QuSI-DEM version 1.0: A polygon-based discrete element sea ice model in spherical coordinates. Part I: Model description

Abstract. Discrete element modeling (DEM) provides a methodology for simulating the dynamics of sea ice from fracture through post-failure granular behavior. Because the approach is designed explicitly to represent the cohesive or frictional forces between distinct floes, it may offer a better representation than continuum-based approaches for some phenomena. As such, discrete element models (DEMs) provide a complementary approach to sea ice modeling at geophysical scales. However, many uncertainties remain regarding best practices in the application of the method. These range from choosing element shape, element scale, contact physics, and numerical implementation. Here we describe a novel polygon-based discrete element sea ice model, developed with careful attention to the implementation details and the fundamental response of interacting element-pairs. The crack patterns that develop as a result of sea ice fracture depend critically on the elastic and dissipative response of the material. Propagation of cracks can depend as much on the characteristics of post-failure element contacts as intact ones. So, distinct parameters are introduced to the contact physics in this model to provide control of the failure rate and timing of transitions in contact response and to constrain the amount of energy and momentum transfer in the contact failure process. Stresses can be communicated over great distances in sea ice due to its rigidity. This can present difficulty in specifying boundary conditions for simulations of localized processes as remote influences may be large. With this in mind, other like other models in its class, this model is formulated in spherical coordinates, and borrows from finite element mesh generation and refinement techniques that make it possible to simulate across scales up to the planetary without excessinve computational cost.