Thermodynamic feedback processes in a single-column sea-ice-ocean model

Due to large uncertainties in many of the parameters used to model sea ice, it is possible that models with significantly different physical processes can be tuned to obtain realistic present-day simulations. However, in studies of climate change, it is the response of the model to various perturbations that is important. This response can be significantly different in sea-ice models that include or exclude various physical feedback mechanisms. Because simplifications in sea-ice physics are necessary for general circulation model experiments, it is important to assess which physical processes are essential for the accurate determination of the sensitivity of the ice pack to climate perturbations. We have attempted to address these issues using a new coupled ice-thickness distribution-ocean mixed-layer model. The sensitivity of the model to surface heat-flux perturbations is examined and the importance of the ice-ocean and ice-albedo feedback mechanisms in determining this sensitivity is analyzed. We find that the ice-ocean and ice-albedo feedback processes are not mutually exclusive, and that they both significantly alter the model response to surface heat flux perturbations.