Helge Drange and Mats Bentsen, Nansen Environmental Center
Dynamic and thermodynamic sea ice modules have been an integrated part of the global and regional Nansen Center versions of MICOM since 1996. The thermodynamic module incorporates freezing and melting of sea-ice and snow covered sea-ice, and is based on the thermodynamics of Semtner Jr. (1976); Parkinson and Washington (1979); and Fichefet and Gaspar (1988). The dynamic part of the sea-ice module follows the viscous-plastic rheology of Hibler III (1979), where sea-ice is considered as a two-dimensional continuum. The dynamic ice module has been further modified by Harder (1996) to include description of sea-ice roughness and the age of sea-ice.
The presentation is split into three parts: First, an overview of the structure of the sea ice system is given. Second, some results are presented based on an early version of the coupled MICOM-sea ice model, focusing on NCAR/NCEP-forced hindcast simulations for the northern high latitudes covering the period 1948 to present. Third, the treatment of the dynamic and thermodynamic sea ice in the new version of the Bergen Climate Model (ARPEGE AGCM + MICOM + sea ice) is given. The latter part includes a description of the coupling procedure, and the adjustment (or, in plain wording: tuning) of the strength of sea ice rheology, sea ice and snow albedo, and sea ice diffusion that were needed to obtain quasi-realistic extent and thickness distributions of the sea ice in both hemispheres.