C-axis fabric analysis of ice samples collected from the NEEM ice core@en

The focus of this Diploma thesis is the development of a new approach for the analysis of crystal orientations in polar ice, based on digital image processing. The c-axes orientations are measured on thin ice sections using automated polarized light microscopy. The measured data are stored in form of high-resolution digital images which have been evaluated only manually so far. The automatic detection of grains and grain boundaries and the extraction of their orientation and shape parameters enable a statistical acquisition of the ice microstructure. The analysis of c-axes distributions, grain sizes, misorientations between adjacent grains, grain boundary orientations etc. allows for conclusions about the active recrystallization mechanisms. This is of high importance for an improved understanding of ice de- formation and ice flow. The developed program is applied to analyze the microstructure in the NEEM ice core (Greenland).本学位论文（Diploma thesis）的研究重点为基于数字图像处理（digital image processing）技术，开发一种用于极地冰（polar ice）晶体取向（crystal orientations）分析的全新方法。研究采用自动化偏振光显微镜（automated polarized light microscopy），对冰薄片样品（thin ice sections）的c轴取向（c-axis orientations）进行测量。目前，测量所得的数据均以高分辨率数字图像的形式存储，且迄今为止仅能通过人工方式完成评估。通过自动检测晶粒（grains）与晶界（grain boundaries），并提取其取向与形状参数，可实现冰微观结构（ice microstructure）的统计分析。对c轴分布、晶粒尺寸、相邻晶粒间取向差（misorientations）、晶界取向等参数的分析，能够推断出当前活跃的再结晶机制（recrystallization mechanisms），这对于深化冰体变形与冰流运动的认知具有重要意义。本研究所开发的程序已被应用于格陵兰NEEM冰芯的微观结构分析。