Comparing stress and deformation characteristics of sea ice using continuum and discrete element models

Most continuum models of sea ice follow the principles laid down by the Arctic Ice Dynamics Joint Experiment (AIDJEX), a US-Canadian initiative from the 1970s (McLaren, 1981). AIDJEX developed a model in which sea-ice floes break like a deformable plastic material at spatial scales of tens to hundreds of kilometres. This approach treats sea ice as a continuum, with the ice cover varying smoothly in space and time. Discrete element models (DEMs) model sea-ice floes as bonded groups of individual elements, explicitly capturing interactions with surrounding floes. Bond failure represents out-of-plane processes, such as ridging, or the formation of open water, such as leads.

We consider the results from simulating the dynamic and deformation properties of sea ice from a DEM and a continuum model using the same set of highly idealised scenarios. The results illustrate how the DEM can be used to provide an ensemble of possible outcomes around the mean behaviour provided by the continuum model, with the ensemble spread being linked to the spatial resolution being considered. The impacts of different stress confinement ratios are considered, illustrating a link between the DEM fracture patterns and fracture patterns that are observed in laboratory experiments on sea ice as well as in field observations.

Although the patterns of deformation from the DEM look more comparable to observed sea ice fracture patterns, the conclusions from this study support the use of continuum models for pack ice dynamics, especially at larger spatial scales.