The Anisotropic, Elastic-Decohesive Constitutive Law in CICE: Implementation and Results

In today's sea ice models, the internal stress, mechanical properties and deformation of the ice pack are typically represented using an isotropic, viscous-plastic-type rheology. In this approach, the ice is in a continual state of plastic flow except when strain rates approach zero as the ice pack becomes rigid. In the latter case, a viscous 'creep' behavior is imposed to regularize singularities in the standard viscous-plastic approach; elastic waves regularize the singularities in the elastic-viscous-plastic variant of the model. In contrast, large-scale sea ice observations indicate that the ice moves as large, rigid plates with high shear values along long, narrow fractures between the plates. These fractures often represent open water areas within the ice pack, where ocean-atmosphere fluxes of heat and water predominate. To better represent the dynamics of these important features within the ice pack, we have implemented an anisotropic, fracture-mechanics based constitutive law, the elastic-decohesive rheology, into the Los Alamos Sea Ice Model, CICE. We compare results from this model with the original elastic-viscous-plastic rheology in CICE, with the original elastic-decohesive "MPM" sea ice model (solved with the Material Point Method using Lagrangian particles), and with observed data from the RADARSAT Geophysical Processor System.