SubZero: A Sea Ice Model with an Explicit Representation of the Floe Life Cycle

Abstract

Sea ice dynamics span a wide range of scales and exhibit granular behavior as individual floes and fracture networks become evident at length scales O(10--100) km and smaller. Existing floe-scale sea ice models use bonded elements of predefined simple shapes like disks or tetrahedra to represent more complex floe geometries. However, floe-scale modeling remains challenging due to its typically high computational cost and difficulties in reconciling the idealized nature of discrete elements with complex floe-scale observations. Here we present SubZero, a conceptually new sea ice model geared to explicitly simulate the lifecycles of individual floes by using complex discrete elements with time-evolving shapes. This unique model uses parameterizations of floe-scale processes, such as collisions, fractures, ridging, and welding, to bypass the high computational costs of resolving intra-floe bonded elements. We demonstrate the novel capabilities brought by the SubZero model in idealized experiments, including the summer-time sea ice flow through the Nares Strait and a winter-time equilibration of floe size and ice thickness distributions. The SubZero model could provide a valuable alternative to existing discrete element and continuous sea ice models for simulations of floe interactions.