Dynamic Observations of the Evolution of Firn

利用现代光谱技术，等电点将确定冰芯致密化和微结构随深度变化的机制。将在格陵兰岛的顶峰钻取一个80米长的降雪岩芯，并将其运往达特茅斯。对于积雪受季节和昼夜温度梯度影响的核心浅部，PI将在核心边界施加格陵兰原地温度梯度。连续CT将被用来监测致密化和组织演变。对于核心的深部，在整个核心长度上不存在格陵兰原位温度梯度。然而，它确实经历了来自覆盖物重量的压力。因此，国际空间站将对深层岩心进行格陵兰式的就地加载实验。连续CT将被用来监测致密化和组织演变。在完成？CT实验后，将在配备冷台的扫描电子显微镜中进行切片和检查。电子背散射和能量色散X射线光谱分析将用于确定冰晶取向和局部微化学。专家小组认为，为学生的专业发展提供的途径，包括参加未来学院教学系列和为期10周的“传播学”课程，是经过精心设计的。由于北极异常变暖，格陵兰冰盖正在迅速融化。总而言之，冰盖储存的水足以使海平面上升6米。冰盖将以多快的速度融化仍然是一个悬而未决的问题。控制冰盖融化的一个重要因素是它的物理性质。在这项工作中，调查人员将从格陵兰顶峰站提取一个80米长的岩芯。在达特茅斯的一个冷藏室里工作，研究人员将在堆芯近表面部分的两端施加自然温度条件，并对堆芯更深的部分进行压缩测试。一套光谱技术将用于监测岩芯的三维实时致密化和晶体取向的演变。这些实验将提供模拟建模所需的众多物理参数的值，这些参数将用于确定未来几十年的熔化速度。

Using modern spectroscopy techniques, the PI will determine the mechanisms of ice core densification and microstructure evolution as a function of depth. An 80 meter firn core will be drilled at Summit, Greenland, and transported to Dartmouth. For the shallow part of the core, where the firn is subjected to seasonal and diurnal temperature gradients, the PI will impose Greenlandic in situ temperature gradients at the core boundaries. Continuous ìCT will be used to monitor densification and microstructure evolution. For the deep part of the core, where a Greenlandic in situ temperature gradient does not exist over the length of the core. However, it does experience stresses from the weight of the overburden. The PI will therefore conduct Greenlandic in situ loading experiments on the deep core. Continuous ìCT will be used to monitor densification and microstructure evolution. After the completion of the ìCT experiments, the firn will be sectioned and examined in a cold-stage-equipped scanning electron microscope. Electron backscattering and energy dispersive X-ray spectroscopy will be used to determine ice crystal orientations and local microchemistry.The panel thought that the path presented for the professional development of students, which include attending the Future Faculty Teaching series and the 10-week "Communicating Science" course, was well conceived. The Greenland ice sheet is rapidly melting due to extraordinary Arctic warming. All told, the ice sheet stores enough water to raise sea level by 6 meters. How fast the ice sheet will melt is still an open question. One important factor controlling the ice sheet melt is its physical properties. In this work, the investigators will extract an 80 meter core from the Summit Station, Greenland. Working in a cold room at Dartmouth the investigators will impose the natural temperature conditions on the two ends of the near surface part of the core and compression tests on the deeper part of the core. A suite of spectroscopy techniques will be used to monitor the 3-dimensional real-time densification of the core and the evolution of the crystal orientation. These experiments will provide the values of the numerous physical parameters required for simulation modeling, which will be used to determine the melt rates over the coming decades.