The sea ice component of BCC_CSM1.1 is the GFDL Sea Ice Simulator (SIS). SIS is a global dynamical–thermodynamical sea-ice model, where the elastic-viscous-plastic technique (Hunke, 1997) is used to calculate ice internal stresses and the thermodynamics is represented by a modified Semtner scheme from Winton (2000). SIS has the same horizontal resolution as MOM4_L40 and three vertical layers, including one layer of snow cover and two layers of equally sized sea ice. In each model grid, five categories of sea ice are considered, according to the thickness of sea ice. It takes into account the mutual transformation from one category to another under thermodynamic and dynamical conditions. SIS calculates concentration, thickness, temperature, salinity and motions of sea ice and etc.