Author(s): Saki Kitadate; Shigeki Sakai

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Abstract: Frazil-ice crystals which appear in polar regions are affected by wave conditions and temperature, then develop into initial discoid pancake ice. Sometimes, this initial pancake ice may be called “silver dollar”. Initial pancakes grow in size with rafting, collisions and freezing between pancakes and form larger ones. So far the study about mechanisms of formation process from initial pancakes to larger ones and the maximum size of pancakes has been done. However, the formation process from frazils to initial pancakes, the conditions and the size have not been made clear yet. In this study we concentrate on the frazil-initial pancakes stage, and discuss the relation between the wave conditions and initial pancakes formation. We suppose that the movement of frazil particles on the water surface follows a fluid movement, and use the linear theory of the wave motion. When we calculate the wave field, we can see that waves compress the distance between frazil particles and acceleration acting on particles is the biggest at wave peak. We assume that surface tension is acting on particles further at wave peak, and try to describe the relation between the wave conditions and formation of initial pancakes from balance of the power by surface tension to draw to particles and the power by the acceleration to pull apart.

DOI:

Year: 2008