The National Science Foundation's (NSF) Tokyo Office periodically receives and disseminates reports on research developments in Japan that are related to the Foundation's mission. NSF-sponsored researchers currently working in Japan prepare many of these reports. These reports provide information for use by the global science and engineering community.
Hayley Shen, Professor, Department of Civil and Environmental Engineering, Clarkson University, Potsdam, NY 13699-5710, prepared the following report. Prof. Shen visited Japan from Janurary 5 - April 4, 1999 as a Visiting Research Fellow (short-term) under the sponsorship of the Science and Technology Agency of Japan (STA). Dr. Takatoshi Takizawa of Japan Marine Science & Technology Center (JAMSTEC) and Prof. Motoyoshi Ikeda of the Hokkaido Univerity hosted her visit. Prof. Shen can be reached at: hhshen@clarkson.edu
Purpose:
Sea ice covers over 10% of the earth surface. Most sea ice is seasonal, melting and growing annually. The dynamic change of sea ice cover quickly responds and contributes to climate change. Seasonal ice cover is a biological breeding ground for much marine life. The growth and decay of the ice cover produce salt and fresh water, respectively. Differences in density of this water from the ambient causes vertical currents in the ocean, and, thus, contributes to deep-water circulation, which in turn drives global ocean circulation. Changes in sea ice cover not only directly affect marine production in the high latitudes, but also have long-term affects on ocean water circulation. Studies on sea ice formation and evolution are important to marine biology as well as global climate issues. The research conducted during this STA fellowship tenure included the following tasks:
These tasks were aimed at constructing better predictive tools for simulating sea ice growth and movement in the ocean, in response to climate change scenarios.
Current Models:
Sea ice formation is currently considered to result from thermodynamic processes only. However, dynamic processes due to wave rafting may be very important to ice cover thickening. The motion of ice cover driven by wind and current is resisted by internal stresses. Many theories have been proposed to describe the internal stresses, but their applicability to different types of ice cover has not been tested.
Objective:
The present research hopes to improve sea ice models by including more detailed physical processes. First, internal stress models need to be tested against data obtained from both remote sensing techniques and in-situ measurements. Second, ice formations under active hydrodynamic forcing, in addition to thermodynamic processes, need to be quantified.
Future Perspective:
Collaboration with Japanese researchers on sea ice will continue on all three tasks described in the "Purpose" section. Exchange of visits will be pursued. A joint field program will be discussed.
Collaborations established:
Sea ice modeling: Prof. Motoyoshi Ikeda, Division of Ocean and Atmosphere Sciences, Graduate School of Environmental Earth Science, Hokkaido University.
Data Assimilaton: Dr. Tsuyosi Wakamatsu, International Arctic Research Center.
Wave-ice Interaction: Dr. Takenobu Toyota and Prof. Kunio Shirasawa, Low Temperature Institute, Hokkaido University.