Anisotropic Continuum Model of Granulated Sea Ice

A continuum model describing sea ice as a layer of granulated thick ice intersected by long and narrow regions of thinner ice, leads, is developed. Sea ice is considered to be a two-dimensional granular material, whose deformation occurs through motion of floes generated in ice fracturing under applied stress. We consider dynamics of mesoscale leads generated under tensile stress, whose dimensions is larger than those of floes, so that deformation of the surrounding ice is described through the granular plastic rheology, but still sufficiently smaller than the basin scale, so that they can be modelled using continuum approach. The model consists of the stress expression depending on orientational distribution of lead characteristics, thick ice thickness and rheology. It also includes evolution equations for the orientational distribution of leads, their thickness and width expressed through second-rank tensors. The results of the calculations show that the model produces reasonable behaviour in simple flows. The consideration of the thick ice as granular material elliminates the problem of infinite lead opening under pure shear produced by an earlier model considering thick ice deformation only through ridging.