Short‐term ice motion modeling with application to the Beaufort Sea

Abstract

A short‐term, small‐scale ice motion model was developed in order to facilitate the comparison of various conceptual and numerical formulations. This ice motion model is comprised of two basic components: a momentum balance or equation of motion component and a thickness distribution component. The equation of motion component includes the standard terms relating to air stress, water stress, Coriolis force, sea surface tilt, and internal ice stress. In order to describe the internal ice stress, three different constitutive laws were implemented: a standard linear viscous constitutive law, a closed‐form viscous plastic constitutive law, and a piecewise linearized viscous plastic constitutive law. For the thickness distribution component, a choice of either a two‐level or a multicategory model may be used to characterize the spatial and temporal changes in the thickness distribution of the ice cover. The governing equations for both of these basic ice motion model components are presented. The finite element method based on the Galerkin method of weighted residuals is used to spatially integrate the resulting set of nonlinear partial differential equations while a standard recurrence relation is employed for the temporal integration. The selection of an Eulerian or Lagrangian description for both the equations of motion and the thickness distribution equations is also included in the model development. In order to investigate the response of the developed ice motion model and its various options, the model was applied to a 4‐day ice motion episode in the southern Beaufort Sea. The response of the ice motion model was quantified in terms of the magnitude and the spread of the difference between calculated and observed ice displacements. Comparison between the various model options is included and their effect on the overall model performance is discussed.