EAGER: Constraining the Expected Brittle-ice Behavior for the Hercules Dome Ice-core Site.

冰芯是过去气候信息的重要来源。利用冰芯的研究得益于完好无损的冰芯记录。在冰原内部通常有一个区域，在那里，从冰芯中提取出来的冰是易碎的。当岩心从冰盖中取出时，其快速减压导致大面积破裂时，就会发生脆性冰行为。这个区域的冰可能会破坏完好的记录。该项目旨在提高我们对脆性冰行为和开始机制的理解，目的是帮助指导现场作业、岩心处理准备和计划的实验室测量技术，以用于未来的取冰项目，包括即将在Hercules Dome进行的工作。这个项目不需要实地工作，因为它将使用现有的观测和现有的冰芯来了解脆性冰。这是一个高风险和及时的建议，是早期概念和探索性的，使其适合于EAGER征求。该项目将支持一名早期职业研究人员，并为一名女性硕士研究生提供培训。最后，该项目将为研究生和本科生课程以及小学编制教育和外联材料。该项目将对几个现有冰芯样品中的脆性冰进行检查和分类，以具体评估影响脆性潜力的各种冰物理性质，包括气泡大小和数量密度、冰结构、晶粒统计、断裂特征、晶粒和亚晶粒边界的位置和性质。该样品评估的末端成员已经确定，包括表现出主要脆性行为和损伤的simple Dome，以及表现出非常轻微脆性行为且几乎没有损伤的South Pole冰芯。输出数据集将包括气泡数密度、平均颗粒和气泡大小、亚颗粒流行率和方向的校准关系，以及估计脆性冰开始和大小的可用指标。这项工作的结果可以立即应用于Hercules Dome钻井项目。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。

Ice cores are a vital source of information about past climate. Research that utilizes ice cores benefits from an undamaged ice-core record. There is often a zone within ice sheets where the ice is brittle upon extraction in a core. Brittle-ice behavior occurs when the rapid decompression of the core as it is being extracted from the ice-sheet results in extensive fracturing. Ice from this zone can compromise the undamaged record. This project seeks to improve our understanding of the mechanisms involved in brittle-ice behavior and onset, with the goal of helping to guide field-site operations, core handling preparation, and planned laboratory measurement techniques for future ice-coring projects, including the upcoming work at Hercules Dome. This project requires no field work, as it will use existing observations and existing ice cores to gain an understanding of brittle ice. This is a high-risk and timely proposal that is early-concept and exploratory in nature, making it appropriate for the EAGER solicitation. The project will support an early-career researcher and provide training for a master’s student who is a woman. And, finally, the project will develop educational and outreach materials for graduate and undergraduate courses and elementary schools.This project will examine and catalog brittle ice from several existing ice-core samples to specifically assess various ice physical properties affecting brittleness potential, including bubble size and number-density, ice fabric, grain statistics, fracture characteristics, and the location and properties of grain and subgrain boundaries. End members of this sample assessment have been identified and include Siple Dome, which exhibited major brittle behavior and damage, and South Pole ice core, which exhibited very-minor brittle behavior and almost no damage. Output datasets will include calibrated relationships for bubble number-density, mean grain and bubble sizes, subgrain prevalence and orientation, and a usable indicator for estimating brittle-ice onset and magnitude. There is an immediate applicability of results from this effort for the Hercules Dome drilling project.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.