Author(s): Susan Frankenstein; Mark A. Hopkins; Hayley H. Shen
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Abstract: From numerous field observations, it has become well known that pancake ice is ubiquitous in wave dominated polar seas. These strikingly uniform circular floes are consistently found in Antarctic seas during the ice formation season. Their presence has also been reported in the Bering Sea, the Greenland Sea, and in polynyas and leads within pack ice. Pancake ice forms through a combination of thermodynamic growth and mechanical thickening, caused by rafting of floes that is driven by wave motion. This complex growth process is much faster than pure thermodynamic growth and hence may be the main factor responsible for ice edge advance in marginal ice zones. We have developed a dynamic model of pancake ice that combines a three-dimensional discrete element model with wave hydrodynamics. We have used the model to calculate the dependence of open ocean ice drift speeds on wave amplitude. This drift velocity leads to the formation of an ice accumulation at the edge of the fast ice. We have simulated the accumulation of pancake ice floes at a non-reflecting barrier and studied the rate of thickening and the rate of increase of the impact force on the barrier. However, these studies neglected the effects of inertial forces exerted on the pancake ice floes due to fluid accelerations, wave reflection from the ice edge or barrier, and the feedback of the energy dissipation due to collisional dynamics and fluid drag into the wave hydrodynamics. We add these features to the computer model and repeat the previous studies of open ocean drift velocity.
Year: 2002