Maykut-Untersteiner model

The Maykut-Untersteiner model is a seasonally forced one-dimensional sea ice thermodynamics model with snow and saline ice layers. It couples radiative and turbulent surface fluxes, heat conduction, interior shortwave absorption, brine-dependent effective heat capacity and conductivity, snowfall, and a basal Stefan condition driven by prescribed ocean heat flux. Its annual sea-ice thermodynamic equilibrium is a periodic cycle with zero net yearly thickness change. The snow insulation and summer ice protection mechanisms compete, so additional snow need not reduce annual equilibrium thickness. The transient temperature profile need not be linear.

At fixed boundary temperatures, a snow cover decreases winter conductive heat loss through the resistance $h_s/k_s+h_i/k_i$ and inhibits sea ice growth. Its high albedo and persistence into summer reduce ablation. Therefore annual equilibrium thickness has competing snow sensitivities. The near cancellation at modest snow depth and thickening with persistent summer snow in the original Maykut-Untersteiner model are forcing-dependent responses, not a universal monotonically decreasing snow-thickness relation.

For annually repeated forcing, a thermodynamic equilibrium is a periodic temperature field and thickness cycle. The yearly integral of net ice growth is zero, although substantial winter growth and summer ablation can each occur. Equilibrium thickness must specify an annual mean or a phase of the cycle. A change in forcing can remove a perennial-ice solution without making every transient thickness decrease at the same rate.