Simulating in-plane failure of sea ice floes in the Arctic using discrete element methods

Sea ice is made up of individual pieces of ice called floes, and these floes can vary in size from scales of just metres to tens of kilometres. There has been much recent interest in simulating variable floe size in continuum models of sea ice, since floe size can impact the evolution of the sea ice cover via several mechanisms including lateral melt volume, rheology, and momentum exchange. These simulations usually only account for the breakup of floes driven by waves. Observations of the Arctic sea ice cover show that there also exists several mechanisms of in-plane floe failure resulting from processes including wind forcing, interactions between neighbouring floes, and thermal weakening. The limited availability of in-situ observations of these in-plane failure mechanisms inhibits the development of accurate parameterisations for use in continuum models. Discrete element models (DEMs) are able to resolve relevant properties such as shear and normal stress and sea ice strength at the sub-floe scale, and they can therefore directly simulate crack formation and propagation. DEMs can thus be applied as a virtual laboratory of floe breakup and be used to supplement observations to develop a more complete understanding of floe failure mechanisms.

In this study, we use well-characterised case studies of floe breakup events to test sea ice DEM capability in simulating the mechanical breakup of floes. We will present results from a series of DEM simulations to explore these observed case studies of floe breakup and identify important parameters and processes that impact whether the floe fails and the resulting floe sizes. We will also discuss the challenges that have emerged in applying a sea ice DEM to floe fragmentation at smaller scales.