A New Brittle Rheology and Numerical Framework for Large‐Scale Sea‐Ice Models

Abstract

Abstract We present a new brittle rheology and an accompanying numerical framework for large‐scale sea‐ice modeling. This rheology is based on a Bingham‐Maxwell constitutive model and the Maxwell‐Elasto‐Brittle (MEB) rheology, the latter of which has previously been used to model sea ice. The key strength of the MEB rheology is its ability to represent the scaling properties of simulated sea‐ice deformation in space and time. The new rheology we propose here, which we refer to as the brittle Bingham‐Maxwell rheology (BBM), represents a further evolution of the MEB rheology. It is developed to address two main shortcomings of the MEB rheology and numerical implementation we were unable to address previously: excessive thickening of the ice in model runs longer than about one winter and a relatively high computational cost. In the BBM rheology and numerical framework these shortcomings are addressed by demanding that the ice deforms under convergence in a purely elastic manner when internal stresses lie below a given compressive threshold. Numerical performance is improved by introducing an explicit scheme to solve the ice momentum equation. In this paper, we introduce the new rheology and numerical framework. Using an implementation of BBM in version two of the neXtSIM sea‐ice model (neXtSIMv2), we show that it gives reasonable long term evolution of the Arctic sea‐ice cover and very good deformation fields and statistics compared to satellite observations.