An Overview of Microphysical Processes in Ice Sheets : Toward Nanoglaciology

• Main Author: Hondoh, Takeo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Institute of Low Temperature Science, Hokkaido University
• Subjects: Dislocation; stacking fault; plasticity of ice; clathrate hydrate; transition zone; eutectic depth; water-soluble microparticle; firn; gas fractionation; ice core; ice sheet; nanoglaciology; 400; Ice Sheet
• Online Access: http://hdl.handle.net/2115/45404

In recent years, substantial efforts among ice core researchers have been directed toward understanding microphysical processes occurring in ice sheets, because they could affect significantly the paleoclimatic and paleoatmospheric signals recorded in ice cores. For example, a very large fractionation of N2 and O2 found in the transition zone from air bubbles to air hydrates was successfully explained in terms of molecular diffusion in ice [1-4]. More recently, we found very many water-soluble microparticles, of which distributions and behavior must be a key to understand the chemical processes in ice sheets [5-9]. In the present poper behaviors of gas molecules and chemical species in ice sheets are summarized and discussed in the light of recent studies. Moreover, the anisotropic deformation of ice crystals is taken into consideration in recent research on ice sheet flow dynamics [10-13]. Although a very large anisotropy in plasticity of ice was well established in the 1960's by laboratory experiments, almost all ice sheet flow models developed so far have assumed isotropic ice because of difficulty in modeling the anisotropic deformation. As you will see in this volume, this difficulty can be surmounted by the new models [12,13]. In the present paper, I will discuss the fundamental dislocation processes in ice to better understand why and how ice deforms in different orientations. In order to emphasize the importance of integration of microphysical processes more closely with macroscopic phenomena, I will propose a new phase of glaciological research, designated as nanoglaciology, for further development of the ice core research. I. Microphysical properties, deformation, texture and grain growth