Physical processes in polar ice sheets and high resolution analyses of Earth's history in climatic and environmental changes

点击翻译按钮获取中文摘要

The aim of the present study is to develop a new research field, Nanoglaciology, for better understanding the ice sheet processes on a macroscopic scale on the basis of various microphysical mechanisms involved in the processes, and to clarify the meaning of paleoclimate-and paleoenvironment-signals and their reliabilities. The main results obtained are summarized as ;1. A mass transfer in the firn and the formation process of layer structures : We revealed structural changes of the layering formed at the surface with depth by the use of various experimental methods. Using SEM-EDS and micro-RAMAN, we found that most of the trace ions are included in the micro particles of sulfate salts and other salts. We proposed a new reaction diagram for determining the product materials in relation to ion balances.2. Bubble to hydrate transition and gas fractionations : We found a new mechanism of hydrate nucleation that occurs on salt inclusions, and suggested that the layer structure in deeper part depends on a distribution of salt particles.3. Development of crystal fabrics and ice sheet flow: We developed a new model taking anisotropy of fabrics into consideration that has been neglected so far. Applying this new model to DML Antarctica, we found much larger flow velocity than that calculated by an isotropic flow model.4. Radar echo sounding of ice sheets : Using a new radar sounding system that was designed to detect internal structures of ice sheets, we found birefringence effect by the ice sheet for the first time. This new method enables us to deduce the internal fabric structures regarding to ice sheet flow.