MODELING SEA-ICE AS A GRANULAR MATERIAL, INCLUDING THE DILATANCY EFFECT

A dynamic sea ice model based on granular material rheology is present ed. The sea lee model is coupled to both a mixed layer ocean model and a one-layer thermodynamic atmospheric model, which allows for an ice albedo feedback. Land is represented by a 6-m thick layer with a const ant base temperature. A 10-year integration including both thermodynam ic and dynamic effects and incorporating prescribed climatological win d stress and ocean current data was performed in order for the model t o reach ii stable periodic seasonal cycle. The commonly observed lead complexes, along which sliding and opening of adjacent ice floes occur in the Arctic sea ice cover, are well reproduced in this simulation. In particular, shear lines extending from the western Canadian Archipe lago toward the central Arctic, often observed in winter satellite ima ges, are present. The ice edge is well positioned both in winter and s ummer using this thermodynamically coupled ocean-ice-atmosphere model. The results also yield a sea ice circulation and thickness distributi on over the Arctic, which are in good agreement with observations. The model also produces an increase in ice formation associated with the dilatation of the ice medium along sliding lines. In this model, incid ent energy absorbed by the ocean melts ice laterally and warms the mix ed layer, causing a smaller ice retreat in the summer. This cures a pr oblem common to many existing thermodynamic-dynamic sea ice models.