Firn Metamorphism: Microstructure and Physical Properties

阿尔伯特/0944078该奖项支持一个项目，该项目旨在研究从雪到雪再到冰的转变，以及控制雪的过去大气样本存储能力的基本物理。资深研究人员、一名研究生和几名本科生将对南极洲几个地点的降雪岩芯的扩散率和渗透率剖面进行高分辨率测量，并将结果与使用先进材料表征技术(扫描电子显微镜和X射线计算机断层扫描)量化的微观结构相关联。使用来自不同地点的岩芯将使我们能够检查不同当地气候条件对降雪结构的影响。我们将使用这些结果来帮助解释在几个存在降雪空气测量的地点对降雪空气化学成分的现有测量。该项目有三个密切相关的目标：量化从表面到气孔关闭深度的降雪微观结构对降雪微观结构的依赖，确定气泡形成和包裹空气的深度，调查这些特征显示地点之间差异的程度，以及利用降雪空气成分和降雪结构的测量结果更好地量化大气组成(现在和过去)以及滞留在降雪和冰内气泡中的空气之间的差异，方法是将拟议工作的结果与在WAIS分水岭和大沙丘地点进行的降雪空气测量进行比较。该项目更广泛的影响是，这项研究将使我们能够阐明降雪微结构变质作用的基本控制及其对气体捕获过程的影响，这对于理解过去大气成分和气候变化的冰芯证据非常重要。该项目将为达特茅斯大学一名博士生的研究生研究奠定基础，为本科生参与冷藏室测量和推广提供大量机会。调查人员有成功指导女学生的记录，并将在此经验的基础上再接再厉。将与当地地球科学教师以及研究生和本科生一起设计一个关于极地地区在气候变化中的作用的教师培训模块。一旦开发和测试，该模块将提供给更广泛的极地研究社区，供其社区的教师使用。

Albert/0944078This award supports a project to investigate the transformations from snow to firn to ice and the underlying physics controlling firn's ability to store atmospheric samples from the past. Senior researchers, a graduate student, and several undergraduates will make high-resolution measurements of both the diffusivity and permeability profiles of firn cores from several sites in Antarctica and correlate the results with their microstructures quantified using advanced materials characterization techniques (scanning electron microscopy and x-ray computed tomography). The use of cores from different sites will enable us to examine the influence of different local climate conditions on the firn structure. We will use the results to help interpret existing measurements of firn air chemical composition at several sites where firn air measurements exist. There are three closely-linked goals of this project: to quantify the dependence of interstitial transport properties on firn microstructure from the surface down to the pore close-off depth, to determine at what depths bubbles form and entrap air, and investigate the extent to which these features exhibit site-to-site differences, and to use the measurements of firn air composition and firn structure to better quantify the differences between atmospheric composition (present and past), and the air trapped in both the firn and in air bubbles within ice by comparing the results of the proposed work with firn air measurements that have been made at the WAIS Divide and Megadunes sites. The broader impacts of this project are that the study will this study will enable us to elucidate the fundamental controls on the metamorphism of firn microstructure and its impact on processes of gas entrapment that are important to understanding ice core evidence of past atmospheric composition and climate change. The project will form the basis for the graduate research of a PhD student at Dartmouth, with numerous opportunities for undergraduate involvement in cold room measurements and outreach. The investigators have a track record of successfully mentoring women students, and will build on this experience. In conjunction with local earth science teachers, and graduate and undergraduate students will design a teacher-training module on the role of the Polar Regions in climate change. Once developed and tested, this module will be made available to the broader polar research community for their use with teachers in their communities.