An initial numerical investigation of the extent of sea-ice ridging

A two-level, viscous-plastic, sea-ice model is modified to allow ridged and unridged ice to be treated separately. This is accomplished by introducing a third continuity equation with additional terms to transform level ice into ridged ice during deformation. The standard model is run for three years using observed forcing from 1981–83, along with three sensitivity runs, to investigate the role of strength parameterization and energetically consistent deformation on ridge production. As expected, most of the ridging occurs near the coast, with the highest ridged-ice fraction produced off the Canadian archipelago and northern Greenland coast. The sensitivity studies indicate that, although the ridged-ice fraction is very sensitive to the strength parameterization, the lead fraction and total ice volume are much less affected. Requiring the deformation to be energetically consistent with the assumed yield curve almost doubles the amount of ridged ice produced.