The model consists of the coupled model blocks of the ocean, atmosphere and sea ice. The ocean model is based on the planetary geostrophic equations, with the addition of a linear drag term to the horizontal momentum equations. In the resulting frictional geostrophic system, density depends nonlinearly on the local values of temperature and salinity, which obey separate advection-diffusion equations and are also subject to convective adjustment. Energy-moisture balance model of the atmosphere is used. The prognostic variables are air temperature and specific humidity at the surface. The model solves a vertically integrated equation for air temperature by balancing incoming and outgoing radiation fluxes, sensible (turbulent) heat exchange with the underlying surface, latent heat release due to precipitation, and a simple one-layer parameterization of horizontal transport processes. The corresponding transport equation for humidity is forced only by precipitation and by evaporation and sublimation at the underlying surface. A simple representation of sea ice thermodynamics is used. Dynamical equations are solved for the fraction of the ocean surface covered by sea ice in any given region and the average height of sea ice. The model components are coupled by exchanges of the three basic quantities, momentum, heat and fresh water. Real continents and ocean depth distributions are applied.
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