LIM is a numerical model of sea ice designed for climate studies and operational oceanography. It is coupled to the ocean general circulation model OPA (Océan Parallélisé) and is part of NEMO (Nucleus for European Modeling of the Ocean). LIM is used in several global climate models contributing to the assessment reports of the IPCC (Intergovernmental Panel on Climate Change). The code is freely available under a software licensing agreement and can be downloaded from the NEMO website (www.nemo-ocean.eu/).
Two versions of the model are available:
- LIM2 is a three-layer (two of sea ice and one of snow) thermodynamic-dynamic sea-ice model. The effects of the sub-grid scale snow and ice thickness distributions are implicitly taken into account through an effective thermal conductivity. The storage of latent heat inside the ice resulting from the trapping of shortwave radiation by brine pockets is taken into account. The surface albedo depends on the state of the surface, the snow and ice thicknesses, and the cloudiness. Seawater can infiltrate the submerged snow when the snow−ice interface is depressed under the water level. Ice dynamics are simulated by assuming that sea ice behaves as a two-dimensional viscous-plastic or elastic-viscous-plastic continuum in dynamical interaction with atmosphere and ocean. For the transport equation, a numerical method that conserves the second-order moments of the spatial distribution of the advected quantity is used.
- LIM3 is the most recent version of LIM, which includes major new developments, e.g. multi-category thickness and multi-layer halo-thermodynamic module. Ice volume is redistributed among categories due to thermodynamic (growth and melt) and dynamic (opening, rafting and ridging) processes. The vertical sea ice salinity profile is parameterized as a function of this bulk salinity and the ice thickness. The model includes an explicit representation of brine entrapment and drainage, as well as the brine impact on sea ice growth and decay. The model also includes a snow-ice formation scheme. A parameterization of frazil ice production in open water areas is also incorporated. The age of each ice thickness category is explicitly modeled. Ice dynamics are simulated by assuming that sea ice behaves as a two-dimensional elastic-viscous-plastic continuum in dynamical interaction with atmosphere and ocean. Ice mechanical redistribution functions take into account both ridging and rafting processes as well as the influence of the ridge porosity.
- Fichefet, T. and M.A. Morales Maqueda, 1997. Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics. Journal of Geophysical Research, 102, 12609–12646, doi:10.1029/97JC00480
- Vancoppenolle, M., T. Fichefet, H. Goosse, S. Bouillon, G. Madec, and M.A. Morales Maqueda, 2009 : Simulating the mass balance and salinity of Arctic and Antarctic sea ice. 1. Model description and validation. Ocean Modelling, 27, 33-53, doi : 10.1016/j.oceamod.2008.10.005.
- Iovino, D., M. Vancoppenolle and T. Fichefet, 2013: Implementation of LIM sea ice model in the CMCC global ocean high-resolution configuration. Research Papers Issue RP02092013.