When CAM 3.0 is run uncoupled (i.e., without an ocean model), sea ice thickness and concentration must be specified. Sea ice concentrations are known with reasonable accuracy owing to satellite microwave instruments and ship observations. However, no adequate measurements of thickness exist to produce a comprehensive dataset. Therefore, when ice thickness must be specified, the thickness of the ice covered portion of the grid cell is fixed in space and time at 2 m in the Northern Hemisphere and 0.5 m in the Southern Hemisphere. Ice concentrations are interpolated from monthly input data, which may vary in space and time.6.1
For either coupled or uncoupled integrations, snow depth on sea ice is prognostic as snow accumulates when precipitation falls as snow, and it melts when allowed by the surface energy balance. For uncoupled simulations only, the maximum snow depth is fixed at 0.5 m. Rain has no effect on sea ice or snow on sea ice in the model.