Dynamic Observations of the Evolution of Firn

利用现代光谱学技术，PI将确定冰芯致密化和微观结构演变的机制作为深度的函数。一个80米长的硬岩心将在格陵兰的Summit钻取，然后运到达特茅斯。对于岩心的浅层部分，在那里，公司受到季节和日温度梯度的影响，PI将在岩心边界施加格陵兰原位温度梯度。连续ìCT将用于监测致密化和微观结构演变。对于地核的深处，在地核的长度上不存在格陵兰式的原位温度梯度。然而，它确实受到覆盖层重量的压力。因此，PI将在深核上进行格陵兰原位加载实验。连续ìCT将用于监测致密化和微观结构演变。ìCT实验完成后，将在配备冷级的扫描电子显微镜下对该公司进行切片和检查。电子后向散射和能量色散x射线光谱学将用于确定冰晶取向和局部微化学。小组认为，为学生提供的专业发展道路，包括参加未来教师教学系列和为期10周的“沟通科学”课程，构思得很好。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。冰盖融化的速度有多快仍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，研究人员将从格陵兰岛的顶峰站提取一个80米长的核心。在达特茅斯的一个寒冷的房间里，研究人员将对堆芯近表面部分的两端施加自然温度条件，并对堆芯较深的部分进行压缩测试。一套光谱学技术将用于监测核心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许多物理参数的值，这些参数将用于确定未来几十年的融化速率。

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.