evolution in a range of climatic conditions, in a changing climate, and on long- and short-time scales. Current firn-compaction models are largely based on a steady-state assumption and tuned to particular geographical locations. Advancing beyond these models requires (1) measuring current firn-compaction rates (2) measuring grain-scale microstructures that play a crucial role in firn compaction, and (3) quantifying processes driving evolution of those microstructures. To decouple firn’s sensitivities to accumulation and temperature, the team will measure in situ strain rates by two independent methods and observe trends in microstructure in cores from sites spanning the accumulation gradient at Taylor Dome, while maintaining the same average temperature. The team will assess the ability of phase-sensitive radar to remotely measure firn-compaction rates, potentially simplifying future in situ measurements. This work will create a roadmap for collecting future microstructural data spanning key areas of temperature-accumulation space and simplify future collaborations through the availability of an open-source Community Firn Model.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.