Dynamic Observations of the Densification of Greenland Firn under Compression using a microcomputed X-ray tomography, June 2017

The present dataset includes 2-Dimensional (2-D) micro computed tomography (CT) reconstructions obtained from depths of 10-80 meters (m) firn from Summit, Greenland using the micro CT in 2017; comparison before the strain with after the strain of 4% from reconstructed 3-Dimensional (3-D) images (horizontal cross section) from the micro CT for 30 m firn specimen; stress as a function of strain for depths of 10-80 m during interrupted compressive tests; plots of density, the area-equivalent circle diameter (ECDa – a measure of the feature pore-size), the structure thickness (S.Th - a measure of the feature grain-size), total porosity, closed porosity, the specific surface area (SSA) and the structure model index (SMI - a measure of the prevalent ice curvature) respectively as a function of strain for depths of 10-80 m; grain size obtained using the micro CT as a function of depth or strain; SMI evolution with depth for before the test for depths of 10-80 m; 2-D reconstructions obtained using the micro CT 0% strain to 4% strain for the 30 m specimen; semi-empirical model for the lattice diffusion and the grain boundary diffusion, and the mean relationship between the density and stress for all tests; comparison of the density calculated from micro CT data with density obtained from measurement of the mass-volume method at each depth; the fitted linear slope of each microstructural parameter with increasing strain for depths of 10-80 m; the fitted mean density and the fraction of lattice diffusion α evaluated using the semi-empirical model under the corresponding stresses. We share this dataset with other glaciologists, material scientists, experimental geophysicists, and all other researchers and engineers in order to improve our understanding on the scientific issue of snow, firn and ice.

本数据集包含2017年利用微计算机断层扫描（CT）获取的、来自格陵兰岛萨米特地区10-80米深度粒雪的二维（2-D）微CT重建图像；30米深度粒雪试样的微CT三维（3-D）重建图像（水平横截面）在4%应变前后的对比数据；10-80米深度粒雪在间断压缩试验中应力随应变变化的关系数据；10-80米深度粒雪的密度、面积等效圆直径（ECDa，孔隙尺寸的表征指标）、结构厚度（S.Th，晶粒尺寸的表征指标）、总孔隙率、封闭孔隙率、比表面积（SSA）及结构模型指数（SMI，主导冰曲率的表征指标）各自随应变变化的关系曲线；利用微CT测得的晶粒尺寸随深度或应变变化的关系数据；10-80米深度粒雪在试验前的结构模型指数（SMI）随深度变化的演化数据；30米试样从0%到4%应变过程中的微CT二维重建图像；晶格扩散与晶界扩散的半经验模型，以及所有试验中密度与应力的平均关系数据；各深度下由微CT数据计算得到的密度与通过质量体积法测得的密度对比数据；10-80米深度粒雪各微观结构参数随应变增加的拟合线性斜率；我们公开此数据集以供冰川学家、材料科学家、实验地球物理学家及其他所有研究人员和工程师使用，旨在增进对雪、粒雪及冰相关科学问题的理解。