The Importance of Model Physics to Simulation of Arctic Sea Ice

Abstract:

Sea ice is a spatially and temporally varying thin layer whose existence and properties depend on small imbalances in fluxes of heat, moisture and momentum between the atmosphere and ocean; its accurate simulation in regional and climate models is a hard, and largely open, problem.

A large part of the uncertainty in simulation of sea ice can be traced to atmospheric and oceanic conditions and their variability. Here, however, we focus on the role of the fidelity of sea ice model physics to simulation of the sea ice state.

We briefly describe novel physics in a stand-alone, i.e. forced, sea ice model. These include the first physical model of melt ponds including the role of melt pond refreezing, anisotropic rheology, spatially and temporally variable form drag and its impact on sensible and latent heat fluxes, basal dissolution, a variable mixed layer, a diagnosed floe size, floe-size dependent lateral melt rate, and a physically-sophisticated frazil ice treatment. Model simulations, drawn from ongoing work, are used to illustrate the role of this physics on simulation of the sea ice state.

One of our chief conclusions is that accurate representation of the physics of sea ice processes, above and beyond what is the current state of the art in climate models, sensibly and significantly affects the ability of these models to make accurate simulations, and predictions, of the Arctic sea ice state.