THE ARCHITECTURE OF AN ANISOTROPIC ELASTIC-PLASTIC SEA-ICE MECHANICS CONSTITUTIVE LAW

The architecture for a new large-scale anisotropic constitutive law in tended for use in a sea ice dynamics model is presented here. This arc hitecture accounts directly for refrozen lead systems in the pack ice strength (with an anisotropic failure surface) and in the ice thicknes s distribution (with an oriented thickness distribution). The lower li mit (5 km) of the model resolution is controlled by the fracture spaci ng of old, thicker ice and the maximum lead width. The upper limit of the model resolution (100 km) is controlled by curvature in the lead d irections and variations in the lead width. These, in turn, are contro lled by the variations in internal ice stress due to driving forces (w inds and currents), which set the time resolution. This architecture f eatures abrupt changes in the failure surface and the associated flow rule that cannot be averaged over a time step. In addition, the princi pal stress normal to a new lead must be zero as it opens. This model h as subscale simulations that allow for the inclusion of phenomena such as ridging, rafting, buckling, and fracture on the behavior of the ic e. With this new ice constitutive law, it is possible to test directly the ice failure strength, plastic flow rule, and ice thickness distri bution. The data most useful for this testing come from ice stress and position buoys together with synthetic aperture radar deformation dat a. Some data comparisons have already been made.