Effect of sea ice rheology in numerical investigations of climate

Plastic sea ice rheologies that employ teardrop and parabolic lens yield curves and allow varying biaxial tensile stresses have been developed. These rheologies, together with the previously developed ellipse and Mohr-Coulomb-ellipse rheologies, are implemented in a thickness and enthalpy distribution sea ice model to examine the rheological effect in numerical investigations of arctic climate. The teardrop, lens, and ellipse rheologies obey a normal flow rule and result in a two-peak shear stress distribution. The first peak is at the zero shear stress; the second is near 16,000 N m(-1) for the ellipse and two lens rheologies and near 30,000 N m(-1) for the two teardrop rheologies. The location of the second peak depends on the fatness of the yield curve and the amount of biaxial tensile stress allowed. In contrast, the Mohr-Coulomb-ellipse rheology, based on Coulombic friction failure, does not tend to create the second peak. The incorporation of biaxial tensile stress tends to increase ice thickness in most of the Arctic. A fatter yield curve tends to increase the frequency of large shear stresses. An increased frequency of large shear stresses, in conjunction with the inclusion of biaxial tensile stress, tends to reduce ice speed and ice export, to enhance ice ridging in the Arctic interior, and to reduce ice ridging in the coastal areas, which has a significant impact on arctic spatial ice mass distribution and the total ice budget. The teardrop rheologies reduce spatial bias of modeled ice draft against submarine observations more than others. By changing ice motion, deformation, and thickness the choice of plastic rheology also considerably affects the simulated surface energy exchanges, particularly in the Arctic marginal seas.