Collaborative Research: A Unique Opportunity for In-Situ Measurement of Seasonally-Varying Firn Densification at Summit, Greenland

这是一个由华盛顿大学和沙漠研究所的主要研究人员合作提出的建议。 他们将对积雪压实的时空变化进行详细测量，以促进对冰变形和不同领域的知识和理解，包括遥感，雪形态和古气候学。他们将使用钻孔光学地层学的概念，在格陵兰峰会的两个冬季和三个夏季进行详细的测量，该概念将使用钻孔相机记录墙壁的细节。这些细节可以随着时间的推移进行跟踪，以确定垂直运动和应变，这在浅层是由积雪压实。 对积雪压实的定量了解对于遥感质量平衡研究很重要，遥感质量平衡研究试图测量和解释冰盖高度的变化;表面可以由于积雪而上升，也可以由于冰流和增加的致密化速率而下降。对所有三个过程的定量知识是必不可少的。有证据表明，致密化的速度经历了一个季节性的循环，与温度的季节性循环有关。 在解释冰芯捕获的气体数据的古气候，重要的是要知道在什么时候气体实际上被困在冰。这些孔隙直到进入到积雪深处才会闭合，这导致了冰的年龄和被困气体的年龄之间的差异。如果夏季高温对压实的影响大于年平均温度，则气龄/冰期偏移可能计算错误。对积雪致密化物理学的进一步理解将有助于解释这些记录。加强冰川学、古气候学和遥感界的研究和教育基础设施：1）利用冰面测高法进行大规模质量平衡研究的研究人员将有一个新的积雪压实实际测量来源; 2）建模者将能够通过详细的压实测量来验证和改进现有的积雪压实模型; 3）新的热力学模型将使遥感研究能够根据积累和表面温度测量来估计随季节变化的积雪压实情况; 4）研究被困气泡气体以解释古气候的研究人员将获得关于积雪压实和气体封闭的物理学的新信息。整合研究和教育，以促进教学，培训和学习通过研究生，罗伯特L。霍利这项工作将有助于霍利博士论文的主题，谁将进行本项目的指导下，首席研究员。通过与罗尔夫Tremblay，中学科学和数学教师在吉格港，华盛顿，和拉尔斯龙，中学科学教师在齐佩瓦福尔斯，威斯康星州正在进行的合作，提高K-12教育。这个项目让我们有机会让中学生参与到科学奋进的整个生命周期中--从想法到假设，再到实验，形成结论和报告结果。鼓励通过一个项目网站广泛传播成果，为信息和非专业人员”，补充我们的同行评审期刊文章。

This is a collaborative proposal by Principal Investigators at the University of Washington and the Desert Research Institute. They will make detailed measurements of the temporal and spatial variations of firn compaction to advance knowledge and understanding of ice deformation and across different fields, including remote sensing, snow morphology, and paleoclimatology. They will make detailed measurements through two winter and three summer seasons at Summit Greenland using the concept of Borehole Optical Stratigraphy, which will use a borehole camera to record details of the wall. These details can be tracked over time to determine vertical motion and strain, which in the shallow depth is dominated by firn compaction. Quantitative understanding of firn compaction is important for remote-sensing mass-balance studies, which seek to measure and interpret the changing height of the ice sheet; the surface can rise due to snow accumulation, and fall due to ice flow and increased densification rates. Quantitative knowledge of all three processes is essential. Evidence suggests that the rate of densification undergoes a seasonal cycle, related to the seasonal cycle of temperature. When interpreting ice core trapped-gas data for paleoclimate, it is important to know at what point the gas was actually trapped in the ice. The pores do not close off until deep in the firn, leading to a difference between the age of the ice and the age of the trapped gas. If summer high temperatures have more impact on compaction than mean annual temperatures, the gas-age/ice-age offset might be incorrectly calculated. Greater understanding of firn densification physics will help the interpretation of these records. Broader Impacts- This project will: Enhance infrastructure for research and education in the glaciology, paleo-climatology, and remote-sensing community: 1) investigators working on large-scale mass-balance studies using ice-surface altimetry will have a new source of actual measurements of firn compaction; 2) modelers will be able to validate and improve existing models of firn compaction with detailed compaction measurements; 3) new thermo-mechanical models will allow remote-sensing studies to estimate seasonally-varying firn compaction based on accumulation and surface temperature measurements; and 4) investigators studying trapped bubble-gas for paleoclimate interpretation will have new information about the physics of firn densification and gas-occlusion. Integrate research and education to promote teaching, training, and learning through the support of a graduate student, Robert L. Hawley. This work will contribute to a PhD dissertation topic for Hawley, who will carry out this project under the direction of the Principal Investigator.Enhance K-12 education through ongoing collaboration with Rolf Tremblay, a middle school science and math teacher in Gig Harbor, Washington, and Lars Long, a middle school science teacher in Chippewa Falls, Wisconsin. This project gives us the opportunity to involve middle school students with the complete life cycle of a scientific endeavor- from idea to hypothesis, toexperimentation, formulating conclusions and reporting results. Encourage broad dissemination of results through a project website for the informedlayperson", supplementing our peer-reviewed journal articles.