Parallel Climate Model Simulations with a Dynamic-Thermodynamic Ice Thickness Distribution Model

Global climate model simulations exhibit an amplified polar response to anthropogenic climate change, mostly caused by ice-albedo feedback in the polar regions. The simulated ice-albedo feedback often depends on the choices of physical processes included (or parameterized) in each model. An improved sea ice component has been implemented in both the Parallel Climate Model (PCM) and the NCAR Community Climate System Model (CCSM), which are global, coupled atmosphere-ocean-sea ice models used for climate-change simulations. The new PCM/CCSM ice model includes: energy- and mass-conserving thermodynamics, a multiple-category ice thickness distribution model, and elastic-viscous-plastic ice dynamics. The thermodynamics includes four vertical temperature layers and temperature- and salinity-dependent thermal properties in the sea ice, with a fixed salinity profile.

Parallel Climate Model simulations of pre-industrial and present-day climate states with the new ice model will be presented and compared with PCM-1 simulations and sea-ice observations. A PCM simulation with five ice thickness categories will be compared to a 1-category simulation. The effect of the improved thermodynamics and thickness distribution will be discussed, as well as their potential impact on simulating ice-albedo feedback and the prediction of climate change.