Purpose. The study evaluates the impact of incorporating a two-phase ice structure into a thermodynamic model on its mechanical and thermophysical properties.

Methods and Results. The vertical distribution of thermophysical and physical-mechanical properties of sea ice was investigated using a model that assumes thermodynamic equilibrium between freshwater ice and brine (in solid and liquid phases). The heat transfer process is described by a nonlinear one-dimensional heat diffusion equation, excluding the effects of penetrating radiation and brine migration within the ice thickness. Salinity distribution was modeled using two approaches: an empirical relationship between bulk ice salinity and thickness, and a polynomial function reproducing the C‑shaped vertical salinity profile typical of thin growing ice. Numerical experiments simulated the crystallization of brackish seawater under varying surface air temperatures, with and without accounting for the liquid phase in the ice cover. The results reveal the vertical distribution characteristics of thermophysical and physical-mechanical properties during ice growth.

Conclusions. The thermal conductivity of the upper ice layer is significantly lower when the two-phase structure is not considered, particularly during early ice formation. The permeability of ice formed from seawater with varying initial salinity and air temperatures was assessed. Time periods during which the upper ice layer of a specific thickness becomes impermeable to brine migration were determined.