Consistent ridging and opening coefficients for multi-category sea ice models with modified viscous-plastic rheologies

Abstract. In multi-thickness category sea ice models, subgrid-scale ridging and the opening of leads are represented by a redistribution function. This function modifies the thickness distribution based on grid-scale strain rates. There is a physical link between sea ice rheology and redistribution by assuming that the work done by internal stresses in deforming sea ice is equal to the change in potential energy and frictional loss during the formation of ridges. Hence, modifications of the rheology require changes to the redistribution function to be consistent. For the special case of an elliptical yield curve and a non-normal flow rule, associated consistent ridging and opening coefficients can be formulated such that they reduce to the standard ones in the case of a normal flow rule. It is further demonstrated that the coefficients are independent of biaxial tensile strength. Satisfying specific criteria for the yield curve and plastic potential aspect ratios ensures that the ridging and opening coefficients are bounded by 0 and 1.