Collaborative Research: Quantifying Heat/Mass Structure and Fluxes Through the Full Thickness of Greenland?s Percolation Zone

覆盖格陵兰冰盖的大部分雪在夏季的几个月里融化。这些融水在下面的雪中融化和重新冻结。随着时间的推移，这种改变的雪，也就是所谓的积雪，可以达到100米的深度。因此，积雪结构的这些变化改变了冰内以及冰盖与大气之间的热流。然而，到目前为止，由于观测仅限于浅层，因此不清楚积雪层的完整结构。为了解决这一重要的缺乏了解的问题，研究人员提出了一项实地研究，重点是钻探一些深冰芯，目的是表征深雪冰的热和物理特性。这些信息对于预测冰盖体积变化和海平面上升至关重要。该项目涉及研究生和本科生、一名早期职业科学家，并包括公众宣传活动，该项目将检验格陵兰低海拔地区的深层积雪因水渗透/再冻结和热强化压实而致密化的假设。该项目将开发一种新型的热水钻井系统，以快速穿透100米，通过技术上具有挑战性的混合冷和湿积雪条件。现场数据收集将包括数字温度串、视频和岩心测井以及仪器化钻杆。这项工作将产生一个全深度的特性，积雪厚度，密度，渗透性和热状态。此外，十年前在该地区进行的钻探将使调查人员能够评估积雪性质随时间的变化。最终，了解整个格陵兰岛的融水保留和重新冻结过程？的积累面积是必不可少的冰盖体积变化，流动动力学和海平面变化的提前预测。该项目将提供影响大量本科生和研究生的实地和实验室研究经验。该项目将支持一名新资助的年轻调查员，并将包括针对格陵兰和蒙大拿西部的公众和中学生的外联活动。

Much of the snow that covers the Greenland Ice Sheet experiences melting during summer months. This meltwater percolates and refreezes within the underlying snow. Over time, this altered snow, which is referred to as firn, can reach to depths of 100 meters. These changes in firn structure consequently alter the heat flow within the ice, and between the ice sheet and the atmosphere. As yet however, the full structure of the firn layer is unclear as observations have been limited to shallow depths. To address this important lack of understanding, the investigators propose a field study focused on drilling a number of deep ice cores, with the goal of characterizing the thermal and physical properties of the deep firn ice. This information is essential to predicting ice sheet changes in volume and sea level rise. The project involves graduate and undergraduate students, an early career scientist, and includes public outreach activities.The project will test the hypothesis that the deep firn in the low elevation regions of Greenland experience densification governed by water infiltration/refreezing and thermally enhanced compaction. The project will develop a novel hot water drilling system to quickly penetrate 100 meters through the technically challenging conditions of intermixed cold and wet firn. In situ data collection will include digital temperature strings, video and core logging, and an instrumented drill stem. This work will yield a full-depth characterization of firn thickness, density, permeability, and thermal status. Moreover, drilling conducted a decade earlier in the region will permit the investigators to assess changes in firn properties over time. Ultimately, understanding meltwater retention and refreezing processes across Greenland?s accumulation area is essential for advancing prediction of ice sheet volume change,flow dynamics, and sea level change. The project will provide field and laboratory research experiences impacting a large number of undergraduate and graduate students. The project will support a newly funded young investigator, and will include outreach activities targeting the general public and middle school students in Greenland and Western Montana.