BC3. Basque centre for climate change – Klima aldaketa ikergai

Seminar / Mintegia / Seminario

Lecturer:
Prof. Nobuhiko Azuma
Nagaoka University of Technology (Japan)

Abstract:

The polar ice sheets that cover Greenland and Antarctica play a crucial role in the global climate system. Discharge of ice into the ocean by massive creep flow affects global sea level and the ocean/atmospheric circulation patterns that govern the climate of Earth. During the past two decades, several deep ice drilling projects have been conducted in Greenland and Antarctica, in order to investigate the physical and chemical properties of polar ice. From these investigations it transpires that molecular processes occurring within polycrystalline ice and at its grain boundaries play a decisive role in the dynamics of polar ice sheets, because they may determine the dominant deformation mechanisms of ice in situ. The fact that the creep of ice sheets occurs at extreme conditions (stresses lower than 100 kPa, temperatures down to −50ºC, strain rates about 10−12 s−1, and total shear strains exceeding 1000%) makes it very difficult to reproduce and clarify the mechanisms of polar ice deformation in laboratory. For these reasons, we decided to investigate the mechanics of ice sheets by understanding the microscopic behavior of water molecules within ice grains and at their boundaries. In this seminar I will talk about the physical properties of the grain boundaries of polar ice and their role in the dynamics of polar ice sheets. To this aim I present our recent experimental results of ultra-slow ice-creep tests by using a modified phase modulation homodyne interferometer and the results of creep tests with very fine polycrystalline ice obtained by a new method that exploits ice polymorphism.

Speaker’s Short Vita (By S.H. Faria, BC3):

Prof. Nobuhiko Azuma is Professor of Mechanical Engineering and Executive Director/Vice-President of the Nagaoka University of Technology, Nagaoka, Japan. He earned his Dr.Eng. degree in 1986 from the Department of Applied Physics, Hokkaido University, Sapporo, Japan, under the supervision of Prof. Akira Higashi. After that he worked as Research Assistant at the Department of Geological Sciences, State University of New York at Buffalo, USA, where he started his career as an ice core physicist in the group of Dr. Chester C. Langway, Jr., a pioneer of ice core research. Then, he returned to the Department of Applied Physics, Hokkaido University, Japan, to participate in the Japanese project of deep ice drilling at Dome Fuji, Antarctica. In the period 1988–1994 he visited Antarctica and Greenland several times performing tests and experiments for the deep drilling project and in 1994 he effectively started the deep drilling at Dome Fuji over the winter (deep drilling at Dome Fuji successfully finished in 2007, after retrieval of two deep ice cores amounting to more than 5 km of ice). In 1990 he was appointed Associate Professor of the Department of Mechanical Engineering, Nagaoka University of Technology, and became full professor in 2004. His research interests include ice core analyses, ice physics and ice drilling technology. He is regarded today as one of the leading names of polar ice physics worldwide.  

If you are interested in attending the Seminar, send an email to events@bc3research.org

30th April, DIPC offices (Paseo Manuel de Lardizabal, 4 SAN SEBASTIÁN) 

* The Seminar will be in English. / Mintegia ingelesez burutuko da. / El seminario se realizará en inglés.