Energy dissipation in viscous-plastic sea ice models
Most current sea ice models are based on the viscous approximation introduced by Hibler (1979). These viscous-plastic (VP) models approximate the small elastic deformations by the viscous deformations of a creeping flow. The resulting numerical treatment is much more simple than in earlier sea ice models, but viscous deformations introduce a non-physical energy sink in the model since they are not reversible as the elastic deformations. The project is aimed at assessing the consequences, physically speaking, of this non-physical energy dissipation in the models and therefore verifying the validity of the VP approximation. The dissipation is studied using the kinetic energy balance that is derived using the continuity and momentum equations for sea ice. This analysis allows us to evaluate the different terms of the balance and look at the relative importance of the viscous dissipation. The results will be presented for a 40km-resolution run of 1 year. The dependence of the viscous dissipation on the number of Newton loops of the numerical solver of the momentum equation is also studied. Preliminary results at 20km-resolution will also be shown.