Guest lecture by Assistant Prof. Takenobu Toyota, Hokkaido University, on Possible Formation Processes of Floe Size Distribution in the Seasonal Ice Zone
Seminars at NTNU AMOS in 2015
Guest lecture by Assistant Prof. Takenobu Toyota, Hokkaido University, on Possible Formation Processes of Floe Size Distribution in the Seasonal Ice Zone
Abstract:
In this seminar I will introduce my recent study on floe size distribution (FSD) in the seasonal ice zone (SIZ). SIZ is composed of various sizes of floes.
FSD is one of the basic parameters of sea ice, and plays essential roles in the dynamic and thermodynamic processes of sea ice extent. For example, in the melting season FSD determines the retreating rate of sea ice extent in SIZ because for a given ice concentration FSD controls the cumulative perimeter of floes that enhances melting.
From the dynamical aspect, it is considered to be related to the rheology of sea ice especially in the interior region. Therefore, it is important to clarify the general properties of FSD and understand how it is formed. This issue is closely related with the parameterization in the numerical sea ice model. Mathematically, it is shown from the field observations that FSD is basically scale invariant, irrespective of floe size, but it is also pointed out that the fractal dimension may have a different regime for smaller floes (< 20-40 m) and depends on the conditions.
I will introduce some results from field observations and talk about how we need to tackle this issue in the future.
About the presenter:
Dr. Takenobu Toyota, Assistant Professor
Institute of Low Temperature Science
Hokkaido University
E-mail: toyota@lowtem.hokudai.ac.jp
His original field of study was meteorology, when he was working for Japan Meteorological Agency for eight years after receiving a master of science degree at the University of Tokyo in 1987. In 1995 he started sea ice research at the Institute of Low Temperature Science, Hokkaido University, where he got a doctoral degree on the subject of properties of sea ice and surface heat flux in the Sea of Okhotsk in 1998. He is still continuing this research at the same institute as an assistant professor. His present interest is to understand the growth and melting process of sea ice in seasonal ice zone, which can be applied for the parameterization in a numerical sea ice model. For this purpose, he is now involved in the analysis of ice thickness, floe size, and physical properties of sea ice.